Platinum-Palladium Photographic Printmakingjeffreydmathias.com/guide/PtPdPhotographicPrintmaking.pdf · ~~~~~ Guide to Platinum-Palladium Photographic Printmaking by Jeffrey D. Mathias

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Platinum-Palladium

Photographic Printmaking

A comprehensive guide to the process, techniques, materials, and methodsby

Jeffrey D. Mathias

Copyright April, 1993; 1996; 2002; 2005; republished 2020No part of this d ocum ent ma y be rep roduced in w hole o r in part w ithout the expre ssed w ritten perm ission of the A uthor.

~ CONTENTS ~

Chapter 1 - IntroductionBrief History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2

Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4

Workroom Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

Sink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

Ambient Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

Dehumidifying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7

Humidifying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7

An Outline for Learning the Pt/Pd Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8

Basic Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.10

Ready Equipment and Work Room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.10

Ready Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.10

Ready Stock Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11

Study Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11

Learn the Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.12

Learn to Make a Negative and Print . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.12

Photograph and Print . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.12

Further Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.12

Chapter 2 - CautionsSafety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1

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ACIDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1

SOLVENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1

OXIDIZERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2

POISONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2

ULTRA-VIOLET LAMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3

OTHER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3

Hazard Ratings and Storage Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5

Chapter 3 - Negative ControlSensitometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1

Simultaneous Exposure and Development Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

Making a Rough Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

Evaluating the Rough Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7

Fine Tuning the Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8

Evaluating the Fine Tuned Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9

Normalization with The Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11

Evaluation with The Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12

Chapter 4 - EquipmentNotebooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1

Safe Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4

Positioning the Lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4

Measuring Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5

Solid Measure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5

Liquid Measure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5

Droppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

Calibrating Droppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

Storage Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

Coating Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

Developers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

Clearing Baths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

Contact Printing Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8

Light Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9

Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9

UV Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9

Sun vs UV Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.11

Processing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12

Chapter 5 - Raw MaterialsChemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1

Coating Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1

Sensitizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1

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Sensitizer Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2

Metal Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2

Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3

Contrast Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3

Processing Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4

Developers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4

Clearing Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5

Other Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6

Preparing Ferric Oxalate Powder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.7

Substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8

PAPER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8

FABRIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.9

Paper Info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.11

Descriptions of papers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.12

Chapter 6 - ChemistryFormulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1

Process Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3

Process Equations for Ferric Oxalate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3

Process Equations for Ammonium Ferric Oxalate . . . . . . . . . . . . . . . . . . . . . . 6.4

Formulas for Ferric Oxalate Sensitizer Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5

FO Sensitizer Formula Calculator (requires a JavaScript capable browser)

Optimized Formulas for Metal Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7

Metal Solution Formula Calculator (requires a JavaScript capable browser)

Quick Formula Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9

Making a Percent Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.10

Weighing Out Dry Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.12

Preparing the Stock Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.14

Sensitizer Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.14

Contrast Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.14

Metal Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.15

Developers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.15

Clearing Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.15

Modifying an Existing Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.19

To make a solution STRONGER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.19

To make a solution WEAKER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.20

Chapter 7 - CoatingThe Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1

Coating Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2

Preparation Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2

Brushing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2

Drying Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3

General Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3

Preparing the Coating Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5

Coating Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5

http://jeffreydmathias.com/guide/formulae_calculator_FO.htm

http://jeffreydmathias.com/guide/formulae_calculator.htm

http://jeffreydmathias.com/guide/chapter6.pdf

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Sensitizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5

Metal Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6

Pt/Pd RATIOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6

Double Salts of Palladium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6

Contrast Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7

Potassium Chlorate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7

Hydrogen Peroxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7

Potassium Dichromate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7

Ammonium Dichromate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7

Na2PtCl6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7

Mixing the Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8

Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8

General Expectations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9

Keeping Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9

Coating Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11

Explanation of Coating Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11

Measurement of Coating Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11

Calculation of Coating Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.12

Coating Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.13

Definition of Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.13

Coverage Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.14

Some Coverage Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.14

Coating Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.17

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.17

Humidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.17

Brushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.18

Drying the Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.19

Drying steps for DOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.20

Drying steps for POP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.20

Coating Fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.22

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.22

Brushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.22

Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.23

Drying steps for DOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.23

Drying steps for POP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.24

Drying the Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.25

Quasi Multi-Coating Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.26

Chapter 8 - ExposureLoading The Contact Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1

Exposing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3

Exposure by Direct Sunlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3

Exposure by Sunlight, but in Shade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4

Exposure by an Artificial UV Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4

Printout Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5

DOP Printout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5

-v-

POP Printout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5

Chapter 9 - ProcessingDeveloping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1

Notes & Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1

Disposal of Acid Developers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2

Clearing Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3

Clearing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4

Disposal of Acid Clearing Baths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5

Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6

Chapter 10 - Optional ProcessingBrightening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1

Chapter 11 - FinishingSpotting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1

Etching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2

Whiteout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2

Matting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3

Chapter 12 - Building Analog NegativesGeneral Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1

Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4

Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5

BASE FILM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5

MASK FILM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5

Processing Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6

Building the Positive and Shadow Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7

MAKING THE POSITIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.8

MAKING THE SHADOW MASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.8

Building the Negative and Highlight Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.9

MAKING THE NEGATIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.9

MAKING THE HIGHLIGHT MASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.10

Manipulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.11

Chapter 13 - Building Digital NegativesBuilding Digital Negatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1

Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1

Ink Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1

Registration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2

Posterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2

Calibration: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2

-vi-

Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3

Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.3

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4

Stack Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5

Multiple or Tri-Negative Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5

Comparison of Methods for producing Digital Negatives . . . . . . . . . . 13.5

Stack Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.7

PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.7

Software Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.10

Normalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.11

Color Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.12

Standard Curve Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.13

Optional Creative Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.14

Pt/Pd Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.15

CALIBRATION PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.16

Color Mix Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.17

Maximum Black Calibration (1st of 2 parts) . . . . . . . . . . . . . . . . . . . 13.19

Maximum White Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.20

Maximum Black Calibration (2nd of 2 parts) . . . . . . . . . . . . . . . . . . 13.22

Base Curve Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.23

Appendices to Building Digital Negatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.31

Building Density Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.31

Building a Gradient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.32

Optimizing the Original Negative for Scanner Noise . . . . . . . . . . . . . . . . . . 13.33

Puddling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.37

Registration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.38

Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.40

Sharpening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.42

Chapter 14 - TestingTesting the Ferric Oxalate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1

Fogging Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.4

Test for Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5

Chapter 15 - StudiesEmpirical Verification of the POP Process Equation

and Optimization of the Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1

PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1

SUBSTRATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1

COATING CHEMISTRY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1

AMBIENT CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2

EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2

PROCESSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2

OBSERVATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3

EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3

AFO40 SERIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3

-vii-

AFO40 vs AFO60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3

FO SERIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3

FO vs AFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3

FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4

THE POP EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4

CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4

Verification of Metal Solution Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.6

The Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.6

Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7

General Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7

Overall Substance and Presence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7

Image Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7

Image Graininess of large tonal areas . . . . . . . . . . . . . . . . . . . . . . . . . 15.7

Paper Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.8

Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.8

Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.8

Quasi Multi-Coating Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.9

Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.9

COVERAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.9

THRESHOLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.10

QUASI MULTI-COATING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.10

Further Data and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.10

Conclusions and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.11

An advantage of the double Quasi Multi-Coating . . . . . . . . . . . . . . . 15.11

Additional Pondering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.12

Wet Dry Drying Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.14

Ambient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.14

Materials and Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.15

Weighing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.15

Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.15

Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.16

SOLARIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.16

PRINTOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.17

PRINT COMPARISONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.17

WEIGHT COMPARISONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.17

CHEMISTRY CONSUMPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.17

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.18

Threshold for FO solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.19

The Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.19

Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.20

Conclusions and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.21

Relative Comparison of FO Powders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.22

Verification of FO Powder Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.30

Expected Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.30

Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.31

Measurement of Specific Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.32

-viii-

Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.32Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.32Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.27

Measurement and Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.33Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.34

Chapter 16 - More StudiesStudy of Oxalic Acid Concentration in the FO Sensitizer . . . . . . . . . . . . . . . . . . . . . 16.1

Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2

Study of the Clearing of Pt/Pd Prints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.4

CRITICAL CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.4

MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.5

PROCESSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.7

IDENTIFICATION & NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . 16.7

OBSERVATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.8

CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.10RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.10

A Look at Grain in the Film and Details in the Print . . . . . . . . . . . . . . . . . . . . . . . . . 16.12

Chapter 17 - AppendicesPreparation of Ferric Oxalate Powder

Relative Comparison of FO Powders Using Prints ........................................ . . . . . 15.39

http://jeffreydmathias.com/guide/FO_intro.html

~~~~~~~~ Guide to Platinum-Palladium Photographic Printmaking by Jeffrey D. Mathias ~~~~~~~~

1.1

Chapter 1 - IntroductionBrief History

The platinum process descended from other iron based processes such as Cyanotype in the mid1860's. Known as Platinotype, it was patented by William Willis, of Great Britain, in 1873. ThePlatinotype gained much popularity being both beautiful and the most archival of any printingprocess. With the increasing cost of platinum and the mass production of fine gelatin silver papersin the mid 1930's, Platinotype fell by the wayside. Although, several photographers continued tomake fine platinum prints.

In the early 1970's two things happened. Commercial gelatin silver paper was lessening in quality.And, George Tice wrote an article on hand coated platinum prints in Caring for Photographs, avolume of the Life Library of Photography published by Time Life Books in 1972. This rekindledthe interest in hand coated platinum prints. Several contemporary photographers prefer to utilizethis process because they find the platinum print to be a most beautiful object. Many find that thePlatinotype process more closely represents the way they wish to see the image.

For some fascinating information on the history of the platinotype, read The Eighth Metal: the Riseof the Platinotype Process by Mike Ware located on his web site. Early references to thePlatinotype Process can be found in the various editions of the Silver Sunbeam.


1.2

Description

The platinum-palladium (Pt/Pd) process is an iron based process. Other, different iron basedprocesses include Cyanotype and Kallitype. The light sensitive component of theplatinum-palladium process is Ferric Oxalate. Upon exposure to light the Ferric Oxalate istransformed into Ferrous Oxalate. The basic difference is that Ferric has a covalence of +3 andFerrous has a covalence of +2. These are differences in the associated electrons which cause themolecule to bond differently. A property of the Ferrous Oxalate is to reduce Noble metals from theirdouble salts and revert back to Ferric Oxalate. This reaction is known as Brewster's Reaction.Platinum and Palladium are Noble metals. The resulting print consists of these pure Noble metalsimbedded in the fibers of a substrate.

The Ferric Oxalate sensitizer provides for what is termed a Develop Out Process (DOP). The imageprints out partially and must be enhanced by use of a developer (although this not actually adeveloper or a development, but rather an enhancement.) Another sensitizer, Ammonium FerricOxalate, provides in certain occurrences for what is called a true Printing Out Process (POP). Theimage prints out fully with exposure. No development or enhancement is necessary. Both of thesesensitizers are used to make Pt/Pd prints and provide for differing results in the prints.

The sensitizer is most sensitive to the Ultra Violet (UV) and blue portion of the light spectrum.However, it must be remembered that the Ferric Oxalate will also react to heat and time. It is a goodtechnique to expose within an hour of coating DOP and immediately upon coating and drying POP.An unexposed coating is susceptible to change and deterioration even if hermetically sealed andfrozen.

The platinum and palladium salts may be used interchangeably or in combination, with eachscenario producing unique qualities in the photographic print. The metals can be mixed into anaqueous solution useful for this process when they are in the form of a double salt. The double satis basically the Nobel metal chloride (such as PdCl2) combined with a chloride salt (such as NaCl). The platinum double salt is typically that using Potassium, K2PtCl4. However the ammonium salt[(NH4)2PtCl4] is sometimes used. The palladium double salt can be any of the period I chloride saltsor ammonium. It is important that the salt and double salt be soluble in water.

Note: At this point, the author is currently using K2PtCl4, Li2PdCl4, Na2PdCl4, and K2PdCl4.

It is important that a sufficient amount of metal be deposited into the substrate that will provideoptimum image quality. An amount of metal beyond that will only be wasted, while not enoughmetal will result in a weaker print. Each metal salt has an optimum solution for a particularsensitizer. The simplified chemical equations for the Pt/Pd process are presented in the section"Process Equations" in Chapter 6, Chemistry. Optimized formulas for the metallic salts are foundin the next section of Chapter 6.


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Contrast can be altered with several contrast agents, materials and techniques. It is highly suggestedthat near to correct contrast (if erring, on the low side) be given to the negative.

Everything other than pure metallic platinum and/or palladium is cleared from the print with aclearing solution. The final result is the platinum and/or palladium metals embedded in the fibersof the substrate.

Please note that all of the methods, procedures, techniques, items, and things within this guide havebeen tried and tested by the author. Those that work are currently in use by the author, and thosethat don't are so stated. Every paper, chemical, or process variation can produce a unique nuancein the print and an incredible amount of diversity and control. After gaining proficiency in thisprocess, it is important that various new materials be tried.

Technique is the key to control. Technique is presented fairly well in this Guide, but it is somethingthat has to be mastered. Only with much practice will experience develop. Experience will thenprovide insight into the materials, process, and technique. Experience becomes the key toconnecting the print to the eye.

There are certainly many untried and undiscovered nuances of the Pt/Pd process. Additions ormodifications may be made to this guide at any time. Any questions or comments can be served viaE-mail.


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Tips

Some general recommendations follow.

� It is recommended that this process be learned using 4x5 negatives. In this way it shouldcost less to master the process, and the prints should still be of a large enough size toevaluate. The 4x5 size negative is also the easiest to individually process.

� Go easy with filters on the camera. This process can discriminate extremely subtledifferences in tonality. What may call for a #8 filter in silver printing may only require a #3filter in this process. (Note: If heavily filtered dark skies are what's wanted, print them ingelatin silver. The results will be much better. One should always take advantage of theparticular nuances any process or material has to offer.)

� The negative should be made in agreement with the process as well as the subject. Theplatinum palladium process utilizes more of the negative's information demanding a morecarefully controlled negative. It is a advisable that one complete the Matrix described in theNegative Control section. With this process there is little room for exposure or developmenterror if the highest quality and full advantage of the unique attributes are expected.

� The amount of UV light required to print a platinum-palladium photograph dictates that themost efficient method of exposure be contact printing. An enlarger lamp would likely causedamage to the negative before enough light could expose the print or take an extremely longtime. Enlarged prints can be made however, by building larger negatives. In order to getthe proper densities in these negatives (which also require masking), a good understandingof the platinum-palladium process is required. It is recommended that one first masternegative control and printing before attempting negative building.

� The sooner one moves away from using kits, the better. Better still, DON'T USE KITS. Kitsor pre coated material deprives one of some of the essential elements and understanding ofplatinum-palladium printmaking.

� Some kit materials can be put into use or modified so as to not go to waste. See the sectionModifying an Existing Solution in Chapter 6.

� The intent of this guide is that when starting out, one could do exactly and only exactly asin this guide and learn to make quality Pt/Pd prints. It is recommended to not changeanything until that which is specified is mastered. A check to see if one is ready to modifyor deviate is that they have mastered enough to throw away this Guide and write their own.

� Always remember, if one does not get CONSISTENT results, then THEY must be doingsomething incorrect. With the proper control, this process is very consistent.


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LightingElectricalPlumbingSinkVentilationAmbient Control Heating Cooling Dehumidifying Humidifying

Workroom Considerations

The Platinum Palladium process should be performed in a work spacecapable of providing for safety, control, and consistency. It is suggestedto first lay out and draw the entire work space on paper carefullyconsidering all components and the flow of the work. If more than oneperson is to be in the workroom, ample space should be provided for anuninterrupted work flow. It is most convenient to be able to construct theentire workspace, including walls, but in many situations the work spacemust be designed to fit within an existing space. The designcharacteristics should include those of a standard film processing area andinclude the following.

Lighting - The area must be light tight but have ample light for working. All areas should haveswitchable bright white illumination and appropriate safelights for film used andPt/Pd materials. Although not as sensitive as film, Pt/Pd coatings can be fogged bystray light. See the section on Safe light for the appropriate lamp to use for Pd/Pt.The Pt/Pd safelight(s) should fully illuminate all work areas.

Electrical - All outlets should be GFI (Ground Fault Interrupt) protected. Each work surface orarea should have at least four outlets, including the sink area. Outlets should beplaced above the work surfaces such as with kitchen counters. Outlets at a sinkshould be high enough to avoid being splashed upon. Two or three 20 Amp circuitsshould be used for the outlets. An additional two or three 20 Amp circuits should beused for ambient controls and ventilation. One 15 Amp circuit should be used forlighting. All electrical should adhere to all codes.

Plumbing - It is recommended that water be filtered to 0.5 microns. It is convenient to have bothhot and cold water and a mixing valve. The entire drain and source lines near thesink should be plastic (PVC, CPVC). It is suggested to have several valves along thesink to which tubing can be attached. Any metal in the vicinity of the sink will likelycorrode (including valves). A large plastic bucket is a must for proper dilution anddisposal of spent developer, clearing baths, and other solutions suitable for draindisposal after neutralization and dilution. Solvents should not be needed, but if everused should be recycled and NEVER disposed of down the drain. All acids andother suitable solutions are neutralized in the bucket, diluted, then disposed of downthe drain. Drain pipes should be plastic and not iron. All plumbing should adhereto all codes.


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Sink - Two sinks would be ideal as Pt/Pd and film processes do not agree. 3 x 10 feet minimumshould be the sink size considered for up to 16x20 inch prints. If only one sink is used, itshould be thoroughly washed when changing from film to Pt/Pd. The sink can be made ofwood with an epoxy paint. Plastic grids, as those used with fluorescent lamp housings, canbe placed on wood bars above the sink bottom to keep the trays elevated. Stainless steel andother metals should not be used and will have Pt and Pd transfer to it and may be etched bythe acids and solutions used.

Ventilation - Air must enter the room as well as leave the room. The best exit location is along theentire back of the sink. In this way, fumes from processing, as processing is done inthe sink, will be removed by the shortest path. The input location should be thefarthest from the sink and on the other side of coating and exposure areas. Any dustfrom coating and ozone from lamps should readily enter the path of the air flow.This will direct the design and layout of the room. A heat exchanger built into theventilation system can dramatically save on heating and cooling costs. Any airentering the room should be filtered. The air path in a properly designed systemshould enter through a filter; pass through a heat exchanger; be ducted to the farthestpoint from the sink; be cooled, heated, humidified, or dehumidified; pass through thecoating area; pass through the exposure area; pass over the sink; enter ducting alongthe back of the sink; pass through the heat exchanger; be ducted to the outside awayfrom the intake. The appropriate ducts should be insulated. It is useful to havevariable speed control as the airflow can be slower when it is not necessary toevacuate a lot of fumes. This will help with control of the ambient conditions. When needed, the ventilation flow can be increased. The maximum airflow shouldbe that necessary to keep the air quality at a safe and comfortable condition. A gooddesign of laminar flow across the sink area should allow for lower air flows.

Ambient Control - Ambient control is a serious consideration with the Pt/Pd process. There arecertain conditions which have dramatic affects on the print. Consistency andcontrol can be regulated with the ambient conditions.

Heating - Heating is primarily for the comfort of the individual. A small ceramic space heatercan easily supplement what is lost by the heat exchanger. The temperature shouldbe typically less than 70oF.

Cooling - High temperatures can play havoc with this process. When using the AmmoniumFerric Oxalate sensitizer (POP), it is recommended to keep the ambient temperaturebelow 70oF. As the temperature increases above 70oF, grain in the print increases.At above 90oF, this graininess is so profound that the image blurs and becomessplotchy degrading more at higher temperature. The ambient temperature should bekept below 70oF with Ferric Oxalate (DOP) as well. A air conditioner should belocated as per the ventilation design. An air conditioner is also important as the


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dehumidifier can produce a good amount of heat while running.

Dehumidifying - DOP works better at lower relative humidity (RH), the lower the better. Onecannot get the paper "bone dry" at high levels (>50%) of RH. This mostlikely results in a lack of maximum density. For DOP it is suggested to keepthe RH below 40%. With POP, the highest recommended RH is 70%. Athigher RH the probability of producing a quality print diminishes quickly.In some climates, if one dehumidifier doesn't do the job, try two. Rememberthat the outside humidity is coming in with the ventilation.

Humidifying - With POP, the higher the RH, the cooler the color of the image. The best way tohumidify is with a sonic mister. This can be the same mister used for humidifyingthe paper prior to coating. A more constant ambient RH may be achieved by runningthe dehumidifier and mister at the same time.


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An Outline for Learning the Pt/Pd Process

The intent of this section is to provide orderly guidance for learning the Pt/Pd process. Asprerequisite, it is assumed that the novice has experience and a full understanding of operating acamera, processing film, the Zone System, and general photography. The Pt/Pd process requiressome basic skills in chemistry and photography and utilizes some expensive materials. There aremany less time consuming and less expensive photographic processes one can pursue. One shouldnot consider the Pt/Pd process without having the dedication and commitment it demands. If onewishes to try their hand at this process, it is recommended that they attend a workshop or obtainpersonal instruction from an experienced Pt/Pd printer. Only after a firm commitment is decidedon should they purchase all the materials necessary. It is recommended that one NOT work fromkits, pre-coated material, or other shortcuts as this will not provide the level of quality results northe necessary experience.

The follow steps roughly outline a recommended sequence referenced to the various sectionsthroughout this guide. It should be expected that one technique or activity may be dependent onothers. One should not become surprised if after learning a particular technique, they find that theymust modify it after learning something else. The information in this guide has been assembled overyears and decades. As new discoveries are made, sometimes old procedures or techniques must bemodified. A key to developing good technique and procedure is achieving consistency of results.Much of the effort into what may seem tedious study or careful control circumvents the manypotential pitfalls and problems one is likely to encounter.

Throughout this guide a distinction has been made of several terms.

Process - is the set of procedures which utilizes certain materials under certain conditions andemploys certain techniques to produce a certain result (such as the Pt/Pd process).One selects the process, but does not alter the process. Once a process is fullyunderstood, one may develop sub-processes or variations of the process (such asDOP [Develop Out Process] and POP [Print Out Process]).

Procedure - relates to the steps or group of steps of a process. Procedure may be influenced byvariations in conditions or technique, but procedure is independent of personaltechnique. One generally sticks with a procedure that works and only modifies itwhen study shows a necessity. Technique is modified to accommodate procedure.

Technique - relates to events dependent on the individual and their personal skills. One'stechnique may differ from another, but the final result should be the same. Forexample when weighing, the same weight should be concluded from whateverpersonal technique and equipment is used. One must determine and master their owntechniques. Techniques may be borrowed and practiced, but are typically modifiedto personal desire. It is important that one carefully develop their techniques so as


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to be conducive with the greatest success. Consistency and accuracy are importantqualities of technique.

Method - relates to a sub-procedure or set of procedure which can lead to similar process orsub-process results (examples are: single or multiple coating methods; digital oranalog negative methods). One can choose from several known methods or developtheir own. However like procedure, the development of methods requires a goodunderstanding of the process.

Conditions - are those such as temperature, relative humidity, pressure, environment and such andcan be placed into two categories.

Boundary conditions are limitations that the process should or must operate within.For example: a safe light must be used to prevent exposure of sensitized material tothe threshold of illumination that can convert the sensitizer.

Ambient conditions are those present which may cause variation of the results andshould be monitored and controlled if necessary. For example: the relative humiditymay be varied within a range (of boundary conditions) to influence color or othercharacteristics of the POP variety print.

The novice should be concerned with carefully following set procedures and methods, controllingconditions as required, and learning, developing and practicing their technique. It is recommendedthat the novice avoid attempting new variations and any modification of procedures or methods.After they fully understand and have mastered the techniques and the procedures of the Pt/Pdprocess, they are no longer a novice.

Steps are to be followed in the order presented.

Basic InformationReady Equipment and Work RoomReady MaterialsReady Stock SolutionsStudy CoatingLearn the ProcessLearn to Make Negative and PrintPhotograph and PrintFurther Study


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Links to more info:

Chapter 1Chapter 2

Links to more info:

Chapter 4Workroom ConsiderationsVendors

Links to more info:

Chapter 5ChemicalsSubstratesVendorsAdditional Information

on metal saltson contrast agents

Basic InformationTo begin, one should first read Chapters 1 and 2.

Now is the time to make the decision and commitment whether to pursuelearning the Pt/Pd process. The cost of acquiring the necessary equipmentand materials can be significant. Again, if one wishes to sample theprocess, it is recommended that they attend a workshop or obtain personalinstruction from an experienced Pt/Pd printer.

While any size negative may be printed by the Pt/Pd process, it is recommended that 4x5 be usedwhen learning. This size is large enough to control and analyze well and small enough to save onchemistry. If one does use smaller negatives, they must keep in mind that coating efficiency andcoverage and the coating itself can be more difficult. The use of a smaller brush for small coatingswill help. If one only has larger negatives, they should consider learning and practicing with a 4x5portion of that negative.

Ready Equipment and Work RoomRead Chapter 4.Purchase any equipment and make any modifications to theworkroom that may be necessary.

Start with the equipment suggested throughout Chapter 4. Aspersonal technique is developed some equipment may be changedor added. If one plans to use the sun as a light source, the artificiallight source need not be built. One should take the time to properlyset up and equip their work space for the Pt/Pd process. Remember to avoid cross contamination,have proper ventilation and lighting, have proper chemical storage, adequate ambient control, andenough space to work comfortably (including a coating area).

Ready MaterialsRead Chapter 5 (except Preparing FO Powder, this is advanced work).Purchase any chemicals and paper necessary.

The following are suggested minimum starting materials and amounts:

distilled water [2 gallons]Ferric Oxalate powder [25 grams]Oxalic Acid [1 gram]EDTA (60-00-4) [1 gram]K2PtCl4 (platinum double salt) [5 grams]PdCl2 (palladium salt) [10 grams]


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Link to more info:

Chapter 6

Links to more info:

Chapter 7Coating CoverageCoating EfficiencyCoating Paper

NaCl, KCl, or LiCl (any one or all) [10 grams each]contrast agent (any one, see info) [1 gram] (optional)Potassium Oxalate [500 grams]Sprint Fixer Remover [1 quart] (for clearing bath)H3PO4 (phosphoric acid, 85%, reagent grade) [1 litter] (optional clearing bath)Bienfang 360 paper [several pads](or Crane's Cover-90)

The quantities given are a minimum. Buying in larger quantities can be more cost effective and isa good idea if one is committed to continuing use of the Pt/Pd process. The quality of the chemicalsis important. All chemicals listed here should be of ACS reagent grade, typically available from anyISO-certified manufacturer (except for the precious metal salts). The metal salts should bepurchased from a special manufacturer such as Engelhard Corporation. However, Engelhard hasa minimum order necessitating the purchase of larger amounts. Smaller amounts may be availablefrom several alternative photography suppliers, although the quality could be suspect.

Other papers may be used, although Bienfang 360 is a good paper to learn coating by brush and isreadily available from most art supply stores. If a rod is used, Crane's Cover-90 will not have thewrinkle problem of Bienfang and is an excellent paper.

Ready Stock SolutionsRead Chapter 6.Prepare stock solutions.

The weighing of materials for the sensitizer, metal salts, and optionalcontrast agent must be done accurately and consistently.Weighing and measuring are the first techniques to master.

Study CoatingRead Chapter 7.Using some water with food coloring added, practice some coating.Follow the sections on coverage and efficiency, but at this point only usethe colored water. Do not use the actual chemistry at this point.This is the beginning of learning brushing or spreading technique.

http://home.att.net/%7Ejeffrey.d.mathias/guide/Chapter7.pdf







































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Links to more info:

Chapter 7Chapter 8Chapter 9Chapter 14

Link to more info:

Chapter 3

Learn the ProcessRe-read Chapter 7.Read Chapters 8, 9, and 14.Mix a coating solution.Coat a paper.Expose using any negative (do not expect this to be a wonderful print).Process.Repeat until the basic process is understood (at this point concentrate onunderstanding the process, not making a wonderful print.)Determine coating coverage and efficiency (this is important.)Try some other negatives that may do better.Coating technique and the procedure of the process should become familiar.Now the novice is ready to begin.

Learn to Make a Negative and PrintRead Chapter 3.Do the exercise and study outlined in Chapter 3.

This will train the eye to read the negative and the print and relate them toeach other and to the original scene. This will also provide the propernegative to use with the materials selected to make a Pt/Pd print suitableto one's preferences. This also provides experience with producing prints consistently.

Having a complete understanding of this exercise will provide a strong foundation for mastering thePt/Pd process.

Photograph and PrintPhotograph, process negatives for the Pt/Pd process, and print.Don't change anything or do anything differently. Just photograph and print.This is the time to perfect technique and begin mastering the process.Remember, the only modifications to be made at this point are in perfecting technique.

Further StudyGot some good prints? Now is the time for Chapters 10 and 11.

Chapters 12 and 13 offer information on negative building. One should realize that they should havea good understanding and command of the Pt/Pd process before building negatives for this process.

The studies in Chapter 15 or their inspiration may lead to advanced work and discovery of newvariations in the process or refinement of procedures.


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AcidsSolventsOxidizersPoisonsUVOther

Chapter 2 - CautionsSafety

With any chemical process care should be given toward safety at all times.Some of the more important considerations will be reviewed here:

ACIDS:

� Always add acid to water. ["Do as you ough-tah, add acid to wah-tah."]

� Always wear safety glasses and gloves and work in a ventilated area.

� Always keep a supply of baking soda or other neutralizing agent available.

� Always pour used diluted acids into a bucket containing baking soda and water to neutralize(this may be checked with PH indicator paper; a value of 7 is neutral), then dilute with morewater, then and only then pour down the drain.

CAUTION: NEVER add the Baking Soda to any strong acid. Doing so can cause a violentspattering. Mix Baking Soda in water, then add acid.

� Acid spills should be cleaned up with an acid spill kit available from most chemicalsuppliers.

� A good precaution is to store all acid bottles, by themselves, in a large plastic tray. If abottle leak occurs, the tray can contain the spill.

� Store acids together in a cool and ventilated place away from all other chemicals.

SOLVENTS:

� There is NO reason to use any organic solvents in the processing of film or platinumpalladium photographs.

CAUTION: NEVER pour any organic solvent down the drain.

NEVER store any solvents in the darkroom or near any acid (mixing of organicsolvents and acids may cause an explosion).


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� All used solvents should be recycled which may be a requirement of local codes.

OXIDIZERS:

>>> POTASSIUM CHLORATE <<<Potassium Chlorate is a very strong oxidizing agent. It can promote combustion with manymaterials. Be extremely careful not to spill the power, especially into rugs or clothing. If spilled,clean up immediately. When measuring this power, lay down a sheet of plastic on the work area soas to contain any spill.

CAUTION: This material WILL spontaneously ignite when combined with some materials.Keep stored in a tightly sealed glass container. It is best to store the container ofpower by itself in a metal cabinet.

>>> HYDROGEN PEROXIDE <<<The 3% solution usually bought at drug stores is fairly harmless. If, however, a stronger solutionis obtained from a chemical supplier, typically 30%, take precautions.

� Hydrogen Peroxide is a strong oxidizing agent and it will naturally release oxygen gas.

� Properly store in a metal cabinet with ventilation to avoid oxygen buildup.

POISONS:

>>> POTASSIUM DICHROMATE <<<>>> AMMONIUM DICHROMATE <<<The Dichromates have the highest health hazard risk of any material one will likely encounter inplatinum palladium printing. They have a rating of 4 on a scale of 0 to 4. Take all precautions toavoid breathing or ingesting the power. (An OSHA approved dust mask must be used for properprotection.)

� Avoid spilling the power. Take precautions by placing a plastic sheet under the weighingand work areas.

� DO NOT get a 0.1% or higher solution on skin or clothing.

� Wear safety glasses and gloves.


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� Always wash hands with plenty of water after handling.

� Although the strengths of Potassium Dichromate in the Potassium Oxalate solution are of0.1% or less and most likely will not cause harm unless ingested or otherwise enters thebody, minimize contact with this solution.

CAUTION: Do NOT submerge a cut hand or finger into developer with even a small amount ofPotassium Dichromate.

>>> HEAVY METAL SALTS AND FERRIC OXALATE POWDER <<<

� Always wear safety glasses and a dust mask when weighing out the powered materials.

� Always work in a well ventilated area.

� It is also a good idea to wear a dust mask and have adequate ventilation when blow dryingthe coating, as some dust may be blown about.

ULTRA-VIOLET LAMPS:

CAUTION: NEVER look at UV lamps or reflected UV light without protective glasses thattotally block UV light. This includes around the sides of the glasses as well. Glacierglasses work well for seeing to dodge and burn.

� Be careful to cover the skin, since these lamps can deliver a good quick sunburn.

� UV lamps can also produce a large quantity of ozone and should be used in a well ventilatedarea.

OTHER:

� Platinum palladium processing requires a good ventilation system in the darkroom (more sothan film processing). Make sure there is good air intake as well as venting out.

� All electrical outlets in the darkroom should have ground fault protection.

� Most working solutions are safe enough to touch, but minimizing contact is a good policy.And, always wash hands with soap and water after handling any chemical or solution.


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� NEVER have food or drink of any kind in the darkroom. Before eating or drinking, leavethe processing area and wash hands with soap and water.

� CLEANLINESS: Cleanliness will make for a safer working environment. It is also anecessity for platinum palladium printing. The slightest trace of hypo or film developer mayshow itself as brown or purple stains on the print. A little film chemistry in the metal saltswill cost a small fortune in lost materials. A little Clearing Bath acid can kill the EnhancingBath. Be careful and clean. Use separate trays: label each tray, and use each trayexclusively for that function only. Keep film processing trays, graduates, and equipment onthe other side of the room from platinum palladium equipment. Do not use the sameequipment for both processes. In an ideal situation, separate sinks and sink areas could beused, one for film processing and another for platinum palladium processing.


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Hazard Ratings and Storage Recommendationsfor Stock Chemicals used with the Pt/Pd Process

Hazard and storage recommendations have been standardized by OSHA (Occupational Safety &Health Administration of the US Government). Each chemical is RATED in each of the followingfour HAZARD categories and provided a STORAGE recommendation.

Material Safety Data Sheets cover and explain more about the use and safety of materials and canbe searched and retrieved at several sites including these: Vermont Safety Information Resources, Inc. Cornell University

HAZARDS: Health - danger or toxic effect if inhaled, ingested, or absorbed Flammability - tendency to burn Reactivity - potential to explode or react violently with air, water, or other substances Contact - danger when exposed to skin, eyes, and mucous membranes

RATING Scale: 4 - Extreme 3 - Severe 2 - Moderate 1 - Slight 0 - No scientific data in standard references that suggests the substance is hazardous

? - Unknown or not rated by OSHA

STORAGE: Blue - Store in a secure poison area. Yellow - Store separately and away from flammable or combustible materials. White - Store in a corrosion proof area. Orange - Store in a general chemical storage area.

The following table includes the most likely stock chemicals involved with the Pt/Pd process.


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Chemical Name Formula HAZARD STORAGE

Health Flammability Reactivity Contact

Ammonium Citrate (NH4)2HC6H5O7 1 1 0 1 Orange

Ammonium Dichromate (NH4)2Cr2O7 4 1 3 3 Yellow

Ammonium Ferric Oxalate (NH4)3Fe(C2O4)3.3H2O ? ? ? ? ?

Citric Acid HOC(COOH)(CH2COOH)2H2O 0 1 0 1 Orange

EDTA CAS:60-00-4CAS:64-02-8CAS:6381-92-6 (HOCOCH2)2NCH2CH2N(CH2CO

OH)2

1 1 0 1 Orange

Ferric Nitrate 9-hydrate Fe(NO3)3.9H2O 1 0 3 2 Orange

Ferric Oxalate Fe2(C2O4)3.6H2O ? ? ? ? ?

Hydrochloric Acid HCl 3 0 2 3 White

Hydrogen Peroxide (3%) H2O2 0 0 1 1 Orange

Hydrogen Peroxide (30%) H2O2 2 0 3 4 Yellow

Lithium Chloride LiCl 2 0 0 2 Orange

Oxalic Acid HOCOCOOH2H2O 2 1 1 3 White


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Chemical Name Formula HAZARD STORAGE

Health Flammability Reactivity Contact

Palladium Chloride PdCl2 1 0 0 0 Orange

Palladium double salt (Potassium) K2PdCl4 1 0 0 0 Orange

Palladium double salt (Sodium) Na2PdCl4 1 0 0 0 Orange

Phosphoric Acid H3PO4 2 0 2 3 White

Platinum double salt K2PtCl4 3 0 0 0 Blue

Potassium Chlorate KClO3 1 0 3 2 Yellow

Potassium Chloride KCl 0 0 0 1 Orange

Potassium Dichromate K2Cr2O7 4 0 3 3 Yellow

Potassium Ferricyanide K3Fe(CN)6 1 0 1 1 Orange

Potassium Oxalate KOCOCOOKH2O 3 0 1 3 White

Sodium Bisulfate NaHSO4 2 0 1 1 Orange

Sodium Chloride NaCl 1 0 0 1 Orange

~~~~~~~ Guide to Platinum Palladium Photographic Printmaking by Jeffrey D. Mathias ~~~~~~~

3.1

Chapter 3 - Negative ControlSensitometrycreated 1993, updated April 2001

The apparent values in a photographic print or negative can be quite different from the actualphysical densities. Part of this is due to the fact that any value will influence the appearance ofanother value it is next to. Another consideration is that a particular value may feel right for thecontext of a particular image.

Knowing the density of a spot on a negative or print is not necessary for producing the highestquality Pt/Pd prints. So too is any line, curve, or number. These terms may be used to talk tough,but that's not a photograph. A d-logE curve will not provide the real information as to how thephotograph is seen or felt. A densitometer will provide a unneeded number at great expense.

Getting an absolute black means nothing. Claims are made that such-and-such is better because itprovides a blacker black (or "it's D-max is better"). Black is not absolute. Even the deepest shadow,even in the middle of the night, is not absolute black, especially with the platinum palladiumprocess. Let it be known right here that if a blacker black is desired, then one should try the gelatinsilver process. Different papers, as well as variations in chemistry, will provide different blacks.It would NOT be wise to select a paper (or worse discard a paper) based only on its blackest value(or D-max). And, surprise, the blackest black in the print will never be the blackest possible withthose materials. (Note: If not surprised, a good amount of printing experience must be at hand.)

Zones (as from the Zone System), like blacks, are also misunderstood. A Zone is a zone. Not aparticular value, a Zone is a range of values. By definition the size of a Zone has been set to therange of values between the relative end points of a one stop range of exposure. The exact value isselected by the photographer for that particular print. A Zone may differ in the next print or withthe next subject. Zones become useful in understanding relative increments of exposure anddevelopment and the relative placement of tonal values.

Might as well continue with a description of whites . With the platinum palladium process, manypapers are available for selection. Each paper will have its own white. Optical brightening agentsmay alter the paper white. The platinum palladium process may not produce a white as brilliant asa gelatin silver print. If that's what is needed, print in gelatin silver. It is sometimes thought thatZone X or XI is paper white. This is not the case, especially with pure palladium. Zones X, XI, XIIand XIII may be distinguished and still not be paper white. The upper values are extremelyimportant to a print. Finding and using the proper materials can make all the difference.

All one needs to know about the sensitometric qualities of film and materials can be had by making,fine tuning, and studying the Matrix described in the next section. Notes of the original scene athand, the Matrix of negatives, and the Matrix of prints all laid out upon the table provide a wealthof information. From these one can see the smallest amount of density that will just separate a tonefrom the darkest density in the print ("speed point", zone I). It can also be seen at what density in


3.2

the film the print will stop exhibiting texture ("contrast point", zone VIII) or just remain as plain aspaper base ("upper limit"). If the print captures the quality that the photographer feels then it mustbe right. So too, the negative may be read as to containing such feeling.

Most importantly, the Matrix is based on a subject of familiarity to the photographer enablingthem to intuitively grasp the nuances of the effects of exposure and development on the materialsselected. To see a photograph, the photographer must know what the print looks like, and what kindof negative produced that print, and what kind of seeing lead to producing that negative. This onlycomes through experience and with much practice.


3.3

= The Matrix = Making a Rough MatrixEvaluating the Rough MatrixFine Tuning the MatrixEvaluating the Fine Tuned MatrixNormalization with the MatrixEvaluation with the Matrix

Simultaneous Exposure and Development Controlcreated 1987, updated April 2001

To expand one's creative ability to the maximum, onemust have a disciplined mind and a disciplined procedure.Disciplining one's mind takes much practice. Adisciplined procedure for the simultaneous control ofdensity and contrast follows.

Note: It is assumed that the reader has a basicunderstanding of the Zone System.Several books are available on this subject.

Making a Rough Matrix of Exposure and Development Times:Each piece of photographic equipment has unique qualities and may produce different results. So,use the equipment that is normally used immutably. The rough version of the Matrix will require12 sheets of film or three rolls (12 frames/roll) of film.

Notes: These amounts are chosen to conserve film. It is strongly suggested to start with theseamounts. More film may be used later to repeat and fine tune the Matrix.

It is important that each sheet film holder is numbered. It will also be helpful if each sheethas a corresponding number exposed onto it.

� Select a subject typical of one's work that satisfies the following: � Neither the subject nor lighting moves. � Zones 0, I, II, VI, VII, VIII, & IX are represented in large areas. � Zones III, IV, V, & X may be present.

Notes: It may help to place some large panels of uniform value into the scene.

The best location for finding all these zones will be where the subject is both indirect sun and deep shadow.

If one's typical source of light is artificial, then use that light instead of the sun.

� The camera is fixed upon a tripod.

� Carefully visualize how the print is expected look, and take notes. Sketch a diagram of thesubject and label the values to be metered later.Note: This is a very important step.


3.4

� Carefully meter the subject:Important: The light meter should be chromatically corrected for film sensitivity, such

as the one available from Zone VI Studios Inc. If not, make sure that allreadings are taken from neutral gray, white, or black cards.)

� Spot meter from as close to the film location as possible. � It is most important to find Zone VIII. � Make sure Zones 0, I, II, VI, VII, VIII, & XI are represented and recorded. � On the sketch made above, indicated all of the metered values.

� Calculate the exposure:

� Use one's presently known film speed or a speed slightly slower.Note: Do not worry if the speed is accurate at this point; the film speed will be

found by evaluating the matrix. Typically the film speed when printing withthe Pt/Pd process is roughly found to be one stop slower than themanufacture's recommendation.

� Use the Zone VIII reading to calculate the exposure.Notes: This is very important.

Remember that meters are calibrated to read everything as ZONE V. Thus,the meter reading of Zone VIII will provide an exposure setting three stopsdifferent from the actual setting required. (Take the meter reading and addthree stops more exposure.)

� Expose film for the calculated exposure and for one stop above and below the meteredexposure.

Exposure

For sheet film: For each roll of the 3 rolls of roll film:

Expose 3 sheets at the calculated setting. Expose frames 1-3 at the calculated setting.

Expose 3 sheets at one stop over thecalculated setting.

Expose frames 4-6 at one stop over thecalculated setting.

Expose 3 sheets at one stop under thecalculated setting.

Expose frames 7-9 at one stop under thecalculated setting.

Reserve 3 sheets unexposed. Do not expose frames 10-12.

Notes: Complete all the exposures as quickly as possible so that the chance of any variationis minimized.


3.5

It is important to note exposure data for each sheet or frame.

Using a constant shutter speed and changing aperture will likely be more accuratethan changing the shutter speed.

Fine tuning will be based on previous results, so the accuracy of data is important.

� Develop film with developer normally used for the time normally used and for times 25%shorter and 25% longer.

Development

For sheet film: For roll film:

Develop one of each of the 3 exposures plusone of the unexposed (4 sheets) for the"normal" time.

Develop one roll for the "normal" time.

Develop one of each of the 3 exposures plusone of the unexposed (4 sheets) for 25% morethan the "normal" time.

Develop one roll for 25% more than the"normal" time.

Develop one of each of the 3 exposures plusone of the unexposed (4 sheets) for 25% lessthan the "normal" time.

Develop one roll for 25% less than the"normal" time.

Notes: If negatives are being produced for the Pt/Pd process for the first time, normaldevelopment should be approximated at about twice the time for silver printing.

A developer should be chosen that has enough strength for the plus developmentsand is fairly linear for time versus concentration.

Keep development times between 3 and 6 minutes (no less than 3 for good uniformdevelopment, and no longer than 6 to reduce base fog). Double or half theconcentration of the developer (and correspondingly half or double the time ofdevelopment) to stay within this 3-6 minute range.(This works well for Kodak HC-110, but may not for other developers.)

For "normal" development of 4x5 Kodak Tri-X 4164 film (using a film speed indexof ASA 200), try a concentration of 64 ml/l (64 ml Kodak HC-110 developer with936 ml water) for 5 minutes. Kodak HC-110 works well at concentrations as highas 256 ml/l and as low as 16 ml/l. It can be used as high as 512 ml/l but may notretain a linear relationship of time and concentration. Below 16 ml/l one must becareful of exhaustion (a possibility would be to use twice the volume if theconcentration is 8 ml/l).


3.6

Tray development is recommended with consistent, continuous, gentile agitation forthe entire development. This helps assure repeatable results.

Development is affected by temperature. Temperature must be constant andstandardized. This means that the temperature not be allowed to change duringdevelopment. Also, the same temperature must be used whenever developing. Forall time! (and at any time of year.) Or, one must re-calibrate (or normalize) theMatrix. The best solution to standardize temperature is to use a temperaturecompensating timer such as the one manufactured by Zone VI Studios Inc.

Keep all other processing conditions constant.

Fine tuning will be based on previous results, so accuracy and consistency areimportant.

� For each development time, determine the exposure to print Maximum Black with theunexposed film. This exposure (for each condition) is called the Printing Exposure.

Notes: Maximum Black is the darkest value that will exist in the print. The MaximumBlack is not the maximum density possible with the materials. An exposure in whichit is thought that there is a distinction between Maximum Black and maximumdensity is close to the proper exposure.

Use the printing method and materials that are typical, because results may vary fordiffering methods and materials.

Do not be surprised if Printing Exposures increase for the plus developments. Thisis most likely due to an increase in base fog.

Procedure to determine Maximum Black or Printing Exposure:

� Trim the edge of the unexposed and developed piece of film with a clean edge (suchas with a good rotary cutter). Use of this edge (away from the original film edge)will help assure an accurate determination.

� Make a typical Pt/Pd coating and place one of the unexposed and developed piecesof film covering half the coated area (use the cut edge of the film as delineation).

� Expose at various times incremented by 0.5 stop intervals (steps). Choose times sothat at least two steps are identical between the areas covered and uncovered by thefilm;

� Process and dry the print.


3.7

� Select the step with the longest exposure that is identical between the areas coveredand uncovered by the film;

� Including and starting with the selected step, make another print with at least fiveexposures at increasing increments of 0.1 stops;

� Select the step with the longest exposure that is close to identical between the areascovered and uncovered by the substrate. This is the Maximum Black. The exposureof this step is the Printing Exposure. This will assure that Maximum Black ispossible in the print with the shortest exposure. The black chosen for MaximumBlack will likely not be the absolute black the materials are capable of producing, butshould be reasonably close.

Figure 3.1 Determining the Printing Exposure to give Maximum Black for the substrate used.The retangular inset is an enhancement in order to better discern differences. Notethe horizontal pencil marks on the sides (marked “s”) indicating the edge of thesubstrate. For this example, the Total Printing Exposure is interpolated to be 5:10minutes (as 4:45 minutes shows lighter, 5:00 minutes shows slightly lighter, and5:15 minutes is about the same). Note that it is typical that the materials producemore density beyond Maximum Black.

� Print each of the exposed films at the Printing Exposure determined for each filmdevelopment time. It is important to be consistent and accurate.

� Evaluate all prints when dry.

Evaluating the Rough Matrix:Negatives should be laid out on a light table such that one axis represents increasing exposure andthe other increasing development. Prints should be laid out the same on an opaque background withgood frontal illumination (similar to display illumination). A decision is now made as to which print


3.8

best represents the subject as visualized to be "normal" before exposure. Interpolate betweenselected exposures and development times if necessary. It is critical to refer to the notes madeduring setup and exposure.

� Zones 0, I, & II will provide information on film speed.� Zones VII, VIII, & IX will provide information on film development.

� Interpolate the "normal" exposure and development. (Print Zone I should be Zone I fromnotes; print Zone VIII should be Zone VIII from notes.)

� Verify that exposure changes corresponds to changes in the print along the exposure axis.

� Calculate N-1 and N+1 development by interpolation along the development axis.

� Rough estimate N-2, N+2, N+3, and N+4 developments by assuming a linear relationshipfollowing the N-1, N, and N+1 developments.

� Rough estimate any exposure differences for the seven developments. Carefully examine theZone I of the plus and minus developments. Most likely these differences will not besignificant except for extreme plus and minus developments.

Fine Tuning the Matrix:Make a new Matrix with exposures of:

none (unexposed film, to calculate printing time)-1 stop-½ stopinterpolated normal speed+½ stop+1 stop

and developments of (as rough estimated):N-2N-1N = interpolated normal developmentN+1N+2N+3N+4

Notes: This will require 42 sheets of film. A smaller Matrix, requiring 30 sheets, may bemade by eliminating the N-2 and N+4 developments.

Remember to make accurate and complete notes.


3.9

Additional fine tuning may include more extreme developments or ½ stepdevelopments.

Fine tuning of the Matrix is only necessary to half exposure stop and halfdevelopment step increments. It is easy to interpolate quarter stop or quarter stepdifferences and difficult to be more accurate with any equipment or processing.

An exposure stop is that difference in exposure which results in a full zone changefor all values (example: from f8 to f11). A development step is that difference whichresults in a full zone change of a Zone VIII value (example: from N to N+1).

Development differences will affect other zones differently (the lower the zone, theless change).

Evaluating the Fine Tuned Matrix:Negatives and prints should be laid out the same as with the Rough Evaluation. A decision is nowmade as to which print best represents the subject as visualized to be "normal". Interpolate betweenselected exposures and development times if necessary. It is critical to refer to the notes madeduring setup and exposure of the fine tuned Matrix.

� Zones 0, I, & II will provide information on film speed.� Zones VII, VIII, & IX will provide information on film development.

� Interpolate the "normal" exposure and development. (Print Zone I should be Zone I fromnotes; print Zone VIII should be Zone VIII from notes.)

� Verify that exposure changes corresponds to changes in the print along the exposure axis.

� Calculate N-2 (optional), N-1, N-1/2, N+1/2, N+1, N+3/2, N+2, N+5/2, N+3, and N+4(optional) development by interpolation along the development axis.

� Estimate N-2, N+4, developments if optional by assuming a linear relationship of the otherdevelopments.

� Calculate any exposure differences for the developments. Carefully examine the Zone I ofthe plus and minus developments. Most likely these differences will not be significantexcept for extreme plus and minus developments.

One should now have the exposure (film speed) and development (time and concentration) criteriafor the materials, equipment, and printing procedure they utilize.

If one makes mature and honest decisions, then one will arrive at the best possible statement of theoriginal, objective interaction of subject and photographer. But keep in mind that when creating


3.10

each photograph, one must be prepared to make slight variations to the exposure, development, andprinting established above because each interaction with a subject can differ.


3.11

Normalization with The Matrixcreated 1987, updated April 2001

Now that one has a Matrix, what if they change equipment, film type, processing, or printingmaterials? Easy, if one has a Matrix. For any change or combination of changes, do the following:

� Select a subject typical of one's work in which Zones I & VIII are represented in large areas.Note: It may help to place some large panels of uniform value into the scene.

� Carefully visualize how the print should look, and take notes.Note: This is a very important step.

� Expose and develop and print for "normal" as determined by the Matrix.

� Compare this print with the Matrix.

� Find the Zone I that matches along the exposure axis.

� Find the Zone VIII that matches along the development axis.

� Calculate the adjustments need to bring this test to "normal".

Example: If Zone I matches the Matrix at "normal" plus half a stop, and Zone VIIImatches the Matrix at "normal" minus half a stop, then, to compensate for thechange of equipment, film, printing, or whatever, decrease the exposure byhalf a stop and increase the development by +1/2.

� To verify, re-photograph the subject with the corrected exposure and development times.

Zones I and VIII should now match the "normal" of the Matrix.

This procedure is really handy whenever a new paper is used with the Pt/Pd process. All theprevious work of making the matrix is preserved and can be utilized.


3.12

Evaluation with The Matrixcreated 1987, updated April 2001

The primary advantage of the Matrix is that one can develop an intuitive feel for both the negativeand the print as well as the results of various processes and materials. Negatives should be laid outon a light table such that one axis represents increasing exposure and the other increasingdevelopment. Prints should be arranged in the same orientation on an opaque background with goodfrontal illumination (similar to display illumination).

� Study the "normal" print.Notes: Remember "normal" only means the print closest to that desired which matches the

original seeing and feeling.)

Studying should include individual values as well as combined effects of values.

� Study the corresponding negative.

� Study the surrounding prints to learn how changes in exposure and development of thenegative result in the print. (If the "normal" print is not surrounded by other prints, then thematrix should be expanded to include those examples.)

� Study the negatives that produced the surrounding prints.

� Photograph and study prints and negatives from various subjects.

� Repeat these steps until the feeling for how a print and negative look becomes second nature.

This technique can be used to gain control over materials and processes to most accurately createthe statement one wishes to make. Before the camera is set up, one can know what materials andprocesses, exposure and development will produce results closest to those desired.


4.1

Chapter 4 - EquipmentNotebooksupdated February 2001

To record the experience learned from many hours and years of platinum palladium printing, it isan excellent idea to keep a notebook of all printing activities. Two notebooks may even work better.One can be used to record all the information learned about the process and any tests that areperformed. The other can be used to record all the information for producing each individualphotograph.

Specific information to record for each negative or print include:

For Negatives: For Prints:

Date photographed Negative NumberLocation and Subject Date printedweather (optional) Paper usedLens Chemistry used for coatingAny other unique equipment SensitizerFilm type Metalseffective film speed (ASA) Contrast AgentsMeter readings and range Type of Drying (Wet or Dry)Filter Ambient ConditionsAperture TemperatureShutter speed Relative HumidityDevelopment (planned) Lamp distance or time of dayDevelopment time (actual) Exposure timeDeveloper concentration (actual) Burning and Dodging informationAny other unique processing info Developer

ClearingAny other unique processing info


4.2

A convenient way to organize negatives and prints is to catalog them as follows.

For negatives: YYMMDD-XX

For Prints: YYMMDD-XX-PP

YY = year of negative exposureMM = month of negative exposureDD = day of negative exposureXX = film holder number (assuming the same film holder is not reused the same day)PP = print number

Each negative and print will have a unique number. It is important to keep tract of the informationfor all prints, even those rejects that are destroyed. Information might be helpful in futureendeavors.

Sample Film Data Record and Print Information Record:

_________________________________ __________Subject Date_________________________________Location

# Range filter f S N lens Development

: @

: @

: @

: @

: @

: @

: @

: @

: @

: @


4.3

Pt/Pd Print Information______________________________________________________ _______________________Title / location Negative #

Print# Paper Chemistry Date Temp Hu mid ity

CoatingDrying light Exp. Time Dodge & Burn Developer Clear

sensitizermlSSS%

PdmlX

PtmlX

contrastagent%CC

yymmdd oF % RH D=dryW=wet

distance(lamps)

or time (sun)min : sec PO P20

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16


4.4

Test For FoggingSafe Lightupdated February 2001

It is generally thought that the platinum palladium process may be carried out in subduedincandescent lighting. Although this may be true sometimes, it is easy for prints to be fogged, oftenwithout the knowledge of the printer. Due to fogging, the author switched from incandescent lampsto low wattage yellow bug lights, and then, due to fogging again, began using a Sodium vapor lamp.Plenty of illumination to see well and no fogging were the results. Some sodium vapor lampsinclude two sets of filters (yellow and red). Use only the yellow filters.

The most critical time for a safe light is during the coating procedure. The mixture seems to be morelight sensitive when wet. Another time to be careful is in the developer and the first clearing bath.It is better to curtail viewing the print until the print is fully cleared than to risk fogging it.

Any work light should be evaluated by the Fogging Test and used only if it passes. A light is onlyconsidered "safe" when it passes the Fogging Test. A Fogging Test is described in Chapter 14.

Positioning the LampThe most important area for bright illumination is the coating area which can also be used forweighing and mixing sensitizer solutions. Walls and ceiling should be painted white. The SafeLamp should be positioned near the coating area so that the light can reflect off the ceiling andprovide enough light at the coating area to clearly read a newspaper. Some of the light will need tomake its way to other parts of the work area such as the printing area and the sink area. Theillumination in these areas should be enough so as to avoid tripping on or bumping into objects andenough to identify clearing baths and such. For large work areas, two safe lamps may be needed.


4.5

Solid Measure - ScaleLiquid MeasureDroppers

Calibrating DroppersAccessories

Measuring Equipmentupdated May 2001

Measuring equipment only needs to be as accurate as necessaryto maintain consistent results from the process. Chemicals forthe coating solutions (sensitizer, metal salts, contrast agents,other) should be measured with an accuracy of 0.01 grams and0.01 ml. Developers and clearing baths can be measured with an accuracy of 1 gram and 0.5 ounce(15 ml). Liquid film chemistry can be measured with an accuracy of 1 ml.

It is recommended to use only glass or plastic for measuring equipment and accessories. Metalshould NOT contact any chemical as some metals (especially iron) can adversely hinder the process.

Solid Measure - Scale

Scale should be accurate to .01 gramThe Ohaus Cent-o-gram quad balance works fine.

Also shown are plastic spoons and funnels and glassor plastic sheet to catch spills.

Liquid Measure

10 ml medicine syringe (accurate to .1 ml) - 21 ml medicine syringe (accurate to .01 ml) - 1100 ml graduate - (glass, accurate to 1 ml) - 150 ml graduate - (glass, accurate to 0.5 ml) - 132 oz glass measuring cup (accurate to 0.5 oz) - 2


4.6

DroppersDroppers (with bottles) (all should be glass and calibrated as

below) - 7+

Calibrating Droppers

Materials:droppers (glass)the small calibrated syringe (1 ml, accurate to .01 ml)masking tapechemical resistant epoxy paintdistilled water

Instructions to calibrate:� determine the amount required to be dispensed� fill syringe to desired amount with distilled water

(distilled is used so as not to contaminate thedropper.)

� remove bulb from dropper� placing finger over narrow end of dropper and holding with large end up, fill with

measured syringe contents� place masking tape on dropper so that edge is at the level of the water and the tape

covers the dropper above the water level. (If a meniscus is seen, measure from thebottom of the meniscus.)

� release water from dropper� mark a line on the dropper at the tape edge using the epoxy paint� remove tape and let paint dry

Using:� fill dropper with solution to above paint line� then empty some solution so that the top of the solution is at the top of the paint line

(If a meniscus is seen, measure from the bottom of the meniscus.)� empty entire dropper into destination� The delivery might be slightly less due to solution sticking to the dropper surface,

but should be very consistent.

AccessoriesSpatula or small spoons to handle dry chemicals (glass or plastic) - 3Stirrer (plastic)Funnels (plastic, with small end so as to fit on the 2 oz dropper bottles) - 2plastic sheet - to catch spills when weighing out dry chemicalsappropriate personal safety equipment - glasses, mask, gloves


4.7

GeneralCoating SolutionsDevelopersClearing BathsOther

Storage Equipmentupdated February 2001

GeneralIn general, the lab should provide storage for each of the hazard storagecategories (see Hazard Ratings and Storage Recommendations). Alsostorage should help prevent cross contamination of materials. This can beaccomplished with four areas.

Pt/Pd chemicals with BLUE and ORANGE storage recommendations:The BLUE materials (which typically involves the Pt salt) may be stored with the Orange materialsif the area is secured as a poison area would be. This should be a cabinet with lock if necessary usedonly for Pt/Pd materials, measuring equipment, and accessories.

Film chemicals with ORANGE storage recommendations:This can be a separate cabinet or shelves for film chemistry and film processing equipment andaccessories.

Chemicals with YELLOW storage recommendations:These should be stored in a separate cabinet away from any flammable or combustible materials.This cabinet should be metal and may require ventilation for some materials.

Chemicals with WHITE storage recommendations:These are typically acids which can be placed in a large plastic tray (to contain potential leaks)under the work sink so that possible fumes may be ventilated with the sink area.

Coating Solutions1 oz Dropper Bottles (dark amber glass, with glass droppers) - 4+2 oz Dropper Bottles (dark amber glass, with glass droppers) - 3Small Light Tight Box to hold the 2 oz dropper bottles containing sensitizer

Developers32 oz Bottles (wide mouth, dark amber, glass, plastic lid) - 8 (2 minimum)

Clearing Baths1 gal. bottle (wide mouth, plastic, for acids) - 3

Otherboxes - to hold cut paper ready for coatinglight tight Bag - for brush storageshelves for accessories and miscellaneous equipment


4.8

Contact Printing Frameupdated May 2001

The contact printing frame holds the negative andcoated substrate together for printing. It can allowviewing of the printout with out losing registration ofthe negative and paper. The old Century contactprinting frames when modified work the best. Tomodify, all that is needed is to have two pieces ofblack vinyl and a piece of thin foam sheet cut to the interior size of the printing frame. One pieceof the vinyl (placed next to the substrate) should have small tabs at each end to facilitate removalfrom the frame. The foam sheet should be thin and soft. Too rigid of a foam sheet will not workas well.

After placing the film and coated paper into the frame, add one of the vinyl sheets (with tabs), thenadd the foam sheet, then the second vinyl sheet, and finally the back. The black vinyl preventsreflections through the back of the paper and provides a humidity barrier and protects the foam sheetfrom wear. The foam sheet provides a good even hold down for assured contact and registration.The felt on those old Century contact printing frames just does not do what the foam sheet does. Forease of assembly, the foam sheet can be glued between the vinyl sheets to enable handling as onepiece; however, only glue in a few places along one end so as to not restrict movement as the piecesare pressed together when closing the back.

It is also important to have a good piece of glass without visual defects. The glass should transmitultra violet and blue light well as this is the light needed for exposure of the coating. The glassshould be thick enough so as not to flex too much when the spring back is clamped shut.

Accessory Equipment:� Cotton gloves For handling negatives� razor blades, glass cleaner, and paper towels for cleaning glass

Diagram of loaded Contact PrintingFrame (not to scale)


4.9

SunUV lampsAdditional EquipmentSun vs UV Lamps

Light Sourceupdated May 2001

Sun:The sun makes an excellent light source if weather conditions permit.Exposure can be in direct sun or in the shade with differing results. Ifin direct sun, a short stick mounted perpendicular to the Contact Printing Frame will indicate whenthe frame is aimed directly at the sun when no shadow is showing. Printing times may varythroughout the year as well as throughout the day. Most consistency can be kept by printing from10:00 am through 2:00 pm. Logging the date and exposure in the Notebook can eventually provideinformation as to the need for any correction for the time of year. For more controlled light andprinting at night or anytime, artificial lamps can be used.

UV Lamps:There are many lamps available for use as UV sources. Themost important aspect is to have uniform intensity in theexposure area. The best way to accomplish this is to havethe illumination source the same size (or larger) as theexposure area. The long tube lamps work well for thispurpose. Several straight tubes may be placed side by sideto make whatever size area desirable . U-shaped tubularlamps may cost less overall, and should be mounted in twolayers one offset above the other (see diagram at right).

Since the Pt/Pd coating is mostly sensitive to ultra violet andblue light, tubes should be chosen that have their maximumoutput in this part of the spectrum. These lamps may bedesignated "BL" or super actinic. It is not immediatelyobvious which lamp will have the highest output. These lamps are ratted by wattage, and it is soondiscovered that the higher the wattage the longer the tube. The highest output lamp can be foundby dividing the wattage by the tube length, and then, comparing this number (the larger, the morepowerful). The trick here is that what is needed is the power output per area. The tube diameter isusually small in comparison to its length, so using just the length will provide an accurate enoughcalculation. Catalogs readily list the wattage and length of tubes.

An excellent U-shaped lamp is the General Electric F40BL/U/3. Six can cover a 20 x 24 inch areaat a distance of 12 inches (or even larger, 30" x 36" with good uniformity at a little further distance).When ordering the lamps make sure to get the proper ballast for the lamps. And, this is a good timeto get the electrical sockets. This way everything should be compatible.

A wooden housing may be constructed for the lamps. If wood is used running a ground wire orgrounded metal strip within proximity of each lamp will help assure proper starting. The inside of


4.10

the lamp housing should be painted with a highly reflectiveflat white paint. This will get more light to the working area.Do not use polished or metal reflectors as this will onlycause non uniformity problems in the exposure area. Theworking area can be painted flat black. The housing shouldbe light tight. A black cloth with 1" to 2" wide Velcroaround the opening will make a good light seal and keep iteasy to open and place the printing frame into the exposurearea. The reason the exposure area should be light tight is sothat the UV light will not interfere with other steps (such asclearing or coating) that may be occurring simultaneously in the same room. Having the exposurearea in a separate room would be helpful especially when dodging on burning with the cloth open,but would require more movement from room to room.

For dodging and burning the cloth will have to be open. During that time make sure no other UVsensitive activities are occurring within proximity. Also protect eyes and skin whenever exposedto the light (see additional equipment below).

Additional Equipment:Glasses that block all Ultra Violet light - These must be used when dodging, burning, or lookingat lamps or the reflected UV light from lamps. Make sure the light is blocked from the sides of theglasses as well such as may be done with glacier glasses or goggles.

Gloves and long sleeves - These will be used when dodging or burning, it is easy to get a burn fromworking under UV lamps. Sun-block may be used, but wash it off hands and fingers to avoid gettingany on the print.


4.11

Sun vs UV Lamps:The following table lists and compares some of the differences between the sun and UV lamps.

Difference Sun UV Lamps

collimated light yes - parallel and sharp no - diffused

spectrum change by atmospheric conditions by lamp type

intensity can vary by hour of day and time ofyear

fairly consistent

availability partial always

reliability by chance high

sharpness high depends on contact

temperature may get very hot cooler than sun

exposure times typically several minutes usually longer than sun

equipment cost minimal (stand and shadow stick) several hundred dollars

exposure control by covering by timer switch


4.12

Processing Equipmentupdated February 2001

SINKLarge sink to contain all wet processing steps. 3x10foot works well for 12x15 inch trays. In a large labwith heavy use, separate sinks for Pt/Pd and filmmay be beneficial.

TRAYSTrays should be a bit larger than the largest paper to be used.Note: 12x15 work fine for 11x14 paper and smaller (8x10 negatives and smaller).Trays should be white plastic with smooth bottoms (no ridges or groves).Note: Ridges or groves may damage the paper, especially thin paper.

� One tray used exclusively for Developer bath (labeled)� One tray for rinse (labeled)� Three trays for Clearing baths (labeled)� One larger tray for pre-washing� One larger tray (or print washer) for washing� One tray for brightening (optional)� Five trays for film (develop, stop, fix, hypo clear, pre-wash) (labeled)

Note: NEVER use any other chemicals, especially film chemistry, in the Pt/Pd trays.Staining of prints can occur.

Print washerThis is optional and only for heavier papers or fabric.

Drying ScreensThese are a must for thin papers

Clips and LineThese are for drying heavier papers and fabrics.

Large Plastic BucketThis is used for neutralizing acids.

Good Ventilation System


5.1

WaterCoating Chem.

SensitizerSensitizer AdditivesMetal SaltsSaltsContrast Agents

Processing Chem.DevelopersClearing Agents

Other

Chapter 5 - Raw MaterialsChemicalsupdated December 2000

Many chemicals are used with the platinum palladium processthat may not be used with other photographic processes. Anychemical should be appropriately stored, handled, and used.Storage and handling recommendations for most of thesechemicals can be found in Chapter 2, Hazard Ratings andStorage Recommendations. Descriptions and notes for their usein the platinum palladium process may be found in this and othersections.

NAMEFUNCTION

DESCRIPTION & NOTES

Tap WaterMaking Clearing Baths and Washing.

If high in iron, clearing will be adversely affected; use bottled water.It is recommended to filter the tap water to 0.5 micron.

Distilled WaterMaking all coating chemistry and developer; rinsing coating brush

From steam distillation or reverse osmosis deionization.

� Coating Chemicals ---_________Sensitizer:

Ferric OxalateSensitizer (used with DOP, developing out process)

Powder should be kept refrigerated and protected from light.Must make up working solution 24 hours in advance. It should last several months.Do not heat nor microwave this solution. Heat may harm it.Keep the working solution cool and dark; but it is not necessary to refrigerate.Light, heat, or time will convert Ferric Oxalate into Ferrous Oxalate.Solution is greenish when ferric and yellowish when ferrous.

Ammonium Ferric OxalateSensitizer (used with POP, printing out process)


5.2

Make up working solution 24 hours in advance. It should last several months.Keep the working solution cool; but it is not necessary to refrigerate.Light, heat, or time may convert Ferric into Ferrous.

_________________Sensitizer Additives:

Oxalic AcidSensitizer additive

White crystals. Clumps with humidity.Studies have found a strength of 3% to 5% to provide better print sharpness.It dramatically helps clearing and reduces clearing times.

EDTASensitizer additive

White powder.It dramatically helps clearing and reduces clearing times.

Note: More information on how individual sensitizers and additives effect the print can be foundin the section Preparing the Coating Solution.

__________Metal Salts:

Platinum [ K2PtCl4 ]Metallic Salt

Red powder or crystal.Any yellow or brown material is K2PtCl6, which is only slightly soluble in water.K2PtCl6 leaves a precipitate in the solution which may result as black specks.Do not heat the solution or the powder to greater than 140oF.Heat can convert it to K2PtCl6 (especially over 140oF).The existence of sodium increases the susceptibility of conversion into K2PtCl6.When in a hot climate, the substituting of potassium for sodium with the palladiumsalt will help prevent black specks in the print thought to be caused by K2PtCl6.

Palladium [ Li2PdCl4, Na2PdCl4, K2PdCl4 or PdCl2 ]Metallic Salt

Brown crystal.The double salts (X2PdCl4) are Hydrophilic making weighing difficult.Less expensive than platinum.Has other advantages too; see mixing coating solution.To get the mixture into solution the first time, it must be heated.Use the double boiler method with hot water (very hot tap water will work).Once in solution it will stay there, except when potassium or supersaturated solutions


5.3

are used, requiring heating before each use.

_____Salts:

Lithium ChlorideSalt

White crystal.This may be used in the palladium solution.When used with Ammonium Ferric Oxalate sensitizer, this salt produces the mostneutral color.When mixed with water, heat is released (exothermic reaction).CAUTION: Solution can get hot to the touch quickly when mixed and may break

a weak bottle.

Sodium ChlorideSalt

White crystal.Table salt works, but prefer use of the more expensive reagent grade.

Potassium ChlorideSalt

White crystal.This may be substituted for the NaCl in the palladium solution to keep Na away fromthe platinum salt. The disadvantage is that the required palladium solution will notstay soluble at room temperature. The solution must be kept warm during each use.

Note: More information on how individual metal salt solutions effect the print can be found in thesection Preparing the Coating Solution.

______________Contrast Agents:

Potassium ChlorateContrast Agent

White crystal. Strongly reactive, see Safety section.A little will prevent fog and controllably increase contrast.The print seems to lose substance without some Potassium Chlorate.Too much will degrade the paper or cause image graininess.Increases exposure time.

Hydrogen PeroxideContrast Agent

Clear liquid; typically a 3% solution.


5.4

Works like Potassium Chlorate, but will not hurt the paper.May cause platinum salt to degrade (especially at higher concentrations).Not as controllable due to its instability. Mixing fresh from stock helps.

Ammonium DichromateContrast Agent

White powder. Health hazard, see Safety section.Supposedly provides true contrast control.

Potassium DichromateContrast Agent

Orange powder. Health hazard, see Safety section.Provides contrast control internally (in coating) or externally (in enhancer.)May give some nice edge effects and sharpness.Edward Weston mentioned in his daybooks that this brought life to clouds.It is used up, the Potassium Oxalate Bath must be kept replenished if used externally.If used internally, some will collect in the enhancer (developer) thus altering it.

Note: More information on how individual contrast agents effect the print can be found in thesection Preparing the Coating Solution.

� Processing Chemicals �__________Developers:

Potassium OxalateDeveloper

White crystal. Endothermic when mixed with water.This developer produces the best depth and substance in the print.To mix, the water should be hot. The reaction of going into solution is endothermic(absorbing heat). The solution cools rapidly hindering further dissolving.This bath should remain acidic for proper results.To maintain a low PH, Oxalic Acid may be added, but is rarely needed.Never allow any HCl, H3PO4, or other clearing bath acid to contaminate this bath.A fresh solution may be seasoned by putting in a couple droppers full of the platinumsolution. Replenish with fresh stock solution as needed, but start over with freshsolution when heavily used to prevent fogging.

Ammonium CitrateDeveloper

This developer produces a very neutral color.But, it can produce a slightly flat looking print.


5.5

Flatness can be avoided while achieving a more neutral color by mixing withPotassium Oxalate (50-50.)

______________Clearing Agents:

Phosphoric AcidClearing Agent

Clear liquid, usually 85% reagent gradeAn excellent alternative to HCl. This bath will not bleach the image and works great.

Hydrochloric AcidClearing Agent

Clear liquid, it is recommended to use the 18-20% solution named Muriatic Acid.High concentration is hazardous and should be used only with the proper equipmentand precautions.This is the traditional clearing bath. But, the traditional clearing times are in error.See section on clearing.Works fine for some papers and fabric, but can bleach the image when using longerclearing times necessary for most of the thicker papers.

Citric AcidClearing Agent

White crystalAn alternative to the other acid clearing agents.

Sprint Fixer RemoverClearing Agent

Liquid colored with blue exhaustion indicator.One of the fastest clearing agents for most papers.

EDTA(Na4)Clearing Agent

White powderSeems to clear only when EDTA and Oxalic Acid are added to the sensitizer.

Sodium SulfiteClearing Agent

White crystal

Sodium BisulfateClearing Agent

White crystal


5.6

Baking SodaNeutralizing Agent

White powderAdd diluted acid (working solution) to baking soda and water to neutralize.Do NOT add straight to any acid. This is NOT intended for acid spills.

Note: More information on how individual clearing agents effect the print can be found in theClearing Study.

� Other Chemicals ---

Potassium FerricyanideTesting Agent

Red or deep red-orange crystalThis will harm platinum-palladium chemistry, even in the tiniest amount.Be careful and clean when using.Store in a location separate from any platinum-palladium chemistry.


5.7

Preparing Ferric Oxalate Powder

This is an illustrated guide to the manufacture of Ferric Oxalate powder of the highest quality asproduced by Vicente-M. Vizcay Castro. Written in August/1999, this guide is available in Spanishand English with the American English adaptation and verification of the process and testing byJeffrey D. Mathias.

Link to Preparing Ferric Oxalate Powder

http://jeffreydmathias.com/guide/FO_intro.htm


5.8

Substratesupdated December 2000

PaperVarious PapersFabricConsiderations

The substrate provides support for the coating and the final resting place for the noble metalsforming the image. But the substrate also can significantly influence the image through its color,surface texture, translucency, and reactions with the chemistry and processing. Selection of thesubstrate is an important decision and there are many substrates to choose from. The best materialfor a substrate seems to be cotton in the form of paper or fabric. Other materials can be usedincluding wood pulp papers, some which can easily rival the best cotton papers. One importantcriteria for substrate selection is archival longevity being that the Pt/Pd process is one of the mostarchival image processes.

PAPER:

Many papers work fine for this process, but many do not. However, some that do not work straightfrom the manufacturer can be made to work. Continuously trying new papers is a good idea.Variations have been found between different production runs of a single paper. It is a good ideathat after a good paper is found, a large quantity of that batch or lot is purchased.

In general:

� Any paper with good tooth and a resistance to bleeding should be tried.� The paper can affect the color of the print.� The thinner the paper, the sharper the image.� The smother the paper, the sharper the image.� Paper may be 100% Cotton Rag, but it may also be an archival wood pulp paper.� Use only a paper who's longevity and quality is worthy of a platinum-palladium

print.

Take heed that some manufacturers are not consistent in their use of raw materials which can leadto batch variations and inconsistencies.

Every paper has two sides (usually referred to as the nap side and the screen side). One side is betterto print on than the other. Sometimes that side is smother. Sometimes that side has less texturewhen dry after being wet. Sometimes that side has better tooth (characteristic to grab and hold ontothe coating). Sometimes that side gives better depth to the print. Sometimes the other side just doesnot work. In any case, find the side that gives the best print and find a way to identify it. There may


5.9

be a watermark, a texture, or a screen mesh impression (when viewed with a loop). The good sidewill always be the good side. Paper is typically packaged with the same side always one direction.In general, paper is manufactured with a nap on the front surface. The nap is generally smother andmore uniform, but many times the back side works better.

Some papers must be candled. They may look great, but have defects hidden inside. The final printalways manages to display this defect as a black speck or spot. (A paper notorious for this isStrathmore 500 Drawing - hard surface or plate.) Place the paper over a light table and if anythingis in there, it can be seen. Coat and print on the "clean" areas of the paper. Another problemindentified by candling can be pinholes.

Click here for some results for various papers.

FABRIC:

It is strongly recommended that one master printing on paper before attempting to print on fabric.This advice can save a lot of expense. Fabric typically requires about three times the chemistry thanthat use with paper.

A high quality 100% cotton finely woven fabric works best. The best are listed here:

� Sea Isle� Pima� Egyptian

Any type of cotton fabric can be expected to work well. Thicker fabrics, such as canvas, can beexpected to require even more chemistry.

It is recommended to use fabric that is pre-shrunk. Registration is already hard enough.

Silk has been found to not work with this process. The acids drive the ferric and metal salts into thefibers where they remain to stain and deter the image. Further research may discover a way to clearthese prints.

Considerations:

The paper or fabric should be cut larger that the negative. Prints may be trimmed when finished.Paper should be cut ahead of time and kept in boxes aligned with the good side up. This will let thecoating step proceed quickly. For some papers and fabric consideration may be given to thedirection of the grain or weave.


5.10

Substrate Sizes:

NEGATIVE RANGE OPTIMUM

Smaller than 4x5 6x7 to 11x14 10x12 4x5 6x7 to 11x14 11x14 8x10 10x12 to 16x20 11x14 11x14 13x16 to 16x20 16x20 Larger than 11x14 16x20 to full sheet full sheet

Note: The size selected should give plenty of room for handling. Remember, if a finger touches the coating, a mark may show up in the print. Consideration might also be made for printing and processing equipment sizes and the cost of the substrate.


5.11

Paper Infoupdated December 2000

PAPERS TESTED TO WORK WELL:(not all papers have been tested)Arches PlatineArtist Drawing Bristol - plate finish (#1 Sulfite)Bee Vellum - 450Bienfang Graphics 360 100% Rag LayoutCanson Vellum / 110 VidalonCranes Distaff LinenCranes Parchment (or Business Card Stock)Cranes Stationary with Kid FinishMirage - plate finish - 2 plyMirage - vellum finish - 2 plyRissing Gallery 100Southworth Parchment DeedStrathmore Alexandra BrilliantStrathmore CarillonStrathmore Tracing ParchmentStrathmore Ultra Marker

PAPERS TESTED TO WORK WELL, BUT ARE NOW DISCONTINUED:Strathmore 500 Artist Drawing, Hard surface (old acidic process)Strathmore 500 Artist Drawing, Medium surface (old acidic process)

PAPERS THAT DO NOT WORK WELL AS RECEIVED FROM THE MANUFACTURER:

NAME REASON

Most Bristles Acid will separate pliesAny Unsized Paper Coating will just soak throughArches Johannot Incomplete clearing, falls apart when wetBee 100% Rag Prepared Tracing #687 Weak print, does not clearBienfang Admaster 406 R Weak print, incomplete clearingCanson Airbrush / coated Does not coat well or clearD'Arches Watercolor HP Does not clearD'Arches Silkscreening No sizing, coating soaks throughFisk C.S.2 Does not clearFisk C.S.10 Incomplete clearingMohawk Superfine (high finish) Coating soaks through, blotchy printMorilla Leonardo 100% Rag Drawing Weak print, mottled


5.12

Multimedia Artboard Weak print, does not clearNeenah Old Council Tree Muddy print, incomplete clearingNeenah Old Council Tree Bond Weak print, incomplete clearingRives BFK FogsSimpson Protocol 100 Week and blotchy printsSomerset Does not clearStrathmore Gemini Watercolor HP Incomplete clearingStrathmore Layout Some coating soaks throughStrathmore Script Coating soaks throughStrathmore Writing (Bright or Ultra) Weak print and incomplete clearing

Please note that with the progress of new techniques and processing some of these papers testedpreviously may now work.

Descriptions of papers which work well with the Pt/Pd process.

Arches Paper Arches Platine Excellent quality, depth, and substance. Very Good detail in print. Excellent surface, good tooth, white color. Easy to coat, no soak through, requires less chemistry that other papers. Must be exposed immediately or black specks will be formed randomly. Floats in clearing baths and wash. Must have a final clearing in Sodium Sulfite.

Artist Paper Artist Drawing Bristol - plate finish (#1 Sulfite) Excellent quality, depth, and substance. Very good detail in print. Hard surface gives plenty of time to coat. Coating must loose glossy look before blow drying.

Bee Paper Bee Vellum - 450 Great quality with a lot of depth and substance. Excellent detail in print. Excellent luminosity from translucency, several thicknesses are available. Translucent, color of print may be changed by colored under mat. Average to coat, but watch for curling.


5.13

Bienfang Paper Bienfang Graphics 360 100% Rag Layout Excellent quality and substance with deep blacks and translucent whites. Thin and very strong, even when wet. Produces the sharpest image. Tends to be slower and lower contrast, and has a very good printout. Translucent, color of print may be changed by colored under mat. Easy to coat, but be careful of wrinkling. Easy to coat, does not need humidification. Quick to dry, but let coating loose gloss. May not be suitable for prints larger then 11x14 due to handling. Finished prints tend to wrinkle with humidity. Can be archival dry mounted (recommended for images larger than 4x5).

Canson Paper Canson Vellum / 110 Vidalon Good quality with a lot of depth and substance. Detail in print is not as good as Bee or Strathmore. Translucent, color of print may be changed by colored under mat. Average to coat, but watch for curling. Prints tend to wrinkle.

Cranes Paper Cranes Distaff Linen Great quality. Nice smooth surface texture. Several colors are available. Difficult to coat, watch for soak through.

Cranes Parchment (or Business Card Stock) Great quality, depth, and substance. Yellowish color may be a problem. (Works well with brightening agents.) Very nice surface, lots of tooth but smooth. Average to coat, Soak through and brush marks are no problem. Very easy to abrade surface, and difficult to spot. Great heavy weight paper.

Cranes Stationary with Kid Finish Great quality warmer image. Nice smooth surface texture. Several colors are available. Difficult to coat, must be very quick, soaks up chemistry quickly.


5.14

Watch for soak through.

Mirage Paper Mirage- plate finish - 2 ply Excellent quality, depth, and substance. Excellent detail in print. Hard surface gives plenty of time to coat. Coating must loose glossy look before blow drying. Plies do not separate throughout wet process.

Mirage - vellum finish - 2 ply Excellent quality with a lot of depth and substance. Great detail in print. Average to coat Plies do not separate throughout wet process.

Rissing Paper Rissing Gallery 100 Good quality, depth, and substance, some detail loss in image. Very white paper base without brighteners. Very nice surface, lots of tooth but smooth. Average to coat. Floats in acid baths and wash. Difficult to spot and easily damaged surface.

Southworth Paper Southworth Parchment Deed Great results for some but not all images, renders good detail. Average to coat, but watch for soak through.

Strathmore PaperThe Strathmore 500 papers mentioned here are manufactured by the "old" acidic process. The new"Acid Free Process" also incorporates a new sizing agent. It is this sizing agent that renders the newversions of these papers unusable. The image will have an overall appearance of a galvanizedtexture, especially in darker areas.

Strathmore 500 Artist Drawing, Hard surface Excellent quality, depth, and substance. Excellent detail in print. Hard surface gives plenty of time to coat, but


5.15

Coating must lose glossy look before blow drying. Difficult paper to coat, especially watch for puddling. If not coated evenly (including brush marks), it will show in print. Use plenty of chemistry and wait for it to soak in, the tendency is to spread the coating out too thinly resulting in a weak print. Must be candled for defects, and there are plenty.

Strathmore 500 Artist Drawing, Medium surface Great quality with a lot of depth and substance. Average detail in print. Texture shows in print, becomes disturbing in larger prints. Easer to coat than hard surface.

Strathmore Alexandra Brilliant OK quality print with some detail loss. Very nice surface, good tooth. Average to coat, no soak through. New Alexandra does not have the sizing problems of Strathmore 500 paper.

Strathmore Carillon Excellent tonal quality, depth, and substance. Excellent surface, good tooth. Average to coat, no soak through, watermark wont obstruct image. New Carillon does not have the sizing problems of Strathmore 500 paper.

Strathmore Tracing Parchment Great quality with a lot of depth and substance. Excellent detail in print. Excellent luminosity from extreme translucency. Translucent, color of print may be changed by colored under mat. Average to coat. Prints tend to wrinkle.

Strathmore Ultra Marker Great quality with a lot of depth and substance. Excellent detail in print. Translucent, color of print may be changed by colored under mat. Average to coat.


6.1

Chapter 6 - ChemistryFormulaeupdated July 1999

Name Formula Description MolarMass orFormulaWeight

Ammonium Citrate (NH4)2HC6H5O7 Developer

Ammonium Dichromate (NH4)2Cr2O7 Contrast Agent

Ammonium FerricOxalate

(NH4)3Fe(C2O4)3.3H2O Sensitizer 428.06

Citric Acid HOC(COOH)(CH2COOH)2H2O Clearing Agent

EDTA (HOCOCH2)2NCH2CH2N(CH2COOH)2

Clearing Agent

Ferric Oxalate Fe2(C2O4)3.6H2O Sensitizer 483.84

Ferrous Oxalate Fe(C2O4) ExposedSensitizer

Hydrochloric Acid HCl Clearing Agent

Hydrogen Peroxide H2O2 Contrast Agent

Lithium Chloride LiCl Salt 42.39

Oxalic Acid HOCOCOOH.2H2O SensitizerAdditive

Palladium Pd Nobel Metal

Palladium (II) chloride PdCl2 Metal Salt 177.31

Platinum Pt Nobel Metal

Phosphoric Acid H3PO4 Clearing Agent

Potassium Chloride KCl Salt 74.55

Potassium Chlorate KClO3 Contrast Agent

Potassium Oxalate KOCOCOOK.H2O Developer

Potassium Dichromate K2Cr2O7 Contrast Agent


6.2

Potassium meta-Bisulfite K2S2O5 Clearing Agent

Potassiumtetrachloropalladium (II)

K2PdCl4 Double MetalSalt

326.42

Potassiumtetrachloroplatinum (II)

K2PtCl4 Double MetalSalt (red)

415.11

Potassiumhexachloroplatinum (IV)

K2PtCl6 UndesirableSlightly SolubleDouble MetalSalt (yellow)

Potassium Ferricyanide K3Fe(CN)6 Sensitizer TestingAgent andclearing indicator

Sodium Chloride NaCl Salt 58.44

Sodium Sulfite Na2SO3 Clearing Agent

Sodiumtetrachloropalladium (II)

Na2PdCl4 Double MetalSalt

294.19

Water (Distilled) H2O


6.3

Process Equationsupdated December 2000

DOP - Ferric OxalatePOP - Ammonium Ferric Oxalate

The process equations help provide an expression of the chemical reactions and an expectation ofthe materials necessary to provide for predicted outcomes. Unfortunately, the reactions and theseequations are not fully understood. Future research may provide better understanding and insightas to the Pt/Pd process.

There are two primary processes to consider:DOP - Develop Out Process employing the sensitizer Ferric OxalatePOP - Printing Out Process employing the sensitizer Ammonium Ferric Oxalate

Current understanding seems to indicate that the metal salts behave similarly and each sensitizer getsto the same outcome by a different route.

The most useful information from the process equations for the process as described in this guideare the ratios of metal salts to sensitizer required. The ratios have been discerned empirically in theEmpirical Verification of Process Equations.

Process Equations for Ferric Oxalate:

The sensitizer reacts to light, heat, or time as follows:

3Fe2(C2O4)3�6H2O >exposure> 6Fe(C2O4)) + 3(C2O4)) + 6H2O

The metals are released by what is known as Brewster's Reaction described by Berkeley's equation:

6Fe(C2O4)) + 3K2PtCl4 => 2Fe2(C2O4))3 + 2(FeCl3) + 6KCl + 3Pt

The same occurs for Palladium:

6Fe(C2O4)) + 3Na2PdCl4 => 2Fe2(C2O4))3 + 2(FeCl3) + 6NaCl + 3Pdor

6Fe(C2O4)) + 3K2PdCl4 => 2Fe2(C2O4))3 + 2(FeCl3) + 6KCl + 3Pdor

6Fe(C2O4)) + 3Li2PdCl4 => 2Fe2(C2O4))3 + 2(FeCl3) + 6LiCl + 3Pdetc.

Every three Fe2(C2O4)3 will pair with three K2PtCl4 or Na2PdCl4 or K2PdCl4 or Li2PdCl4, a ratioof one-to-one (1 metal salt for 1 sensitizer.)


6.4

Process Equations for Ammonium Ferric Oxalate:

The sensitizer is thought to react generally as follows:

(NH4)3Fe(C C2O4)3�3H2O >exposure> Fe(C2O4)2 + 3(NH4) + 3H2O + 2CO2

Some of the (C2O4) is changed into the 2CO2 gas as suggested by Mike Ware.For a description of the reactions by Mike Ware click here.

The basic process reaction for AFO with Lithium is thought to be:

3Fe(C2O4)2 + 3Li2PdCl4 + 3(NH4) + 3H2O =>(NH4)3Fe(C2O4)3�3H2O + 2(FeCl3) + 6LiCl + 3Pd + 3(C2O4)

Or other metallic salts could be substituted.

Every three sensitizer molecules will pair with three metallic double salt molecules, a one-to-oneratio (1 metal salt for 1 sensitizer.)


6.5

Formulas for Ferric Oxalate Sensitizer Solutionscreated May 2000, updated April 2005

In order to achieve accuracy and consistency, it is important to begin with an accurately formulatedsensitizer to which the metal solution will be balanced.

Summaries of Various Studies

The Initial Comparison of FO Powders Study provided estimates for the concentration of FerricOxalate (FO) in several tested FO Powders.

The Verification of FO Powder Composition study used the work of Dick Stevens to relate thepercent concentration of Ferric Oxalate in a solution with its specific gravity. It was found that theStevens' model and specific gravity information may not accurately relate to the concentration ofFerric Oxalate. However good comparisons could be achieved by comparing the resulting prints.

The Initial Threshold Study for FO Solutions determined an optimized sensitizer solution as having26% ferric oxalate when optimally coated onto Cranes Parchment paper (CP). Further studiesresulted in estimated purity and optimized sensitizer solutions as in the following table. It iscurrently speculated that a 100% pure FO powder will have an optimal solution strength between24% and 25%.

FO estimated purity optimized solution strengthassuming 100% pure

Ultra pure Vizcay powder 98% - 99.5% pure 25%

Artcraft powder* ~ 95% pure 26%

Bostic and Sullivan powder* 89% - 91% pure 27%*Important Note:

The Artcraft and Bostic and Sullivan powders were from batches made in the 1990s. Currentbatches of these powders should have their threshold checked by making prints as per theRelative Comparison study.

The study of the Oxalic Acid Concentration in the FO Sensitizer determined a benefit of havingOxalic Acid in the sensitizer solution at a concentration between 2% and 5%.

The Clearing Study resulted in a recommendation for the addition of 0.04% EDTA (CAS: 60-00-4)and about 3% Oxalic Acid to the sensitizer solution to facilitate efficient clearing.

This information has been built into the FO Sensitizer Formula Calculator. Use this calculator orthe Quick Formula Table to determine the formula for a FO based sensitizer solution.


6.6

Optimized Formulas for Metal Solutionsupdated December 2000

Where the optimizations come from is in figuring the ratios of metal to sensitizer needed to balancethe process equations. It can be demonstrated (see studies) that too little chemistry will adverselyaffect print quality and too much chemistry will go unused and be wasted. Also there is much betterconsistency of performance when interchanging solutions if those solutions are optimized.

To accomplish this balancing, the molar concentration of the sensitizer solution is calculated fromthe percent value of the solution and the molar mass (formula weight) of the material. With the massbeing conserved, using the process equation ratio, the molar mass is calculated for the metal doublesalt (MDS). From the molar mass of the MDS is calculated the molar concentration, and then thepercent of the MDS solution. (For an explanation of molar concentration and percent see Makinga Percent Solution.)

The ratios for the process equations have been empirically verified to be 1:1.

The optimum solutions for the metal double salts (MDS) are calculated from the equation:

(% MDS solution)=(fw MDS)/(fw sensitizer)*(ratio)*(% sensitizer solution)

where,fw = formula weight or molar massratio = (molar mass MDS)/(molar mass sensitizer) from the process equation

NOTE: The molar mass for various chemicals are listed in the section, Formulae.

For the palladium (Pd) double salts, each molar equivalent of Pd MDS is mixed from one molarequivalent of PdCl2 and two molar equivalents of the appropriate alkali-chloride salt (salt). Thesolution concentrations of PdCl2 and whichever salt are calculated as follows.

(% PdCl2 solution) = 1*(fw PdCl2)/(fw sensitizer)*(ratio)*(% sensitizer solution)

(% salt solution) = 2*(fw salt)/(fw sensitizer)*(ratio)*(% sensitizer solution)

To begin calculations, a sensitizer and it�s solution strength are required. Keep in mind that thereis a threshold at which point the print has attained its threshold of maximum ability.

Ferric Oxalate (FO) has been traditionally mixed to a solution concentration of about 27%. Higherconcentrations of FO may be mixed with the addition of EDTA to the solution as has been suggestedby John Melanson and Richard Sullivan. FO solutions as high as 32% have been made with theaddition of 4% EDTA(Na4). However, the higher concentrations along with the appropriate metalsolutions do not provide for any further improvement in the print; as the threshold has been passed.Working through the Threshold for DOP Solutions Study can determine the concentration at which


6.7

point prints show no further improvements.

Ammonium Ferric Oxalate (AFO) can readily be mixed to solution strengths of 60% but a thresholdis also encountered of the maximum amount of metal that can be placed into the coating such thatany additional amount will not result in a noticed benefit to the print. This threshold is also afunction of the paper, coating efficiency, and technique. For the Crane's Parchment Business CardStock (AKA: Cover-90 or CP) this threshold has been found to be the amount produced with acoating mixture based on a 35% solution of AFO as determined by the study Verification ofOptimized Formulas (Threshold for POP solutions).

A further consideration is the purity of the FO powder. Adjustments should be made to reflect theaccurate amount of FO involved. The FO Sensitizer Formula Calculator considers the purity ofvarious FO powders based on studies identified in the section, Formulas for FO Sensitizer Solutions.

Some of the metal solutions will not stay dissolved at typical laboratory temperature and pressure,so heating of the solutions may be required. An optional half strength solution (which might notrequire heating) can be calculated and used with the double Quasi Muti-Coating Method.

Notes: Instructions for mixing are included in the section Preparing the Stock Solutions.

Be sure to label all solution bottles with the particular strength sensitizer they are optimizedfor as well as the name of the solution.

To determine the Sensitizer Solution Formula use the FO Sensitizer Formula Calculator.

To determine the Metal Solution Formula use the Metal Solution Formula Calculator.

Both calculators require a JavaScript capable browser.

Or, use the Quick Formula Table below.

The following Quick Formula Table has been created for some specific situations. Note that the25% sensitizer solution column should be used for most DOP situations. The FO amounts to weighout have been adjusted to account for the purity of the FO powder used. The sensitizer solutionpercent numbers assume 100% pure FO. The studies indicated that a 100% pure FO powder has athreshold sensitizer solution strength of 25%. The 26% and 27% solutions are provided if onewishes stronger solutions with more metal. It is not recommended to use less than a 25% solutionstrength FO. (Note: Even if the actual threshold is suspected to be between 24% and 25%, the 25%assures being at or past the threshold with the accuracies involved.)

For POP, 35% is the optimum solution strength for AFO.

http://jeffreydmathias.com/guide/formulae_calculator.htm

http://jeffreydmathias.com/guide/formulae_calculator_FO.htm


6.8

Quick Formula TableSensitizer Solution Strength � � 25% � 26% 27% 35% 35%

Material grams to make 50 ml

DOPSensitizer1

98% FO powder 12.76 13.27 13.78

95% FO powder 13.16 13.68 14.21

90% FO powder 13.88 14.44 15.00

oxalic acid 1.00 1.00 1.00

EDTACAS: 60-00-4

0.02 0.02 0.02

Pt K2PtCl4 10.72 11.15 11.58

Pd2 PdCl2 4.58 4.76 4.94

LiCl2 2.19 2.28 2.37

KCl2 3.85 4.01 4.16

NaCl2 3.02 3.14 3.26

POPSensitizer

AFOamm oniu m fe rric ox alate

17.50 half strength solutions3

Pt K2PtCl4 16.97 8.49

Pd2 PdCl2 7.25 3.63

LiCl2 3.47

KCl2 6.10 3.05

NaCl2 4.781) Only one FO is selected.2) Only one of the salts is mixed with the PdCl2. Li, K and Na salts can only be exchanged if

their relative weight ratios are maintained.3) Solutions which are not completely dissolved at the ambient temperature must be heated in

a hot water bath to completely dissolve all material prior to each coating mixing operation.Do not heat the platinum solution above 140oF. An alternative half strength formula (whichmight not require heating) may be used with the double Quasi Muti-Coating Method.


6.9

Making a Percent Solution

A convenient way to express the mixture of a soluble chemical completely dissolved in water is asa percent solution. This is done by weighing out a desired amount of dry chemical and adding waterto produce a total given volume.

The following excellent description of solution preparation may be found at the link below."Preparation of Solutions for the Clinical Laboratory: A Tutorial"authored by Kereem M. D. Marlowhttp://www.utmem.edu/allied/Solutions/Home.html

Do keep in mind that any material will only dissolve to a certain maximum percentage for a giventemperature and pressure. Assuming adequate solubility, the following examples demonstrate howto make a percent solution. (Errors assume using a balance of accuracy 0.01 gram for the solid anda liquid measure accuracy of 0.05 ml.)

example A) To make a 20% solution, weigh 20 grams of soluble solid into a container, then addwater to make a total volume of 100 ml.

example B) To make 60 ml of a 10% solution, weigh 6.00 grams of the soluble solid into acontainer, then water to make a total volume of 60 ml.

Accuracy:For smaller quantities, it is more accurate to start with a stronger solution and dilute.

example C) To make 30 ml of a 0.5% solution, make a 10% solution, then add 1.50 ml of the 10%solution with 28.50 ml water.

30 ml of a 0.5% solution would require 0.15 grams. Weighed on a scale accurate to 0.01 grams, thiswould have an error of +-6.67%. In example C, a pipette accurate to .05 ml would produce an errorof +-3.33%.

It would be even more accurate to work with larger quantities:

example D) To make 30 ml of a 0.5% solution, make a 10% solution, then make a dilution to 2%and then use that to dilute to 0.5%.

For example D, error to make 100 ml of a 10% solution is +-0.1%; error to then make 100 ml of a2% solution is +-0.25%; error to then make 30 ml of a 0.5% solution is +-0.67%. Assumingcumulative error, the total error would be +-1.02%.


6.10

It is important to always label a bottle as to its contents and the % solution.

Weights and liquid measures and their symbols used in this document:

Liquid (volume) measure Weight measure

ml = milliliter g = gramliter = 1000 ml

oz = ounce = 30 ml gal = gallon = 128 oz


6.11

Weighing Out Dry Chemicalsupdated February 2001

General Informationfor Coating Solutionsfor Developers

General Information:Dry chemicals must be accurately weighed in order to assure reliable and repeatable results. Theaccuracy depends of the sensitivity of the process to that particular aspect and the amount beingprepared. The two procedures outlined below deal with small amounts (such as coating solutions)and large amounts (such as developers).

A scale capable of measuring .01 grams should be used for coating materials since the quantities aretypically in the 1 - 10 gram range. This should allow for a accuracy of 1% or better.

The scale should have the ability to compensate for a large tare (the weight of an empty bottle). Agood choice is the Ohaus Centogram balance scale.

Note: If one has a choice of a powder or a crystal, they should consider using the crystal as thiswill be less likely to get into the air and blow around the room.

PROCEDURE FOR WEIGHING COATING CHEMICALS:

The first time (optional):

� Balance the scale (empty, zero reading)� Weigh the empty dropper bottle (complete with cap and dropper) and record as its weight.

This information may be convenient if the weight of the contents needs to be measured later.

In every case:

� Place a small funnel into the top of a dropper bottle.� Set the bottle with funnel onto the scale platform.� Balance the scale by adjusting its weights. (This is the tare weight.)� Adjust the scale weights to add the weight to be measured minus one gram.� Scoop the dry chemical from its container with a CLEAN plastic spatula or spoon .� Add the chemical to the bottle until the balance just swings over.� Adjust the scale weights to add the one gram left out earlier.� Add more chemical slowly until balanced, by tapping the spatula or spoon with a finger.

Notes: Be careful not to not go past the balance point because the chemical should not be


6.12

returned to the stock bottle from the dropper bottle. If extra is to be removed, treatit as a spill (see below). Also be careful and add slowly, if this is an additionalchemical to that already measured. The order of weighing and mixing the stocksolutions should be followed as stated in this guide since the chemicals added last arethe least likely to cause a problem if a bit too much is added. Return any chemicalremaining on the spatula or spoon to its original container.

Most scales give a more accurate measurement when they are moving slightly backand forth around the balance mark.

� Tap the funnel to make sure all material has been delivered into the bottle.� At this point one is ready to add the appropriate amount of another dry chemical or water.

SPILLS:Do not return or use any chemical that has spilt. It may be contaminated and ruin the entire supply.If a large amount is spilt or valuable material is spilt, it can be placed into a separate storage bottle,labeled, and used to make a solution. This solution should be tested first to see if it works all right,otherwise dispose of properly or recycle to a manufacturer. Do not mix this solution with normalstock solutions.

NOTE: The platinum palladium process is an extremely sensitive process.Any contamination should be avoided.

PROCEDURE FOR WEIGHING DEVELOPER CHEMICALS:

� Place a cup (plastic or glass) large enough to contain the chemical onto the scale platform.� Balance the scale by adjusting its weights. (This is the tare weight.)� Adjust the scale weights to add the weight to be measured minus one gram.� Scoop the dry chemical from its container with a CLEAN plastic spatula or spoon .� Add the chemical to the cup until the balance just swings over.� Adjust the scale weights to add the one gram left out earlier.� Add more chemical slowly until balanced, by tapping the spatula or spoon on the handle

with a finger.� At this point one is ready to pour the chemical from the cup into a large mouth bottle and add

the appropriate amount of water.


6.13

Sensitizer SolutionsContrast AgentsMetal SolutionsDevelopersClearing Agents

Preparing the Stock Solutionsupdated December 2000, note added 8/2001

In order to efficiently coat and process a print, stock solutions areprepared from the bulk materials. The information below indicates theitem, the component chemicals (listed in the order mixed), their weightsor amount, and a procedure.

Water being of many qualities, the following notations have been chosen for this guide.

Water = Tap water filtered to 0.5 micronH2O = Distilled Water (by steam distillation)

Note: A convenient way to view the contents of a amber bottle is with a sodium vapor lamp. Holdthe bottle in front of the light and the bottle will seem to be clear.

Descriptions of the chemicals can be found in the Chapter 4, Chemicals.

Sensitizer Solutions:The formula depends on the actual amount of ferric oxalate in the sensitizer powder discussed inthe section on Sensitizer Formulas, the amount of Oxalic Acid from the Oxalic Acid ConcentrationStudy, and the amount of EDTA from the Clearing Study.

The resulting formulas may be produced with the Sensitizer Solution Formula Calculator. Moreinformation on how an individual sensitizer effects the print can be found in the section Preparingthe Coating Solution.

Warning: Dust may be harmful; wear protective mask and clean up any spills.Sensitizers typically have a pH of 0.1 to 0.3 and may etch the skin of unprotectedhands; avoid contact.

NOTE (added 8/2001): Further study of the "bleeding" of metal during processing has indicated thattoo much EDTA seems the culprit. It is now recommended that EDTA in the sensitizer be kept toa solution strength between 0.04% and 0.1%. The actual amount can vary with different papers, sothe smallest amount of EDTA to add to the sensitizer to assist with clearing should be determinedfor each paper.


6.14

Contrast Agents:A few on the agents are listed here. More information on how individual contrast agents effect theprint can be found in the section Preparing the Coating Solution.

Warning: Powder of some contrast agents may present fire hazard; store properly and clean upany spills.

Metal Solutions:The strength of the metal salt solutions depend on the sensitizer solution used and are to bedetermined by using the Metal Solution Formula Calculator. Some mixtures may be found in thesection on Optimized Formulas. More information on how individual metal salt solutions effect theprint can be found in the section Preparing the Coating Solution.

Warning: Dust may be harmful; wear protective mask and clean up any spills.

Developers:

Warning: Dust may be harmful; wear protective mask and clean up any spills.

Clearing Agents:The agent and times for clearing should be found as necessary to pass the Clearing Test. Moreinformation on how individual clearing agents effect the print can be found in the Clearing Study.

Warning: The following acid strengths may etch the skin of unprotected hands; keepimmersion time of hands limited and rinse hands in water immediately afterimmersion.


6.15

Solution Abbreviation Chemical Component Amount Directions to Mix

SENSITIZER

DOP Sensitizer FO Ferric Oxalate ***** In Safe Light,Weigh out dry chemicals into bottle,Add H2O & Shake well every 4 hours,Should be dissolved in 24-36 hours.Do not use until completely dissolved.Do NOT use high heat nor microwave.

Oxalic Acid *****

EDTA (CAS: 60-00-4) *****

H2O *****

POP Sensitizer AFO Ammonium Ferric Oxalate ***** In Safe Light,Weigh out dry chemicals into bottle,Add H2O & Shake well,Should sit for 24 hours before using.Do NOT heat nor microwave.

H2O *****

CONTRAST AGENTS

Contrast Agent PC Potassium Chlorate � Make 15 ml of each of the solutions:0.125%, 0.25%, 0.50%, 1.00%, 2.00%with H2O in 1 oz dropper bottles.H2O �

Contrast Agent <internal control>

PD Potassium Dichromate � Make a 2.0% solution with H2O,then Make 15 ml of each of the follow solutions withH2O in 1 oz dropper bottles:0.125%, 0.25%, 0.50%, 1.00%, 2.00%

H2O �


6.16

Contrast Agent <external control>

Potassium Dichromate � Make a 10.0% solution with H2O,then mix with Potassium Oxalate developer to makethese solutions in 32 oz wide mouth bottles: 0.20%, 0.10%, 0.05%, 0.02%, 0.01%

Potassium Oxalate �

H2O �

Contrast Agent AD Ammonium Dichromate � Make a 3.0% solution with H2O,then Make 15 ml of each of the solutions with H2O in 1oz dropper bottles:0.125%, 0.25%, 0.50%, 1.00%, 2.00%, 3.00%

H2O �

Contrast Agent Hydrogen Peroxide (3%) � Dilute as needed immediately before using.

H2O �

METAL DOUBLE SALT SOLUTIONS

Platinum solution Pt K2PtCl4 ***** Weigh out chemicals into bottle,then add H2O.Heat in a warm water bath (<140oF) and shake.H2O *****

Palladium solutions K,Li,or Na

PdCl2 ***** Weigh out chemicals into bottle,then add H2O.Heat in a warm water bath (<140oF) and shake.KCl2, LiCl2, or NaCl2 *****

H2O *****

DEVELOPERS

Developer PO Potassium Oxalate 283 g Warm H2O in hot water bath,Put warm H2O into a 32 oz wide mouth bottle,Add the Potassium Oxalate, and stir,Ready to use when fully dissolved.

H2O 30 oz


6.17

CLEARING AGENTS

Clearing Agent Phosphoric Acid (ACS grade, 85%)

2 oz Put 3 quarts water into a gallon bottle,Into 32 oz measuring cup put 30 oz water,Add 2 oz acid to water in cup,Add contents of cup to water in gal. bottle.water 1 gal.

Clearing Agent Muriatic Acid (20% HCl) 3 oz Put 3 quarts water into a gallon bottle,Into 32 oz measuring cup put 29 oz water,Add 3 oz acid to water in cup,Add contents of cup to water in gal. bottle.

water 1 gal.

Clearing Agent Citric Acid 20 g Add Citric Acid to water, stir until mixed.

water 1 litter

Clearing Agent EDTA(Na4) 20 g Add EDTA(Na4) to water,stir until mixed.

water 1 litter

Clearing Agent Sodium Sulfite 20 g Add Sodium Sulfite to water,stir until mixed.

water 1 litter

Clearing Agent Sprint Fixer Remover 1 part Mix as per label instructions.

water 9 parts

Clearing Agent Sodium Bisulphate 20 g Add Sodium Bisulfate to water, stir until mixed.

water 1 litter

***** indicates to use data from the calculators or the Quick Formula Table.


6.18

Make StrongerMake Weaker

Modifying an Existing Solutioncreated August 1999, updated December 2000

It is advantageous to be able to modify a solution to a stronger or weakerconcentration. The reason for this may be to recycle solutions to updatedformulas or to fix incorrectly measured solutions. For a description ofsolution preparation see Making a Percent Solution.

To make a solution STRONGER:

Example: to modify a 10% solution to be a 12% solution.

� Measure the volume of the existing solution.

Example: 50.0 ml

� Calculate how much material is present in the solution using the following equation:(grams in existing solution) = (% of existing solution) * (ml of existing solution)

Example: (5.00 g) = (0.10 g/ml) * (50.0 ml)

Note: The % is expressed as a decimal, such as 10% = 0.10

� Calculate how much material to add using the following equation.(grams to add) =[(% of desired solution) * (ml of existing solution) * (1.10)] - (grams in existing solution)

Example: (1.60 g) = [(0.12 g/ml) * (50.0 ml) * (1.10)] - (5.00 g)

Note: The 1.10 factor is used to create a larger volume thus compensating for any errorcaused by any increase in volume due to the material added. This factor should befine in most instances. If the amount of material added is very substantial then thisfactor may be increased throughout this procedure. This factor may also beincreased to produce a larger volume of the desired solution.

� Weigh out material. (see section on Weighing Out Dry Chemicals)

� Add material into the solution.

� Mix and wait for all material to be completely dissolved (warming if necessary.)

� Add H2O to bring the volume to 1.10 times the original volume and mix.

Example: Makes 55.0 ml final 12% solution for the factor of 1.10


6.19

The concentration of the solution is now that desired with a volume of 10% more.

To make a solution WEAKER:

Example: to modify a 10% solution to be an 8% solution.

� Measure the volume of the existing solution.

Example: 50.0 ml

� Calculate how much material is present in the solution using the following equation.(grams in existing solution) = (% of existing solution) * (ml of existing solution)

Example: (5.00 g) = (0.10 g/ml) * (50.0 ml)

Note: The % is expressed as a decimal, such as 10% = 0.10

� Calculate how much H2O to add using the following equation.(ml H2O to add) =[(grams in existing solution) / (% of desired solution)] - (ml of existing solution)

Example: (12.5 ml) = [(5.00 g) / (0.08 g/ml)] - (50.0 ml)

Note: Since no solid material is being added, there is no offset in volume.

� Measure out the volume of H2O to add.

� Add H2O to the solution.

The concentration of the solution is now that desired.


7.1

Info links:

Preparing the Coating MixtureCoating CoverageCoating EfficiencyCoating PaperCoating FabricDrying the CoatingWet Dry Drying StudyQuasi Multi-Coating MethodClearing StudyVerification of Optimized FormulaeThreshold for FO Solutions

Chapter 7 - CoatingThe CoatingDecember 2000

The Coating is the most important element of a platinumpalladium print. Technique, paper, exposure, processing,finishing, all contribute important elements to the finalprint. But none are as significant as the Coating. TheCoating consists of solution preparation, mixing,understanding coverage and coating efficiency,application technique and experience, and drying. It is themost labor intensive, skilled craft, and controlled art at theheart of the Pt/Pd process. If one is to master the Pt/Pdprocess, they must master the Coating. The variouselements of Coating are contained in several sections(Chapter 7) and studies (Chapter 15) throughout thisguide. One must also keep in mind that other parts of theprocess may influence Coating, such as to assure efficientclearing, additives are given to the Coating.


7.2

Preparation EquipmentBrushing EquipmentDrying EquipmentGeneral Equipment

Coating Equipmentupdated February 2001

Preparation Equipment:

Tape (optional)Used for writing on fabric.

PencilUsed to mark area to be coated or identify print.

Sonic MisterMost paper should be humidified to get the best coating results. This may be noticed asincreased substance within the print. The humidity seems to open the pours of the paperletting the chemistry soak in better and more completely. Some thin papers like Bienfang360 do not require humidification (in fact, if too humid, this paper will have a curlingproblem). The sonic mister is preferred to steam because all papers coat better when they arecooler.

Shot GlassesThese are convenient to mix and hold coating solutions; have several.

Hot Plate (Coffee Warmer)This is used to keep some of the metal solutions dissolved.

Brushing Equipment:

Brushes, White SableneThese brushes have soft, thin, nylon bristles. The chisel type, wide and thin, arerecommended.

The brush is a most important tool for this process. Too large of a brush will soak up thecoating. Too small of a brush will take too long to brush on the coating.

Red Sable brushes work fine, but are expensive. Any other brush will probably giveproblems. White sablene is actually a very fine nylon (and relatively inexpensive). Thistype of brush along with Red Sable is very soft. Take a brush and rub it on the back of thehand (feel how soft). What happens is that other brushes will abrade some or all of the paper


7.3

fibers when coating. This shows up in the print as patchy textured areas. The foam brushesare some of the worst to use. A glass rod (as mentioned in some texts) may not press thechemical coating into the paper as will a brush. This might result in blotchy areas in theprint. Also, glass rods may catch a dirt speck and scratch the paper, whereas a brush willpick up the speck. However, glass rods have been and are successfully used by manyprinters. Dipping the paper into a coating solution is not practical since it can waste mostof the chemistry.

recommended sizes:0.5" for 4x5 or smaller1" for 4x5 to 8x101.5" for 8x10 to 11x142" for 16x20or two or more in jig for larger than 11x14

Small tray for soaking coating brushThis tray MUST be dedicated to this function ONLY.

Drying Equipment:

Blow Drier (hair drier)A must for drying coatings. A two speed, two heat drier is versatile. A no heat setting is amust. An accessory worth trying is a diffuser (especially if drying fabric or large prints).Two things to be very careful of are: Do not blow on the coating until the gloss has vanished(this may cause puddling and can show up in the print as light blotchy areas). Do not getcoating too hot (140oF can be too hot and may be demonstrated in the print as deterioratedquality).

Clothes Pins or Clips and LineThese are used for drying or for holding wet fabric temporarily. Stainless steel (do not touchwet coating) or plastic are suitable.

General Equipment:

Paper TowelsUseful to squeegee brushes or clean spills.

Glass Plate or Plastic SheetsTo protect table from coating spills or overruns. These are definitely a necessity whencoating fabric. Optionally, a pad of newsprint could be used when coating paper.

Light Tight Container (such as a 4x5 film development tank)This is useful for storing the bottles of sensitizer solutions.


7.4

Coating ComponentsSensitizerMetal saltContrast AgentMixingCoverageExpectationsNotation

Preparing the Coating Solutionupdated December 2000

There is a lot of art in the making of the coating solution. (Thechemical solution is not an emulsion.) Many choices are at hand toinfluence the look of the print. Some general tendencies aredescribed below, however one must try things for themselves todiscover the nuances they prefer in a particular print.

Note: All coating and mixing must be done in safelight illumination.It is important to check if the working illumination is safe byperforming the Fogging Test.

Note: Any coating chemistry that spills on clothing and isilluminated by light will produce a stain that can only be removedwith a pair a scissors. Any coating chemistry that spills should not be used for important prints butshould be recycled if practicable.

Coating Components:

Sensitizer:This must be included as it makes the coating light sensitive. There are two major routes totake with the selection of the sensitizer. Ferric Oxalate (FO) provides what is called aDeveloping Out Process (DOP). Ammonium Ferric Oxalate (AFO) generally provides whatis called a Printing Out Process (POP). Each of these processes has its own characteristics.With DOP a developer is used; with POP the print goes straight into a water bath and thenclearing.

Note: Only use a sensitizer solution that is known to be good and of the highest quality.

FO DOP - allows for a variety of developers or enhancing agents.Provides for the best depth and substance.In general, FO requires less metal (solutions may be weaker) than AFO.

AFO POP - no developer may be required. However, use of Potassium Oxalatedeveloper will dramatically reduce contrast in the highlight values only.Provides more neutral color at higher relative humidity. Cool, bluish colormay be obtained with addition of some Pt double salt. A 60% solution ofAFO with the appropriate amount of metal can provide the best depth andsubstance of FO. In general, AFO must use more metal and higher strengthsolutions to achieve results comparable to FO.

Metal Solution:


7.5

The metals are what form the final image. The metal solutions are made from what aretermed double salts of the noble metals platinum (Pt) and palladium (Pd). These have theform X2MCl4 in which X represents a period I element (alkali metal) and M represents theNobel metal (Cl is the symbol for Chlorine).

Pt/Pd RATIOS:The following evaluates general relationships for the ratios of Platinum to Palladiumsolutions for DOP. The strengths of the individual solutions are determined by the sensitizerand can be found in the section on Optimization or calculated from the Metal SolutionFormula Calculator (requires JavaScript capable browser).

100% Platinum 80% Pt There is not much noticeable difference between 80% and 100% platinum. 50% Pt More Pt will discriminate sharper detail; produce cleaner whites; more

contrast; a colder, blacker image; exposes faster. More than 50% is rarelyused.

35% PtMaximum substance in image for most papers occurs at 25% to 35% Pt

25% PtGood ratio for fabric is from 10% to 30% Pt

10% PtWarmer, browner image; less contrast; exposes slower.

0% Pt 100% Pd gives slightly pinkish highlights, also will discriminate very highvalues. Can discriminate Zones IX, X, XI, and even XII. Palladium tendsto cling to the paper fibers better making clearing more difficult.

Note: The platinum solutions for both DOP and POP should be warmed, but kept below 140oF.

Double Salts of Palladium:Several Pd salts have been used and can produce various results. This arerepresented by X2PdCl4, where X is one of the alkali metals, lithium (Li), sodium(Na), or potassium (K).

Li Achieves the most neutral color with POP (high RH). Orangeish brown withDOP. Solutions stay dissolved at room temperature for both DOP and POP.Holds the most moisture in the coating.

Na Warm yellow, brown color with POP. Yellowish brown color with DOP. Namay react with the Pt salt at higher temperatures causing a precipitate.Solution for POP must be heated in water bath to keep dissolved.

K Slight warm color with POP. Warm deep brown color with DOP. Solutionsmust be heated in water bath to keep dissolved for both DOP and POP.


7.6

Contrast Agent:There are several agents that can be used to increase contrast either throughout the entiretonal range or within a local range. These agents can be part of the coating or can be usedin the subsequent processing as with those added to the developer. When used in thecoating, the are administered as a single drop of a certain percentage solution added to thecoating mixture. The contrast agent should always be the last ingredient added to the coatingmixture. Some unique effects may occur by mixing multiple contrast agents. A few agentsare discussed below. Some general tendencies are as follows.

* It is usually best to get the proper contrast in the negative. * Sometimes use of a contrast agent will prevent base fogging. * Less contrast agent may give more of a printout with DOP. * More contrast agent generally requires more exposure.

Potassium Chlorate -This is the traditional contrast agent. It tends to work mostly onthe upper tonevalues. Less gives a better quality print. However, sometimes some gives a betterquality print than none. ½% to 1% (and for some papers 2%) is the maximumamount for an 8x10 with most papers before image degradation is noticed. Toomuch Potassium Chlorate will hurt the paper, degrade the image, or add a lot ofgrain.

Hydrogen Peroxide -Hydrogen Peroxide wont degrade the paper or image like Potassium Chlorate.However, the larger concentrations of Hydrogen Peroxide may cause the platinumsalt solution to precipitate platinum or convert to K2PtCl6 (not very soluble in water).

Potassium Dichromate or Ammonium Dichromate -Higher concentrations do not seem to harm the paper like Potassium Chlorate.Potassium Dichromate may be added to the coating mixture (internal control) or tothe developer (external control), each producing some unique results. AmmoniumDichromate is thought to provide for a true contrast adjustment. AmmoniumDichromate provides for a more neutral color than other contrast agents for POP.

Na2PtCl6 -Richard Sullivan has provided some interesting information on the use of this Pt saltfor contrast control. His tests have shown it to provide true contrast control withoutdetrimental effects. (technical paper at this link) Dick Arentz also describes thiscontrast control in his latest book

Mixing the Coating:

The basic mixing rules are these:


7.7

Components are added in the following order: sensitizer, metals, contrast agents.Total amount of metallic salts is equal to the amount of sensitizer.There is only one drop of a contrast agent.

Procedure:

Set out a shot glass.Enter coating information in notebook (see notation below).Count out drops of sensitizer (FO, AFO) from a dropper (or use ml from a pipette).Calculate drops (or ml) of Pd and Pt solutions for the Pt/Pd ratio desired.Add drops (or ml) of Pd (Li, Na, K).Add drops (or ml) of Pt.Swish around to mix.Add one drop of ?% solution contrast agent.Swish around to mix and set aside for coating.

Note: It has been observed that for most POP and some DOP situations, results (apparent in theprint) are better when the contrast agent is added last.

Note: It is good practice to mix each coating solution immediately prior to coating. Some mixedcoating solutions have been observed to precipitate crystals if cooled or not used within 10minutes. Mixed coating solutions should not sit or be stored for more than an hour as themixture can "sour" resulting in a noticeable loss of print quality or inconsistent results.

Coverage:

Coverage determines the total amount of coating mixture to prepare for a print. The coverage of acoating varies by substrate, coating procedure and technique, and conditions and should bedetermined by experience and as explained in the section on Coating Coverage.

General Expectations:

Too much chemistry wastes $ and may cause blotchy areas.Too little chemistry will weaken the image.Papers with more absorbency will require more chemistry.Higher ambient temperature will require more chemistry on thicker papers.In general fabric will require three times the chemistry as an equivalent area on paper.Papers coat better when cooler (use a sonic mister rather than steam to humidify).


7.8

Keeping Notes - NOTATION:

Always record the paper and coating chemistry in the notebook.The following abbreviations can provide for quick and accurate notations.

General notation = [sensitizer]-[metal solutions]-[contrast agents]

sensitizer:#FO% = Ferric Oxalate#AFO% = Ammonium Ferric Oxalate

where# = amount in drops or ml% = solution strengthNote: If more than one source of FO is available, an additional letter candiscern the difference, such as VFO, JFO, BFO, etc.

Pd solution:#L = Li2PdCl4#N = Na2PdCl4#K = K2PdCl4

where# = amount in drops or mlNote: Solution strength is not needed as the solution strength of the metalsis determined by the solution strength and type of sensitizer.

Pt solution:# = K2PtCl4

or #Pwhere# = amount in drops or mlP = Pt salt (This is optional unless more than one Pt salt is used, thennotations can be used such as KP, NP, AP, etc.)Note: Solution strength is not needed as the solution strength of the metalsis determined by the solution strength of the sensitizer.

Note: Half strength solutions of metal solutions may be indicated by a /2 after the #.

contrast agents:%PC = Potassium Chlorate%PD = Potassium Dichromate%AD = Ammonium Dichromate%HP = Hydrogen Peroxide

where% = solution strength

For example, an 8x10 coating for Bienfang 360 paper may be expressed as: 12BFO27-9K-3-1/4PD


7.9

Coating Efficiency

ExplanationMeasurementCalculation

Coating Efficiencycreated August 1999, updated December 2000

Explanation of Coating Efficiency:Coating efficiency is the percentage of chemistry that goes from the coatingmixture into the paper. Losses are typically from brush absorption orclinging to the wall of the mixing/pouring vessel. Other losses can occurfrom mistakes and evaporation. Mistakes can be avoided by carefultechnique; the other losses are discussed further.

The brush can suck up a lot of the mixture. Pre-soaking the brush andsqueezing it out helps to prevent some absorption loss. When dealing witha relatively small amount of mixture this loss can significantly lower thecoating efficiency. Several drops could be held by a larger brush; a smaller brush for smallercoating areas is a good idea. It is recommended that the brush have a width of no more than 15%of the shortest side of the coating area (recommended brush sizes). A rod should have a much lowerloss than a brush, although some mixture does cling to the rod. A rod with a large diameter ortextured surface can contribute to a significant loss of coating solution.

Mixture also clings to the vessel from which it was mixed and poured. This amount becomessignificant for a small amount of coating mixture. One drop could easily cling, which would be 10%of a 10 drop solution. It is recommended that the brush be used to wipe any remaining mixture fromthe vessel.

Because of the variability of these losses with the amount of coating mixture, it is recommended thatcoating efficiency be measured for both small and large area coatings of sizes typically used.

Evaporation can contribute a variable and uncontrollable loss of water from the mixture. This doesnot cause a loss of active material in the coating, but it does play havoc with determining theefficiency. It is recommended that the weighing (discussed below in the Measurement Procedure)be conducted at lower temperatures, without any cross ventilation, and as quick as possible. For themeasurement of efficiency, single coatings are a must. Multiple coatings (with the quasi dryingbetween layers) loose too much of the water to provide a useful and consistent weight measurement.

Evaporation can be more pronounced in an ambient of low relative humidity. It is recommendedthat the coating efficiency be measured in ambient conditions of 50-70% RH with the paperstabilized at the ambient. A change in RH of the paper is easily detected by a changing weight.

Measurement of Coating Efficiency Measurement Procedure: All weights are measured with a scale capable of accurately measuring 0.01 grams.

� Select a paper of interest and cut to slightly larger than 100 square inch (about 654 cm2).� Delineate a 100 square inch area on the paper.


7.10

� Weigh the paper.� Weigh a shot glass.� Make up a typical coating mixture for an 8x10 area in the shot glass.� Weigh the shot glass with mixture.� Make sure scale is set to zero balance (ready to weigh paper).� Apply the coating by the well practiced and consistent technique to the paper within the

marked area of 100 square inches using the appropriate tool.� The coated paper is immediately weighed (no drying).

Calculation of Coating Efficiency

The initial weight of the chemistry mixture is:[weight of shot glass with mixture]-[weight of shot glass] = [weight of mixture]

It is assumed that the chemistry delivered to the paper is:[weight of post-coated paper]-[weight of pre-coated paper] = [weight of mixture coated]

The coating efficiency is calculated as follows:

[coating efficiency] = [weight of mixture coated] / [weight of mixture]


7.11

Definition of CoverageCoverage ExampleSome Coverage Values

Coating Coveragecreated August 1999, updated December 2000

The potential quality of a print is directly associated with uniformlyplacing a desired amount of metal into a desired area on a particularsubstrate. Accuracy and consistency of the coating technique is ofcritical importance. It is highly recommended that all coatingadhere to the following.

� Only Optimized solutions should be used. (See Chapter 6)� The coating must fully and accurately be kept within a

defined area.� Brushing or spreading technique must be practiced and consistent.� The coating efficiency should be known for each bushing or spreading technique, and

reevaluated if any change of bushing or spreading occurs.� The volume per drop must be known and consistent, if droppers are used to make the coating

mixture. The droppers must be of the same type and have the same drop size. Accuratepipettes may be used instead of droppers and will be more accurate.

� If one must error, a denser coating only wastes material, while a weak coating adverselyaffects quality.

Definition of Coverage:Coating Coverage is expressed as cm2/ml and defined as:

[Coverage] = [area of coating in cm2] * [coating efficiency] / [ml per drop] /[number of drops of sensitizer at specified solution concentration]

where,

[coating efficiency] is the percentage of chemistry that goes from the mixture into the paper.Refer to the section on Coating Efficiency for its description and measuring procedure.

[ml per drop] is calculated by counting the number of drops (#) it takes to fill a graduatedcylinder to 10 ml, then calculating (10/# = ml/drop) (This term is eliminated if pipettes areused and solution measurements are made in ml instead of drops.)

[number of drops of sensitizer at specified solution concentration] is determined by eitherof the following options:

A) experience and consistency of coating and performing the optimization study inVerification of Optimized Formulas, except finding the optimum number of drops(or volume) of the specified sensitizer solution for the given area (as opposed todetermining the solution strength). This is accomplished by varying the amount ofgiven coating mixture for a given area.


7.12

B) experience and consistency of coating as suggested in this Guide (Chapter 7), andusing the recommended value for a particular paper. This choice relies onmeasurements made by the author, whereas option A requires the performance of theoptimization study.

Note: If using pipettes, enter the amount in [ml of sensitizer at specified solution concentration]in place of [ml per drop] / [number of drops of sensitizer at specified solution concentration]

IMPORTANT: Because diluted mixtures may be made (perhaps for multiple coatings), the totalnumber of mixture drops (or volume) is not an accurate reference. The appropriate reference is thenumber of drops (or volume) of sensitizer solution of a given concentration, which is identical tothe number of drops of metal solution. The purpose of coating is to get a known amount of activechemicals evenly distributed throughout the coated area. Coverage must indicate that amount.

Coverage can vary by paper and should be determined for each paper. Knowing the Coverage willpermit the easy transition from one paper to another without the worry of insufficient chemistry.Coverage can also vary with coating size as a variation of the Coating Efficiency. Coverage shouldbe calculated for the sizes and the specific paper which are commonly used.

Coverage Example:An example to calculate drops needed using the Coverage:An 8x10 image with half inch boarders (100 inches2 or 645 cm2), using a dropper having 0.05ml/drop, on a paper with a Coverage of 829 cm2/ml and a coating efficiency of 0.90 (90%), thenumber of drops of sensitizer would be calculated as follows.

drops = [area coated] / [ml per drop] / [Coverage] * [efficiency] = 645 / 0.05 / 830 * 0.90 = 14

A coating mixture for this 8x10 would consist of 14 drops of sensitizer, 14 drops of the appropriatemetal solution(s), an optional drop of contrast agent, and any optional dilution water (as when QuasiMulti-Coating). The coating would be evenly spread onto an area of 645 cm2.

Some Coverage Values:The values below are for the purpose of demonstration. The Coverage of a coating may vary bycoating technique and should be determined as outlined above including determination of the coatingefficiency. Coating coverage may decrease at higher temperatures (especially greater than 75oF) forsome papers.


7.13

The following substrates have Coverage as measured by the author.

Substrate for an 8x10 for a 4x5

name type coating efficiency

Coverage(cm2/ml)

dropssensitizer

coating efficiency

Coverage(cm2/ml)

dropssensitizer

Bienfang 360 thin paper .92 76.5 24 .81 73.7 6

Crane'sParchment Cover

thick paper .92 65.5 28 .81 63.2 7

Sea Isle fabric fine fabric .85 28.3 60 .78 28.4 15

Note: These Coverage values are for the standard temperature of 25oC, higher temperatures mayrequire more solution depending on the substrate.

Note: An 8x10 image (roughly 8 ½ x 9 ½) with a 1/2 inch boarder on all sides has an area of 99.75square inches. A 4x5 image (roughly 3 3/4 x 4 3/4) with a 1/2 inch boarder on all sides hasan area of 27.31 square inches.


7.14

PreparationHumidifyingBrushingDrying DOPDrying POP

Coating Paper - step-by-step Procedureupdated May 2001

Coating can make or break the process. There is nothing mystical aboutcoating, but one must practice coating. Only after coating several hundredprints may this simple technique be mastered. Coating technique and ease willvary from paper to paper. It is strongly suggested that one begin with an easyto coat paper; learn to coat it well; then maybe try another paper. It is to beexpected that various papers will coat differently.

Preparation Steps:

� Ambient work area preparation differs for DOP and POP and is an important step forconsistency and quality. (See the Wet Dry Drying Study.)

� For DOP, the temperature should be kept below 70oF and the relative humidity (RH) below40%.

� For POP, the temperature should be kept below 70oF and the relative humidity (RH) between40% and 70%. Variations in the RH can change the color of the print, in genaral producinga warmer color with lower RH.

� Have brush soaking in a dedicated tray of H2O.

� Have coating mixture ready in shot glass.

� Have paper ready with the desired side up (see Raw Materials - Substrates - Paper).

� Mark on paper the area to be coated with pencil dots at corners. Or, if paper is thin, placeold negative of same size under the paper as a guide.

Note: After some practice one should be able to coat the correct size without guides.However, it is critical to restrict the coating to a given area.

� With brush well soaked in dedicated tray, remove it from the H2O and squeegee between aclean paper towel.

� Take most of the H2O out of the brush, but leave damp.

Note: This procedure is intended to keep the coating mixture from being sucked up into thebrush (dry brush) or from being diluted (wet brush).

Humidification Steps:

� Humidify the paper by holding and moving paper over a sonic mister so that the front is


7.15

humidified, then so the back is humidified, then so the front is humidified again.

Notes: Do not get the paper soggy.

Do not get water droplets on the paper.

Do let the paper become humidified so that it just loses the crispness felt or heardwhen bending.

Some thin papers may not require humidification.

Brushing Steps (illustrations below):

� Place paper onto the coating work area desired side up (use a pad of newsprint or plasticsheet to keep spills or overshoots off the table). (figure A)

� Pour the shot of coating mixture in a line well inside one edge of image area. (figure B)

� Get all of the mixture out of the shot glass, with brush if necessary.

� Run brush down the line of mixture and spread. (figure C)

� Brush mixture across the paper perpendicular to the line. (figure D)

Notes: The previous four steps should occur as rapidly as practical.

Hold the brush at an angle of about 30o to the paper and pull along gently, butswiftly.

� Brush mixture in direction 90o to last brush direction. (figure E)

� Brush mixture in direction 90o to last brush direction and opposite to the first brush direction.(figure F)

� Brush mixture in direction 90o to last brush direction and opposite to the second direction.

� Repeat brushing in all four directions once or twice depending on how fast the coatingmixture is soaking into the paper. (figure G)

Notes: Stop brushing immediately when some drag is felt. Brushing beyond this point canabrade the paper and show as a textured spot in the print.

Coating must be quick and gentile and cover the entire image area. If not quick themixture may be lost into the paper.


7.16

Make sure the mixture is brushed thickly over the entire area. When coating is thinthe image will be weak.

Don't waste the chemistry by brushing it out of the image area.

Do not let the mixture soak through the paper. This may hurt the uniformity.

Also, do not let the mixture puddle, as this will also hurt uniformity.

Surface brush marks in the coating should not matter as long as the coating is solid.

� Place brush and shot glass into H2O bath (dedicated tray).

Illustration of brushing coating mixture onto paper:

A B C D E F GCoating paper by brush: (A) everything ready; (B) pouring the solution; (C) initial spreading; (D)brushing across paper; (E) brushing at 90o; (F) brushing in next direction; (G) brushing in nextdirection on repeat.

Drying the Coating:

Drying methods differ for DOP and POP. Be sure that the ambient conditions of the work area arestabilized at the desired levels within parameters above.

Coated paper wet (left) and dry (right).


7.17

Drying steps for DOP:

� Let the coating air dry until the glossiness goes away.

Note: Paper may be lifted and turned to prevent puddling by gravitational distribution.

� Dry front with hair dryer at settings of high blow and low or medium heat.

Notes: It is desirable to use heat, but do not get coating too hot (more than 140oF may dodamage.)

Puddles dried will show the edge and be blotchy.

� After front is completely dry, turn over and dry the back, then dry front again.

Notes: Coating must be "bone dry" for exposing.

Coated paper might be stored for up to an hour. Dry once again immediately priorto exposing. Never store for longer than an hour. The coating will depreciate withtime; so, no matter how it is stored, it will go bad.

Do not let any liquid, or drops, or spray, or fingers touch the coating, because doingso will leave a mark in the print.

Drying steps for POP:

� Immediately dry with hair dryer at medium or high blow and NO HEAT.

Notes: DO NOT use heat as it is imperative that the coating and substrate obtain the relativehumidity of the ambient.

Be careful so as not to cause any puddling of the chemistry. There is no time to waituntil glossiness goes away as with DOP.

� Drying should take about three or four minutes. The goal is to get the paper and coating tothe ambient relative humidity.

Notes: If too much time elapses from end of coating, through drying, to exposure, adverseeffects may occur such as graininess.

To check when drying is complete, a finger may be lightly moved across the coating.When smooth and not sticky, the coating should be at the proper dryness.

Too much drying will result in a warmer color (color may be blotchy if the dryingis uneven).


7.18

Expose immediately; do not store.

Do not let any liquid, or drops, or spray, or moist fingers touch the coating, becausedoing so will leave a mark in the print.


7.19

PreparationBrushingDrying DOPDrying POP

Coating Fabric - step-by-step Procedure:updated December 2000

TIP: First learn to coat paper. Otherwise you will most likely get blotchyresults and can waste a lot of material.

Preparation Steps:

� Ambient work area preparation differs for DOP and POP and is animportant step for consistency and quality.

� For DOP, the temperature should be kept below 70oF and the relative humidity (RH) below40%, although higher RH does not seem to affect results.

� For POP, the temperature should be kept below 70oF and the relative humidity (RH) between40% and 70%.

� Have brush soaking in a tray of H2O.

� Have mixture ready in shot glass.

Note: Remember fabric will require about three times the chemistry of paper.

Brushing Steps:

� Place fabric on glass or plastic sheet with the desired side up (see Raw Materials - Substrates- Fabric).

� Mark on the fabric the area to be coated with pencil dots at corners.

� With brush well soaked, remove it from the water and squeegee hard between a clean papertowel.

� Take most of the water out of the brush; brush should be just damp, not wet.

Note: This procedure is intended to keep the chemistry from being sucked up into the brushor from being diluted.

� Dip brush into the shot glass of coating mixture.

� Brush back and forth and up and down over a small area of the delineated fabric.

Notes: Keep coated areas wet with mixture. Do NOT brush thinly and let sit.Work quickly. If an area dries, then marks may appear in the print.


7.20

Fabric is much more durable than paper. Brushing may be quite rough.

Be careful not to catch fabric and cause a fold or crease. The fabric will tend toexpand when wet. Slight pulling from the sides will keep it flat. However, do notfasten or stretch the fabric in place.

Occasionally run wet (with mixture) brush over all coated areas to keep wet.

� Re-dip the brush and coat another area adjacent to the one just coated.

� Repeat the last step until the entire area is coated.

� Run wet (with mixture) brush in long strokes over entire coated area in every direction. Thiswill force the mixture into the fabric. Also brush any air bubbles out to side.

� When fabric seems completely soaked, but before any areas have started to dry, lift the fabricoff of the glass or plastic sheet.

Notes: There will be many small puddles of coating mixture left on the glass or plasticsheet. Do not let the fabric touch any of these once it is lifted and begins to dry.

From this point on do not let any liquid, or drops, or spray, or fingers touch thecoating, because doing so will leave a mark in the print. Also, do not let the coatedfabric touch itself.

� Hang the fabric up on a line with clips or clothes pins.

� Clean and dry the glass or plastic sheet. Residual coating mixture should be recycled ifpracticable.

Drying the Coating:Drying methods differ for DOP and POP.

Drying steps for DOP:

� Dry the hanging, coated fabric with gentile blow and low to medium heat.

Note: A few clips to weight the bottom will keep the fabric from blowing around.

� When fabric is dry place it onto the clean and dry plastic or glass sheet.


7.21

� Dry further with the hair dryer at high blow and medium heat until "bone dry".

Notes: It may be a good idea to tape or hold the end of the fabric toward the hair dryer.

It is desirable to use heat, but do not get coating too hot (over 140oF may dodamage.)

Coating must be "bone dry" for exposing.

� Once the fabric is completely dry, it is ready for exposure.

� Load into the printing frame and go immediately to exposure. Do not store the coated fabric.

Drying steps for POP:

� Dry the hanging, coated fabric with gentile blow and NO heat.

Notes: A few clips to weight the bottom will keep the fabric from blowing around.

Coating must be at ambient relative humidity for exposing.

� Once the fabric is at the ambient relative humidity, it is ready for exposure.

� Load into the contact printing frame and go immediately to exposure. Do not store the coatedfabric.


7.22

Drying the Coatingcreated August 1999, updated December 2000

How the coating is dried can influence the print greatly. Also specific variations such as DOP andPOP require drying specific procedures for optimal results. Two general procedures have beendesigned for drying the coating. These have been termed "Wet" and "Dry".

"Wet" means that the relative humidity of the coating is at equilibrium with an ambient RH of 40%to 70% (typically about 65% RH). This drying method is typically used with the Printing OutProcess (POP). Drying is accomplished by blowing ambient air over the coating until just dry.Dryness may be checked by lightly rubbing a finger over the coating to check if smooth (not sticky).Over or uneven drying can produce blotchy areas of warmer color.

"Dry" means what has been traditionally termed "bone dry". The ambient RH is lowered to below40% and the print dried by blowing air with medium heat over the coating to dry as much aspracticable. The lower the ambient RH, the better. This drying method is typically used with theDeveloping Out Process (DOP). Not enough dryness may reduce the depth and richness of thedarkest values in the print.

Drying scenarios in-between these may also be used.


7.23

Quasi Multi-Coating Methodcreated August 1999, updated December 2000

This author has had mixed results from multiple coatings in the past. A thought was that some ofthe past difficulties were associated with drying the mixture and then re-coating. Coatings ofmixtures containing 50 % to 100 % additional mixture had been brushed into the same areas withoutproblems. So, it was supposed that additional mixture could be added to the coating before it driedcompletely. (Hence the term "Quasi".) Keeping the coating moist seems to be the key to successfulmulti-coatings.

Multi-coating is not required on fabric as the coating method for fabric completely saturates thefabric with a single coating.

The Quasi Multi-Coating Method step-by-step procedure is as follows:

� Calculate the amount of chemistry needed for the mixture from the area to be coated, theCoverage factor for the paper (which depends on the type of paper, sensitizer and metalselection, and coating efficiency), and drop size (if measuring by drops). If measuring bydrops, use this equation:

([# of drops] = [area coated cm2] / [Coverage cm2/ml] * [ml per drop])

Or if measuring by pipette use the following:

([ml] = [area coated cm2] / [Coverage cm2/ml])

� Dilute the coating mixture with H2O so as to have enough volume for the number of coatinglayers anticipated (usually this will be double the amount which can accommodate at leastthree pouring layers).

� Pour out an amount of mixture onto the paper as typical for a single coating (usually half ofthat mixed and diluted).

� Brush this into the area desired as if it were a single coating.

� Allow to dry to the point of loss of the gloss, but before near dryness of any portion (ratherdamp).

� Pour out some more of the mixture (about half of that remaining).

� Brush this into the area desired as if it were a single coating.


7.24

� Allow to dry to the point of loss of the gloss, but before near dryness of any portion (ratherdamp).

� Pour and brush the remaining mixture as if it were a single coating.

� Dry to desired dryness for the "Wet" (POP) or "Dry" (DOP) method.

Each pouring should be enough to completely coat a layer over the full area. Do not extend anymixture beyond the area. With this Quasi Multi-Coating Method, it is of the utmost importance thatthe coating be restricted to the correct area. Spreading the mixture too thin (past the area) will resultin a weakened coating which, if below the threshold, will produce a weakened print. Not spreadingthe mixture to fully to cover the area will result in a stronger (is places) but incomplete coating.

A coating mixture with five pouring layers (5 quasi coats) has been accomplished taking a littlemore than half an hour to coat and dry. This produced excellent prints, although additional texturecould be felt on the surface of the paper. Similar quality prints were achieved with only the threepouring layers suggested without any roughening of the paper�s surface texture.

Notes: Drying times are significantly lengthened with multiple coats.

If an initial pouring layer is allowed to get too dry, lighter blotchy areas may appear in thefinal print.


8.1

Chapter 8 - ExposureLoading The Contact Frameupdated 3/2005

Notice: It has been discovered that with the Printing Out Process (POP) at high relative humidity(RH), after several exposures in succession, the printing frame warms enough to affect the relativehumidity of the coating resulting in blotchy patches of warm color. In order to avoid this problemit is suggested that the printing frame be close to the ambient temperature. This may requireallowing the frame to cool after each four or five prints depending on the length of exposures(warming). Or several frames could be rotated in use.

IN GENERAL:� Set and stabilize ambient conditions and wait until the paper has stabilized at these

conditions.

FOR PAPER:� First, write on the paper (outside of the coated area) a unique code to identify the print.

Note: This code could consist of the unique negative number and notebook reference.

For DOP only:� Dry coating and paper to "bone dry" immediately prior to exposure.

Blow dry with warm heat front, then back, then front again until "bone dry". Note: The surface will dry before the inside of the paper giving a false sense of

dryness.

For POP only:� Check ambient conditions.

Note: POP coatings should be at ambient relative humidity (RH). The RH of thepaper is controlled by controlling the ambient RH.

� Place the emulsion side of the negative toward the coating; align negative with coating; andhold together.

For POP only:Note: If the coating is at very high humidity, a thin mylar sheet can be placed

between the coating and the negative so as to protect the negative. Negativescan be permanently damaged by a wet coating.

� Place the negative and coated paper onto the glass inside the contact printing frame with thenegative toward the glass.

� Place the vinyl and then the foam backing on top of the paper.� Insert the back of the printing frame.


8.2

� Engage the spring clips and press the back firmly in place.Notes: Good contact of film and coating is important.

With thinner papers, make sure that the paper does not crease or fold. If necessarythe paper can be held tight and taped in place. Turn over the frame and check to seethat alignment of negative and coating is good.

Coating is ready to expose.

Note: Either side (but only one) of the printing frame may be opened for inspection without loosingregistration.

FOR FABRIC:

� First, write on the fabric (outside of the coating area) a unique code to identify the print.Notes: This code should consist of the unique negative number and notebook reference.

To write on fabric: place some tape on the reverse side, write using a pencil, thenremove tape.

For DOP only:� Dry coating to "bone dry" immediately prior to exposure.

Blow dry with warm heat front, then back, then front again until "bone dry".

For POP only:� Check ambient conditions.

Note: POP coatings should be at ambient relative humidity (RH). The RH of thepaper is controlled by controlling the ambient RH.

� Place the negative onto the glass inside the contact printing frame with the emulsion sideaway from the glass.

� Place the Fabric over the negative with the coating toward the negative and align properly.Note: Position the weave of the fabric with the negative.

� Place the vinyl and then foam backing on top of the fabric.Note: Make sure that the fabric does not crease or fold or stretch.

� Insert the back of the printing frame.� Engage the spring clips and press the back firmly in place.� Turn over the frame and check to see that alignment of negative and coating is good.

Note: Good contact of film and coating is important.

Coating is ready to expose.Note: Back of printing frame may not be opened to check printout since registration will not be

maintained.


8.3

Direct sunlightIndirect sunlightArtificial UV light

Exposingupdated December 2000

Exposure may be accomplished by illumination with sunlight or anartificial Ultra Violet light source. Different illuminations can producea variety of results. The sharpest prints will be made by direct sunillumination. The softest prints will be made by shaded or diffuse illumination. Both shade andmost artificial illumination may not cast a hard shadow. This gives a soft transition when burningor dodging without even shaking the tools (The wire handles of dodging tools may not even shadowthe print). It is also thought that various spectrums of light may produce differing results.

Notes: Any humidity in a DOP coating during exposure could add graininess or diminish the blacksin the print.The printout should only be checked with safelight illumination.

Exposure has some other effects on the print. As exposure occurs, development takes place and thecoating "prints out" (forms an image). The darker areas will become quite dark and in turn blocklight form further exposing the coating ("self-masking"). This can allow much exposure to be givento the coating with out a loss of shadow detail (of course, the negative should be properly made, withplenty of detail in the shadow areas). This also causes the contrast of the print to change. Moreexposure will produce less contrast, and less exposure will produce more contrast. These effects canbe useful when fine tuning a print.

The importance of a negative of sufficient contrast should be understood from these effects. If anegative has insufficient contrast, more contrast agent is used; the printing time becomes longer; thecontrast is thus lessened; so more contrast agent is required. Eventually the printing time becomesvery lengthy, and print quality may diminish.

Exposure by Direct Sunlight:

� Cover printing frame and take outside.� Set on the printing stand.

Note: Stand should be aimed directly at the sun. A pencil or stick perpendicular to theframe face will have no shadow when the frame is aimed properly. Uncover and starttimer simultaneously.

� Do any burning or dodging that may be needed.� At end of exposure cover and take back to darkroom.� Record printing information in the notebook.� Check printout and add exposure (optional).


8.4

Exposure by Sunlight, but in Shade:

� Cover printing frame and take outside.� Set in the shade (no shadows). Make sure illumination is even (spatially and temporally).� Uncover and start timer simultaneously.� Do any burning or dodging that may be needed.� At end of exposure cover and take back to darkroom.� Record printing information in the notebook.� Check printout and add exposure (optional).

Exposure by an Artificial UV Source:

� Place printing frame under the UV source (OFF).� Set then start timer, which switches on and off the UV source.� Do any burning or dodging that may be needed.

Notes: It is important to wear eye and skin protection when using an UV source (see sectionon safety). Record printing information in the notebook.

� Check printout and add exposure (optional).


8.5

DOP printoutPOP printout

Printout Evaluationupdated December 2000

The action of light in the platinum palladium process actually develops thematerial, resulting in metals becoming deposited into the fibers of paper or fabric. The material issaid to "print out". The printout is an actual image directly related to the materials used, thephotographed image, the exposure, and the ambient conditions. Once one learns to interpret theprintout, exposures and the need to burn areas may be evaluated and corrected, but only by theaddition of more exposure.

Notes: The printout should only be checked with safelight illumination.Although a short view with a 100W incandescent lamp at 5 feet should be fine.

The printout on fabric may be studied, but no additional exposure should be given becauseregistration with the negative cannot be maintained.

The Pt/Pd process can be divided into two sub processes. A Developing Out Process (DOP) whichuses the sensitizer Ferric Oxalate produces a partial printout with the full image emerging afterdevelopment. A Printing Out Process (POP) which uses the sensitizer Ammonium Ferric Oxalateproduces a full printout which looks close to the final print.

DOP Printout:In evaluating the printout, it must be remembered that the printout will differ for various papers andchemicals. It is helpful to have part of the coating completely masked from exposure so that it maybe used as a reference. In general, not much can be seen of Zones VIII and above in the printout.The surplus coating around the negative receiving maximum exposure can be useful in judging thedarkest areas in the print.

Learning to evaluate the printout is like learning to read the densities in the negative and in the print(see Sensitometry section). Much experience is the only way to master this evaluation technique.With experience comes a feeling for what the print will look like and what will happen and if moreexposure is applied.

POP Printout:This printout is very useful in that it is very close to what the final print will look like. However,one must take into account that a layer of chemistry is also seen which will subsequently be clearedfrom the print.

Another factor is that since the printout is much more full, more self masking is achieved makingthe effects more pronounced than those of the DOP. This could result in a lower contrast or inlonger exposure times.


9.1

Chapter 9 - ProcessingDevelopingupdated December 2000 and March 2005

The platinum palladium material actually develops as it is exposed to light and the subsequentchemical bath serves to enhance this affect. This is observed as the printout. However, two formshave been described as follows. POP (printing out process) achieves a complete development duringthe exposure and does not require further development. DOP (develop out process) achieves apartial printout and requires additional chemical enhancement development. Whether the processis POP or DOP is primarily a function of the sensitizer and other coating materials used.

The most commonly used developer is Potassium Oxalate. Developers may be used at varioustemperatures or with certain additives to produce various outcomes in the final print.

Ammonium Citrate is another developer, although it tends to produce a flat look by itself. A moreneutral color (from this developer) can be achieved while maintaining the desirable qualities ofPotassium Oxalate by mixing it 50-50 with Potassium Oxalate. Once mixed these developers seemto separate and should be shaken or re-mixed immediately prior to use.

Procedure:

� Place print, image side up, into the dry development tray.� Pour developer bath over the print.

Notes: Pouring should be quick and even and completely cover the print.If a dry-wet line is formed, it is likely to show in the print.If the print is placed into a damp tray, the developer bath must be poured over theprint before any moisture can soak into and through the print. If moisture does soakthrough a light blotchy area is likely to show in the print.

� The image appears very quickly. But, let it sit a while (about a minute) with occasionalagitation.

� Lift by a corner and drain as much developer as practical.� Print is ready for the pre-clearing rinse clearing.

Notes & Considerations

Important: The developer should be replaced at some point rather than continuously replenished.This was determined by the Clearing Study which found that a heavily useddeveloper can cause fogging.

http://jeffreydmathias.com/guide/chapter15.pdf


9.2

Be careful not to bend the paper, especially the thinner papers. This may produce apermanent crease in the print.

The image on paper is extremely susceptible to scratching when wet. Therefore, do nottouch the image area and keep the print image side up in all trays.

Fabric is quite tough. The print will not be hurt by any physical action short of tearing it.Also, the print is very hard to scratch.

Disposal of Acid Developers

Spent acid developers should be poured into a large bucket containing some water and baking soda.Use enough backing soda to give a pH of 7. More water should then be added to dilute the waste.Neutralized and diluted waste can then be poured down the drain with more water.


9.3

Test for ClearingClearing Study

Clearing Recommendationsupdated 3/2005

Clearing removes all ferric and ferrous compounds and all metal salts leaving only metallic platinumor palladium imbedded in the substrate fibers. Clearing platinum palladium prints completely hasalways been a concern. The traditional methods of clearing were not complete. Some discoverieshave included:

� The traditional Hydrochloric acid bath may "bleach" the image (especially in the highlights)with most papers (especially the thicker ones requiring longer clearing times). Dick Arentzfirst addressed this by suggesting the use of Phosphoric acid clearing baths.

� A pre-clear water bath for 2 minutes will dramatically shorten clearing times (in most casesby about half). The author as well as several others independently discovered this pre-clearwater bath.

� A new indicator helps to determine if clearing is complete. This indicator was introducedby John Melanson. (see the Test for Clearing)

� The author�s Clearing Study of 2001 found that the addition of Oxalic Acid and EDTA(CAS: 60-00-4) to the Ferric Oxalate sensitizer can dramatically improve clearing of anyclearing agent.

General note:If the print dries at any time before clearing is complete, further clearing may not be successful.

Current Clearing Recommendations:

In all cases:Use a pre-clear water bath for 2 minutes.

When using Ferric Oxalate Sensitizer:add 0.04% to 0.1% EDTA (CAS: 60-00-4) and3% to 4% Oxalic Acidto the sensitizer solution.

Notes: The use of too much EDTA can result in a "bleeding" of metal during processing. The actualamount can vary with different papers, so the smallest amount of EDTA to add to thesensitizer to assist with clearing should be determined for each paper.


9.4

In general Ammonium Ferric Oxalate coatings will clear in about half the time of FerricOxalate coatings without the additives. No study has yet been performed with additives toAmmonium Ferric Oxalate.

All water should be filtered to 0.5 microns. Particles in the water can scratch the printsurface.

Continue to work in a safe light as the print will remain light sensitive until completelycleared.

Water high in iron may hinder the function of the clearing bath.

Following these recommendations almost any clearing agent can be used including water,although times may vary as per the Clearing Test. Refer to the sections on Chemicals andPreparing the Stock Solutions for various clearing Agents.

Clearing Procedure for all substrates using any clearing agent:

� [When the FO sensitizer is mixed] Add 0.4% EDTA (CAS: 60-00-4) and 3% Oxalic Acidto the sensitizer.

� [After development] Place print into a tray filled with tap water until most of the unusedcoating is dissolved (typically 2 minutes). If the print floats, place image side down makingsure there are no air bubbles on the print surface.

� Lift the print from the rinse and drain (allow most liquid to drain from substrate).� Place print into the first of three clearing baths.� After a third of the total clearing time with occasional agitation, lift the print from the bath

and drain. This is typically 3 to 5 minutes depending on the clearing agent used, the paperand the coating.

� Place the print into the second clearing bath for the second third of the clearing time.� Lift the print from the bath and drain.� Place the print into the third clearing bath for the final third of the clearing time.� Lift the print from the bath and drain.� Place the print into a tray of water for 5 minutes. (If acid clearing baths were used, some

baking soda may be added to help neutralize the acidity.)� Lift the print from the rinse and drain.� The print is then washed in fresh, filtered water for another 5 minutes.

Notes: Washing neutralizes and removes the clearing solutions and is considered part of theclearing process.

The third clearing bath and second wash must be fresh. When the third clearing bathshows slight coloration (in normal white room light), move it to be used as thesecond clearing bath. Move the second clearing bath to be used a the first. Properly


9.5

dispose (see below) the first clearing bath when it shows a strong amount ofcoloration.

At the end of the work session, the second and third clearing baths may be stored inbottles and used as the first and second (respectively) clearing baths for next worksession.

Thicker, stiffer papers or fabric may be placed in a print washer. This will actuallywash them better. But, make sure that there is no residual negative chemistry in thewasher or stains may result. Thin papers which might fold should be washed in atray.

The image on paper is much more susceptible to scratching when wet. Therefore,do not touch the image area and keep the print image side up unless working with apaper that floats on the surface (see next note.)

Some papers float. If this is the case, place face down or use a cover in the printwasher. If face down, check that no air bubbles are trapped on the paper surface.

Disposal of Acid Clearing Baths

Spent clearing baths should be poured into a large bucket with some baking soda. Use enoughbacking soda to give a pH of 7. Water should then be added to dilute the waste. Neutralized anddiluted waste can then be poured down the drain with more water.


9.6

Dryingundated 3/2005

Drying Procedure:

� Lift from wash water, drain, and� If a thin or fragile paper, place face up on a drying screen.� If a strong paper or fabric, Hang by clips on a line.

Notes: The thicker papers will dry much better if hung.

Be careful not to bend paper, especially the thinner papers. This may produce apermanent crease in the print.

Drying may be accelerated with blowing warm, dry air.


10.1

Chapter 10 - Optional ProcessingBrighteningupdated December 2000

An optical brightening agent may be added to the paper. This can have the effect of changing ayellowish natural paper color to a neutral white color. This can be a way to achieve a brightnesslacking in most papers.

What happens is that the brightening agent has the property that when subjected to UV light, it inturn reflects blue light. Even a tungsten bulb emits enough UV for the agent to function. However,it must be remembered that brightened prints can look different under different illuminations. It isimportant that the prints be evaluated in the same illumination in which they will be displayed.

To make a working solution:

� In tray pour 32 oz water (0.5 micron filtered tap water or distilled)� Add 15 ml Sprint Print Brightening Converter� Add 1 ml Kodak Photoflo� Mix well.

Note: The solution should be made fresh for each session and not stored.

Procedure to Brighten a print:

� After a print is fully washed or after a finished dry print is completely soaked in water,� Place print in tray of Brightening solution (above working solution).� Agitate gently for 1 to 3 minutes (depending on amount of brightening).� Dry

Note: If brightening is too intense or no longer desired, it may be washed out of the print.However, this may take ½ to 2 hours, and the paper may not hold up to this much morewashing.


11.1

Chapter 11 - FinishingSpotting

Spotting will add density to areas of the print. Prints may be spotted using a conventional spottingmaterial and a #7-0 to #10-0 red sable brush. A procedure follows:

� Mix spotting solutions to get desired color.� Spread onto a plastic or glass sheet and let dry.� Dampen brush and rub on dry spotting material.� Test shade on the same type of paper printed on.� If too dark, moisten brush a little more, rub on dry spotting material and test again.� Dab brush gently and accurately onto required area.

Notes: It is much better to have a lighter shade and build it up to match.

Too much shade might be washed out with water, but most likely it will remain evident inthe print as a blemish.

It is efficient to spot dark areas first and then lighter areas as material is used from brush.

If the brush is too wet, too much spotter will blotch over the print. This will also happenwhen the spotting solution is used directly from stock solution without drying it.

A magnifying lamp works well for this tedious procedure.

Sometimes the color of the spotting material might be different for light and dark areas.

Too much brush movement will abrade the paper and show in the print.

Too large of a brush will result in a doughnut like blotch, which most likely will remainvisible in the print.


11.2

Etching

Etching will reduce the density in areas of the print. Etching is basically limited in usefulness toremoving small dark specks from the print. The reason is that if a large area is etched it will showin the print as an abraded area.

To etch an area:

� Use a pointed razor knife blade.� VERY SOFTLY touch the blade to the speck.� Pick at the speck slowly taking caution not to break any of the paper fibers.

Note: Using a magnifier lamp is a must.

WhiteoutAs an alternative to etching (for small density changes), and for lightening larger areas, Whiteoutmay be used. A good quality translucent white pigment is recommended for this.

To whiteout an area:

� Spread white pigment onto a plastic or glass sheet and let dry.� Dampen brush and rub on dry pigment.� Test shade on the same type of paper printed on.� Dab brush gently and accurately onto required area.� Let dry.� Repeat above steps to lighten further if necessary

Notes: A magnifying lamp works well for this tedious procedure.

This procedure will only work for small changes to the density. Otherwise the area workedwill show in the print, especially when viewed from various angles.

Too much brush movement will abrade the paper and show in the print.


11.3

Matting

Platinum-palladium photographic prints are among the finest of all works on paper and should bemounted accordingly. The mat board should be of the highest quality museum board (100% cotton,acid free, and white in color)(buffering is OK). Two 4-ply mats should be used, hinged along oneedge (usually the top). One solid for the back and one with a cutout for the front. The cutout maycome to the edge of the image or (if a boarder was masked around the print) a margin of paper basemay be left between the image edge and the cutout. Prints should be held to the back mat withcorner mounts. This way the print may be removed and placed into another mat if necessary.

It is recommended that prints not be stored with a cover sheet between the top mat and print. Whenthis cover sheet is slid or removed, it may scratch the print by rubbing over it. Platinum-palladiumprints are very susceptible to scratching or burnishing of the paper. Therefor, any good prints shouldbe matted and stacked in an archival box for storage. There can be nothing worse than scratchinga finished masterpiece.

If a platinum-palladium print is to be exhibited without a cover glass (not recommended, but mayhappen), it may be afforded some protection be spraying it with a coating of archival acrylic fixative.It is suggested to use a reversible type. This coating will tend to repel moisture and scratches, butnot completely.

Mounting Fabric:

Fabric should be attached to the back mat board with a single piece an archival tape along the entiretop edge. This must be done carefully so as to not stretch or compress the fabric as it is being taped.

To sign or write on fabric, place a piece of removable tape on the reverse on the fabric where thewriting is to be done and then remove the tape after writing. The tape will provide a firmnessallowing the fabric to respond to a pencil such as a rough paper might.


12.1

General DescriptionEquipmentFilmProcessing ChemistryStep-by-Step Instructions for Positive Shadow Mask Negative Highlight MaskManipulations

Chapter 12 - Building Analog NegativesBuilding Negatives by the Analog Methodupdated August 2001

General DescriptionThe two general methods availiable for building negatives aredigital and analog. The Digital Method optically scans anoriginal into bits electronically stored on a computer,manipulates the data by software, and prints a negative withink on a transparent substrate using a printer. The digitalmethod is discussed in Chapter 13. The Analog Methodconsists of enlarging and exposing by optical means ontophotographic film and is the subject of this chapter.

The nature of the platinum/palladium print requires that a contact print be made. Thus the size ofthe print is restricted to being the same size as the negative. To make a larger print, a larger negativemust be made. As always, there are many ways that this can be accomplished. But, the techniquesdescribed here will give unsurpassed, excellent results. It is most important to consider that the builtnegative can alter and independently manipulate several tonal ranges producing a final negative thatwould be impossible to create with camera and film alone. These negative building techniques werelearned from Sal Lopes and used over many years. Finally, after years of building negatives, I madesome minor refinements.

The basic steps are:� Set up original negative in an enlarger.� Make a positive and a shadow mask.� Make a negative and a highlight mask.� Use the negative and highlight mask to make a print.

A general rule to remember is:NEVER take short-cuts.Materials like direct duping films that bypass the negative step will NOT give anywhere nearthe quality of the results of the process described here. Negative building is a timeconsuming process, but well worth the results.

This chapter will provide information on equipment and materials needed and detailed instructionson how to make the negative, shadow mask, positive, and highlight mask. Do NOT assume that onecan get results quickly or willy-nilly. One must make an effort to adhere to these directions. Thisis the only negative building process I learned from Sal Lopes and the only process I have used andcontinue to use. Only after many years of mastering this process have I suggested some smallrefinements.

Note: Do not attempt to build large negatives until original negative processing and the matrix


12.2

described at the beginning of this manual have been mastered. (A waste of time andmaterials can be the result.)

Enormous control is achieved through these four pieces of film. The relationship between the masksand the bases is quite interesting. The exposure will determine the range of image values to appearon the mask. These image values start at the darkest for the shadow mask and at the lightest for thehighlight mask. The range of values may extend as far as one desires. However it must beremembered that 2556 film it quite contrasty which means that it has a limited range of total valuedynamic range. If one wishes to produce mask of a large value range, they should consider anotherless contrasty film for the mask. [Note: Try to keep the mask film as thin as possible whilemaintaining dimensional stability.]

An interesting feature of the masks is that they will increase the discrimination of tonal values.When each mask increases value discrimination on the positive and the negative, an extremely sharpimage is formed. In fact a built 11x14 negative from a 4x5 can have more apparent sharpness thanan original 11x14. Incredible sharp images can even be produced from 35 mm originals. Thisoverall sharpness effect only works if both a positive and negative are made. Do keep in mindthough that a smaller original negative will have less information to work with. There is no way tocreate more original information.

A common need in platinum/palladium prints is enough detail in shadow areas. Because of the matsurface of most papers, detail is lost in the shadow areas. The contrast of the shadow mask can beincreased to overemphasize the shadow contrast in the negative resulting in a good normal contrastin the print shadows.

A trick Sal Lopes taught me years ago is that the grain in a image can be made to disappear. Whenmaking the shadow mask an embroidery hoop with a nylon stocking stretched across it is placed infront of the enlarger lens and jiggled during exposure. Then when the negative is made, a piece ofMylar is placed between the positive and the shadow mask. These actions offset the masks from thebases just enough so that any image resulting from the grain in the original is canceled anddisappears.

Burning and dodging of areas can be achieved which would normally be close to impossible and tootedious. For example: The image has a sky with many individual clouds in it and to furthercomplicate the situation tree branches are everywhere. The problem is that a couple of the cloudsin one portion of the print are too light and the contrast of the print is perfect and the sky andbranches are perfect. Simple burning would darken portions of the sky and the upper portions ofthe branches as well. The solution is to build a highlight mask which only includes the values of theclouds and higher. The sky and branches (darker tones) will be blank on the mask. The cloudswhich are too bright can have some density removed on the highlight mask with the PotassiumFerricyanide solution. In the final print all the clouds are consistent and the sky and branches arethe same. Remember that the density of the mask is added to the density of the base requiring largerchanges than one might first expect.


12.3

A general rule is that any hand work should be applied to only the masks, whereas exposure dodgingand burning may be done on any of the films. One should consider that if a general burn or dodgeis needed on a base, it will most likely also be needed on the mask.

There have been instances where multiple shadow or highlight masks are used. An image has sometrees with some very dark areas in which there are a lot of lines. If only a short exposure mask wasmade, the zone II and III would be lacking some needed contrast. If the proper exposure andcontrast necessary for the dark line were given, the zone II and III would look unnatural. So, aproper shadow mask is made to accommodate the zones II and III and a second shadow mask ismade with less exposure and high development to only add the line to the print. When using morethan one shadow mask the mask controlling the lowest values should be placed on the stack last (andfurthest from contact). And when using more than one highlight mask the mask controlling thehighest values should be placed on the stack last (and furthest from contact). These mask will befurther from the printing area and thus less focused, but because they are in the darkest or lightestareas of the image any loss of sharpness should not be as noticeable.

By this technique one may control many image characteristics.Some examples:� reduce the contrast in the mid Zones by lowering the contrast of the positives and

negatives� increase contrast in the dark or light zones by increasing the contrast of the shadow

or highlight masks� lose upper or lower end zones by increasing contrast of the positive and lowering

contrast of the negative. This can take zones II through VIII and make them looklike zones I through IX.

+++ GOOD LUCK +++

�Luck is a combination of skill and preparedness.�(Quote by Edward Weston from his daybooks.)


12.4

Equipment

The following equipment is required for building negatives as instructed in this guide:

� Enlarger with cold light� Good easel fixed so that will not move in relation to enlarger� Contact printing frame - the same one used for platinum printing will do� Opal glass or plastic sheet same size as printing frame� Dodging tools - these will be custom made as needed� Mylar sheets same size as film (See mask making)� Embroidery hoop and nylon stocking (See mask making)� Safe lights for film - 2� Timer for enlarger [see appendix for schematic of a light intensity monitoring device.]� Compensating developer timer from Zone VI Inc.� Large sink - 3 foot by 10 foot works well for up to a 16x20 film size.� Water filters on tap water.� Trays - Five trays work well.

For film sizes over 24 inches, a mechanical processor should be considered.For film sizes capable of handling, trays slightly larger then the film size will workbest.Note: NEVER use the same trays for platinum processing - stains will ruin prints.

� Print/negative washer which accommodates the size of film.� Graduated cylinders - 2, 100 ml with increments of 1 ml� Graduated measuring cup - 1, 500 ml with increments of 10 ml� Measuring cups - 2, 1 quart with increments of 1 ounce� Storage bottles - 2 (for stop bath and fixer)

Notes: Developer and hypo clearing bath should be made fresh each time.NEVER use these graduates, measuring cup, or bottles for platinum processing

� Towels to dry hands (separate from those used for platinum processing)� Paper towels

Note: Bounty brand paper towels (regular) do not leave lint and do not scratch.� Clips and line to hang negatives for drying� Wet light table - large enough to hold two or more of largest film-size pieces and

water-proof� Small plastic beakers - 3, for manipulation chemistry� Cotton balls and Q-tips� Several small sizes of sable brushes� Notebook


12.5

Film

In general the films used must be dimensionally stable because of the requirement for preciseregistration. The films should be as thin as possible. Also it is advantageous to use a film that canbe used with a safe light.

BASE FILM:

The best base film for building negatives should have a very long straight line density-log-exposurecurve and a very high silver content. These are the characteristics of Kodak Commercial Film 4127.No other film achievs the image quality that 4127 film provides. The problem with 4127 film is thatit is currently only easy to buy in 4x5 or 8x10 sizes, unless one purchases an entire run from Kodak.[This is a problem.]

There may be several substitutes for 4127 film. A possibility could be Kodak Duraclear material.It is processed by the Ra4 chemistry in a tray or mechanical processor. It is available in a varietyof sizes including some long roles. This film has not yet been tested.

MASK FILM:

An excellent film for the masks is Kodak Kodalith Film 2556.

It may be helpful to have the base film slightly larger than the masking film, although this will costextra. For example with 8x10 film, make the image size approximately 7x9 and trim the masks to7½x9½. This is because the image is easier to view on the light table with the mask on top of thebase. This is done when registering by taping together. Having the top piece of film smaller givesroom to tape together. Having the mask larger than the base can work, but not as easily. Havingthe mask and base the same size makes it difficult to tape the films together for registration.

Note: Unfortunately films are becoming less available as the graphic arts industry moves to digital.

One film that has promise, while it remains in production, is Kodak Duraclear.


12.6

Processing Chemistry

Function Chemical Mixing Time

develop Kodak HC-110 8, 16, 32, 64, 128, or512 ml per litter

3 - 6 min.

stop Kodak Indicator 12 to 15 ml per litter 30 sec.

fix Kodak Rapid Fixer 250 ml per litter(Part A only)

2 - 4 min. (4127)1 - 2 min. (2556)

rinse water tray 1 min.

hypo clearing Sprint or Hyco 1½ oz per quart 1 min.

wash water print/film washer 10 - 15 min.

wetting Kodak Photoflo 5ml per litter 30 sec.

mask manipulation:

lower density PotassiumFerricyanide

12 crystals per 30 ml 1 - 10 min.

increase density Selenium toner straight to 1:4 1 - 4 min.

Note: All mixing is with 0.05 um filtered tap water.


12.7

Building the Positive and Shadow Mask

� With the original negative in the enlarger, select a size which will leave at least a ½ to 1 inchwide boarder on the size of film used.

� Focus carefully on a piece of scrap 4127 film in the easel, then remove that film.

� TEST: [Note: The positive and shadow mask are tested in tandem.]� Make a guess at the exposure time and development concentration and time for each.� Expose a small piece of 4127 film cut from a piece of film from the same box as will

be used.� Expose a small piece of 2556 film at the same location.

Notes: 4127 film can vary widely from batch to batch.Choose part of the image that has both extreme light and dark values.When exposing, it is much more accurate to:

1) hold a card I front of the lense;2) turn on the enlarger;3) remove the card and start the timer simultaneously;4) when time is up, replace the card;5) turn off the enlarger.Note: Instead of a timer, metronome tics can be counted from a

device that varies the time between tics directly as a functionof the intensity of the lamp intensity. A schematic for such adevice is found in this guide labeled �light intensity monitor�.

� Develop films at their respective concentration and time.� Stop� Fix� Rinse� Evaluate on light table� Repeat these TEST steps until the positive and shadow mask look right when

registered.Note: The positive and shadow mask should look pretty much like the print except

that the dark values will be blacker in the print. When done properly, theimage will have a �glow� to it. A matrix could be made for this process; butthere are so many variables, such a matrix may not be practical. Afterseveral hundred built negatives, one should begin to understand therelationships between the finished print and the positive, negative, and masks

� Enter date, image size, f-stop, exposure time, developer concentration and time into thenotebook for each.

IMPORTANT: Once the enlarger is set up do NOT move anything, do NOT focus, do NOTchange f-stop, do NOT move easel, do NOT bump enlarger.BE CAREFUL!


12.8

MAKING THE POSITIVE:� Expose a sheet of 4127 film for the exposure time� Develop at the concentration and time� Stop 30 sec.� Fix 2 - 4 min.� Rinse 1 min.� Hypo clear 1 min.� Wash 10 min.� Wet 30 sec.� Dry

MAKING THE SHADOW MASK:� Expose a sheet of 2556 film for the exposure time� Develop at the concentration and time� Stop 20 sec.� Fix 1 - 2 min.� Rinse 1 min.� Hypo clear 1 min.� Rinse 1 min.� Place on light table emulsion side up and blot with paper towel.� Using a cotton ball, spread Potassium Ferricyanide solution over the mask for 30 sec. to 2

min..� Using a paper towel, blot up the solution.� Using a cotton ball, spread fixer over the mask.� Lift the mask by a corner and drain.� Place into fixer for 15 sec.� Rinse 1 min.� Hypo clear 1 min.� If any density adjustments are needed, do them at this time. [see section on manipulations]� Wash 10 min.� Wet 30 sec.� Dry

Note: After rinsing, the positive and shadow mask may be viewed in registration to check if fineadjustments are needed such as dodging, burning, increasing or decreasing local densities.

Note: Film can be saved by making a RC print to first check for dodging and burning. Also filmprocessing can be calibrated using RC paper thus saving film. One must establish therelationship between the two materials. If one has mastered the normalization techniqueused with the Matrix, this will be quite simple.


12.9

Building the Negative and Highlight Mask

� Fasten the positive and shadow mask together with tape in registration and place into acontact printing frame.

� TEST: [Note: The negative and highlight mask are tested in tandem.]� Make a guess at the exposure time and development concentration and time for each.� Expose a small piece of 4127 film cut from a piece of film from the same box as will

be used.� Expose a small piece of 2556 film at the same location.

Notes: 4127 film can vary widely from batch to batch.Choose the same part of the image that was used for the positive test.

With a contact printing frame, exposure is made with the opal glass or plasticsheet covering the printing frame under the enlarger with the originalnegative removed and even illumination covering all of the contact printer.

� Develop films at their respective concentration and time.� stop� fix� rinse� evaluate on light table� Repeat these TEST steps until the negative looks right when registered with the

highlight mask.Note: The negative and highlight mask registered together should look like a

negative would for the Pt/Pd process. Keep in mind that this is a wetnegative on a light table. It might be helpful to compare values with thenormal negative from the matrix study also wet and on the light table.

� Enter date, image size, f-stop, exposure time, developer concentration and time into thenotebook for each.

MAKING THE NEGATIVE:

� Expose a sheet of 4127 film for the exposure time� Develop at the concentration and time� Stop 30 sec.� Fix 2 - 4 min.� Rinse 1 min.� Hypo clear 1 min.� Wash 10 min.� Wet 30 sec.� Dry


12.10

MAKING THE HIGHLIGHT MASK:

� Expose a sheet of 2556 film for the exposure time� Develop at the concentration and time� Stop 20 sec.� Fix 1 - 2 min.� Rinse 1 min.� Hypo clear 1 min.� Wash 10 min.� Wet 30 sec.� Dry

After rinsing the negative and highlight mask may be viewed in registration to check if fineadjustments are needed such as dodging, burning, increasing or decreasing densities locally.

Note: Film can be saved by making a RC print to check for dodging and burning. Also filmprocessing can be calibrated using RC paper thus saving film. One must establish therelation ship between the two materials. If on has mastered the normalization technique usewith the matrix, this will be quite simple.


12.11

Manipulations

There�s a lot to add here, but not yet written. Please see the General Description section.

It may be that future manipulations as well as enlargements are accomplished digitally. DanBurkholder and Dave Fokos both have written excellent material on digital negative building. Theauthor has researched the building of digital negatives. Two of the greatest challenges are thescanning of enough information from the originals and the equipment or service bureau to producethe final negative.


13.1

IntroductionConsiderations Resolution Ink Density Registration Posterization Calibration Boundary ConditionsMethods Stack Details of Stack Method MultipleComparison of Methods

Chapter 13 - Building Digital NegativesBuilding Digital Negatives for the Pt/Pd Processcreated April 2001, updated 3/2005

Introduction:The nature of the platinum/palladium process requires that acontact print be made. Thus the size of the print is restricted tobeing the same size as the negative. To make a larger print, alarger negative must be made. As always, there are many waysthat this can be accomplished. The methods described here arepreliminary but are expected to met the rigorous criteria for anegative suitable for the Pt/Pd process once ink on transparentsubstrate contains enough bit depth to render the tonal qualityneeded.

The two general methods available for building negatives are digital and analog. The AnalogMethod consists of enlarging and exposing by optical means onto photographic film and is thesubject of Chapter 12. The Digital Method involves optically scanning an original into data bitselectronically stored by a computer, manipulating the data by software, and printing a negative withink on a transparent substrate using a printer. The digital method is discussed in this chapter.

There are several approaches to making a digital negative and many factors are involved with thebuilding of a digital negative. A decision was made to utilize readily available equipment designedfor the home office that could get the job done and avoid depending on services from others. Thetwo methods described below have merit but have fallen short of producing negatives suitable forthe Pt/Pd process. The primary deficiency is with producing enough tones so as to avoid noticeableposterization and capture the tonal ability of the Pt/Pd process. This is directly related to havingenough bit depth represented in the inks printed on the transparent substrate.

These methods require the evaluation of Pt/Pd prints to calibrate and determine adjustments; onemust already be proficient with the Pt/Pd process.

Considerations:Resolution: Resolution of the scanner and the printer must be able to provide the minimum of

detail printable on the selected paper (see Resolution Appendix). A rough surfacepaper can allow for a lower resolution, while a smooth paper may require aresolution greater than available. A diffuse light source and a rougher paper mayhide the loss of resolution when contact printing. If more detail is desired from adetailed negative, the sun can be utilized as the light source and a smooth paper canbe selected.

Ink Density: Ink Density of the digital negatives must be great enough to allow a maximum white


13.2

in the print while producing a maximum black. This is a major consideration sincemost printers will not deposit enough ink at the resolution desired and most inks arenot opaque enough with the spectrum of light used to expose the Pt/Pd coating. Thismay be resolved by building a stack of several negatives (as with the Stack Method)or by using ink or multiple inks that can achieve the necessary opaqueness.

Registration: Registration is important and is related to the particular method of negative building.When several exposures are given to a single coating from several negatives, eachnegative must be accurately registered with the coating. This can be accomplishedby aligning two adjacent sides of the negatives and the print substrate.

When several negatives are to be stacked together, they can have registration marksadded to facilitate alignment.

Registration details can be found in the Registration Appendix.

Posterization: Posterization is the clumping of closely related continuos tones into discrete steps.All tones can be considered posterized to some level. What is important is thethreshold level of posterization at which the eye can discern a difference. Below thisthreshold the tones appear continuous. Above this threshold steps may becomedetectable, fine texture or subtle variances of tonality may be lost, or a sterile un-photographic look may result.

There must be a sufficient number of individual tones usefully spread throughout theprintable range of the negative so as to avoid noticeable posterization. At this time,it is not known how many tones are necessary or what the distribution should be.The number of tones per Zone (density ranges of the Zone System) likely varies aswell with a greater number of tones required in the mid Zones.

An increased number of tones can be achieved when several negatives from severalscans are stacked or individually exposed onto the Pt/Pd coating. However, 16-bitdata scanned, manipulated, stored, and printed seems the best solution. This canprovide 14-bit real data with 2-bits of noise separation.

Currently scanners are available that provide 16-bit data. Some 16-bit softwareexists and some trends seem to be moving in this direction. However, reasonablypriced printers have yet to come close.

Calibration: Calibration address several concerns and is a vital and useful part of buildingnegatives. All calibrations are evaluated using Pt/Pd prints. The negative buildingparameters set by calibration may vary with the original negative, Pt/Pd printingparameters, and desired results. The calibrations are performed in the followingorder.


13.3

Color Mix Calibration selects colors and inks and their mixture to determine thecontrol of the tones and keep colors within gamut of the printer and ink combination.

Maximum Black Calibration has two parts. Part 1 is dependent on the negativesubstrate and the total exposure given (Total Printing Exposure). Part 2 involves theminimum amount of ink to produce a discernible threshold above Maximum Black,is termed the Maximum Black Threshold, and occurs after the Maximum WhiteCalibration.

Maximum White Calibration determines the maximum amount of ink (subtractive)and/or the minimum exposure (additive) that must be controlled so as to provide thelowest print density. With multiple exposures, this may require an adjustment to theTotal Printing Exposure producing an Adjusted Total Printing Exposure.

Maximum Black Threshold (see Maximum Black Calibration above)

Base Curve Calibration produces a set of standard curves to be applied to everynegative set. One purpose is to adjust the Maximum Black Threshold without losingthe Maximum Black and provide the desired shadow detail. Another is to normalizethe distribution of data throughout the full range so as to produce the tones (bothvalues and amounts), local contrasts, and range desired in the print for a typicaloriginal. It is important to distinguish Base Curve Calibration from Creative Control.It is likely that every image will require tweaking (Creative Control) to arrive at adesired result. The first draft should have a standard applied (Base CurveCalibration) so as to provide for a starting point having minimum influence of theequipment and materials used to get from the original negative to the negativesproducing the Pt/Pd print. Base Curve Calibration can be thought of as the tuningof a piano.

Boundary Conditions:Boundary Conditions characterize the limits of a particular function and provideinsight as to the control of that function. Several follow which are useful withbuilding digital negatives and on which the calibration procedures are based.

Resolution - The resolution of the final print should be limited by the substrate used.The scanner, software, and printer should have resolution capability at or better thanthe substrate offers. A lack of resolution may not be apparent as a loss of detail inthe final print without magnification, however it is likely that the lack of resolutionwill be apparent as a lessening of texture, tactile quality, and tonal discrimination.The resolution must be actual physical resolution of the devices and not interpolated.

Selection of Ink (and/or printer) - It would be most desirable to have a multi-shadeUV/blue light blocking ink with high resolution print head.


13.4

Maximum White - Enough density of ink must be built up in the digital negative(s)so as to produce a complete absence of print density (paper white). Too little inkwill result in an inability to obtain a pure white in the print while maintaining theMaximum Black. Too much ink will result in a merger of the upper values into purewhite and a reduction of the total number of independent tones. (Too much ink mayalso cause puddling and a loss of resolution or fine discrimination of detail; seePuddling Appendix.)

Printing Exposure (Maximum Black) - Enough exposure must be given to the Pt/Pdprint so as to achieve a Maximum Black with a given negative substrate (includesbase plus fog). Too little exposure will result in a Maximum Black which isnoticeably too light and an image which may be muddy, have a loss of range, lackdetail in the dark values, or be without a black anchor to reference other dark values.Too much exposure will result in the dark values merging into the Maximum Blackand a lowering of all values, and the contrast of the Pt/Pd print may also be reduced,but with the sacrifice of lower density negative information.

Maximum Black Threshold - There is a certain density (ink amount) which willprovide a shade of black in the print which is noticeably lighter than maximum black.This value is a function of personal preference as well as the discrimination providedby the materials used. Too low of a threshold (lower ink amount) will cause thelower values to merge into Maximum Black. Too high of a threshold (higher inkamount) will cause less range of ink density and a reduction in the total number ofindependent tones.

Number of Tones (Posterization) - There are a certain number of tones in the totalrange and in specific sub-ranges (Zones) of the final print which are required toavoid detecting posterization. The number of tones produced in the print are afunction of the number of tones in the digital negative minus those below theMaximum Black Threshold, assuming correct Printing Exposure and MaximumWhite Calibration. Too few tones will result in noticable posterization. Too manytones will result in excessive information to be stored and handled. The number oftones can dramatically be restricted by the scanner, software, and printer. If theequipment has shortcomings, procedures might be able to overcome them. TheNumber of Tones may also be lessened by any software operations including, but notlimited to, curve adjustment and sharpening.

Methods:Two methods described have been fully developed and carried out, however only a summary isgiven as neither method has produced prints of acceptable quality. The primary deficiency is toogreat a level of posterization. Each method has significant merits and could be useful with theproper reduction of posterization. A complete description of the Stack Method has been added.


13.5

Stack Method:This method produces three negatives separating the low-mid, high, and upper densities of theoriginal which are then stacked together and exposed as a single negative to the Pt/Pd coating. TheStack Method, in effect, produces a single density from which to expose a Pt/Pd coating.

Each range of density is scanned from the original negative, the data manipulted, and each printed.Then the printed negatives are registered and fastened together and used as if they were onenegative.

Multiple or Tri-Negative Method:This method produces three negatives emphasizing the low, medium, and high density ranges of theoriginal which are then exposed one at a time onto the Pt/Pd coating. The Tri-negative Methodproduces three full range negatives which emphasize the low, mid, and high ranges of the originaland then exposes them onto a single Pt/Pd coating one at a time.

Three scans with various gamma adjustment are made from the original negative, the datamanipulated, and each printed. Then the printed negatives are used one at a time, in registration,to expose the Pt/Pd coating.

Comparison of Methods for producing Digital Negatives Topic Stack Method Tri-Negative Method

Equipment same same

Original negative same (optimized for scanner) same (optimized for scanner)

Scanning separate density ranges full range with different gammavalues

Normalization and/orcurve adjustment toaugment scan

Normalization done withscanner exposureadjustment, curveadjustment not necessary

May be needed if the gamma valuecannot select the desired emphasis(some scanners may have thiscapability)

Calibration effort straight forward complicated due to interrelationshipof negatives

Ink & Color Mixing straight forward straight forward (values may differfrom the stack method as more ink isused); However, the ink may notprovide enough density for one of thesingle negatives.


13.6

Total PrintingExposure (Maximum Black)

determined using three films,stacked together

determined using one film and willlikely require adjustment maximum ink amount

(Maximum White) easily achieved as theamount is divided amongstthree films

difficult to achieve enough ink toproduce the Maximum White (for atleast one of the negatives) as themaximum amount must be applied toeach film (the inks and printerselected can influence this)

Maximum BlackThreshold

easily achieved with curvesadjusting ink levels on thebase tone negative

easily achieved with curves adjustingthe sum of ink levels on all threenegatives

Standard Curves straight forward trial anderror

curves and exposure times must beadjusted together (intuition andfamiliarity may help with roughcalibration and fine tuning is tedious)

digital substraterestrictions

thin none

print substraterestrictions

none rigid so as to keep registration

registration operations once to index image; once to assemble stack

once to index two adjacent edges,then each time an exposure is made

contact when printing some physical distance ofthe negatives may cause areduction in sharpness whenusing lamps, but may becorrected by using sun

good contact, registration must beaccurate

printing exposures one (same as exposure togive Maximum Black)

three, interrelated (each asdetermined by calibration andcreative manipulation)


13.7

Procedure Original Negative Scanning Software Manipulation Normalization Color Mixing Curve Adjustment Printing Preparation & Output Making the Pt/Pd Print

Calibration Procedure Color Mix Maximum Black & Printing Exposure Maximum White Maximum Black Threshold Base Curve Calibration

Stack Methodcreated August 2000, updated April 2001

Note: This method is presented so as todemonstrate the procedure used. Much ofthis method related to the particularequipment may require modification. It isexpected that the entire portion involvingColor Mixing and ink selection willradically change with the use of proper inks,software, and printer. Although much of theother calibration procedure are expected toremain.

PROCEDURE to Build a Digital Negative by the Stack Method:This method produces three negative elements (a low to mid tone range Base Negative, a high tonerange High Negative, and a upper tone range Upper Negative) which are stacked together andprinted as a single negative. Three scans are made, one for each tone range, and three digitalnegatives are printed and used with one exposure to the Pt/Pd coating.

The resulting prints from this method have failed to be of acceptable quality due to:posterization - likely restricted by printer, driver, and inks and perhaps 8-bit softwarelack of detail - likely restricted by printer, driver, and the physical stack exposed using

UV lampslack of texture - likely restricted by posterization and lack of detail

However, it is felt that this method can succeed with proper printer, inks, and software.

ORIGINAL NEGATIVE:It is imperative that the original negative be optimized forthe scanner used. Basically the negative should have thegreatest dynamic range of densities and the maximumdensity should permit a scan signal uninfluenced by noise.Click here for a study of scanner noise and optimizingnegatives. A typical negative for use with the Pt/Pd processwill likely require a 16-bit scanner, assuming 2-bits arerelegated to noise suppression and 14-bits are accurate data.If less bits are available, then the negative must be processedwith less of a total range.

Figure 1: Full scan of an original negative.


13.8

SCANNING:Scanning reads the information contained in the original negative and places it into a digital datafile. It is important to scan in full color with the color saturation set to zero, at maximum pixeldepth, with the selected exposure range (see below), and at a resolution suitable for the final printsize (see Resolution Appendix). Sharpening should be set to none.

� Position original negative on the scanner as for a transparency scan, tape to glass, and maskall area except negative with opaque material.

� Perform preliminary scan.

� Set the Exposure Adjustment, Input Levels for one of the three scans:

1023 to 4095 for the Base Negative255 to 1023 for the High Negative0 to 255 for the Upper Negative

Notes: Setting the levels should normalize the data as described below in Normalization.Normalization equates the range of the original negative and the scanner.

The division between Base and High Negative (1023 value) may be altered duringcreative manipulation.

The upper range may be set at values larger than 0, if the dynamic range andmaximum density of the original negative is lower than the capability of the scanner,but keep the range width of 256.

The base range may be set at values lower than 4095, if the dynamic range of thenegative is lower than the capability of the scanner or in situations of much base plusfog.

If data is eventually converted to 8-bit (as with Photoshop V and most printers), keepany additions or subtractions of the range values to multiples of 16. The will helpavoid some round-off errors.

Carefully selecting the exposure adjustments can normalize the data here instead ofin the software (see Normalization below).

� Negative is scanned (using the settings above and in Equipment Setup) by the scanner standalone software and saved as a tiff file (include some film edge and some opaque area whendoing calibrations). Stand alone operation will better assure that the scanner settings remainconstant and each scan mechanically proceeds from and over the same position. Include aboarder for easier registration (see Registration Appendix).


13.9

� Save as a tiff file.

� Perform the other two scans changing only the Exposure Adjustment, Input Levels.

Figure 2: Base 1023-4095 (left), High 255-1023 (center), and Upper 0-255 (right)Negatives as scanned.

Figure 3: Prints from original sister negative (left) and digital negatives with base/high split of1023 (center) and base/high split of 1278 (right).

Note lesser local contrast in the high values (Zones V to VIII) of the print at rightcompared with the center print. Note that in the prints from digital negatives (center& right), the upper negative provides more local contrast than the original sister. Inall of the actual prints there is better shadow detail, but even more in the prints usingdigital negatives (not seen reproduced). Note that the original sister negative is anegative made for Pt/Pd printing while the original negative is of lower contrastbeing optimized for the scanner. Note also that the prints from digital negativesshow posterization, and a loss of detail (branches in lower right) and texture (largemetal areas). Because the sister negative was exposed at different moment, thelighting has moved.


13.10

Software Manipulation: (for each of the three negatives):

� Open file

� Change Mode to 16-bit Note: 16-bit mode will avoid round off errors causing a loss of data when changing modes

or applying calculations.

� Change Mode to CMYK Note: The proper CMYK color setting (GCR Maximum) should place all the data in the K

channel.


13.11

Normalization (optional):This step is optional at this position and should have been performed during the scanning (Settingthe Exposure Adjustment, Input Levels). Normalization equates the range of the original negativeand the scanner. Normalization selects the maximum black and white points of the print whileselecting a range of values contained in the original negative. The end points and range selectedmay differ from the range of the negative. End points selected beyond the range of the negative willresult in maximum tonal values in the print which are gray. End points selected within the rangeof the negative will result in a print with values from black to white but will include only theselected portion of the negative. (NOTE: It is important to select the exact limits of printable whiteand black. This is an important part of this procedure which likely differs from other methods.)

This step should be used to fine tune exposure which has been properly scanned. Most films willproduce densities exceeding the requirement of Pt/Pd coatings so over exposure can be correctedwithout a loss of total tonal range in the print. However, underexposure may result in anunrecoverable loss of information from the shadows. To adjust for over exposure use the whitepoint dropper to select a value in the negative to be set to the limit of maximum black in the print.

Selecting the unexposed film edge with the white point dropper automatically compensates for anyfilm base plus fog.

Alteration of contrast (overall or local) should be accomplished by the use of curves or layers later.

To reduce the overall tonal range in the print (end points selected beyond the range of the originalnegative), it is suggested that new calibrations be used instead. This will help keep the number ofindividual tones maximized and provide for better tonal discrimination in the print. Note thatnormalization may also be performed with the scanner and may provide better data. Normalizationwill allow for a standard set of calibration and curves to be applied to produce a consistent standardprint with a standard range of values ready for any desired optional creative control.

� Image, Adjust, Levels - set white point dropper to 0%C, 0%M, 0%Y, 0%K and set blackpoint dropper to 0%C, 0%M, 0%Y, 100%K.

� Use the white point dropper to select the lowest negative density which should represent themaximum printable black (film edge or as desired and may be used to alter the originalexposure).

� Use the black point dropper to select the highest negative density which should representpure white or paper base in the print (opaque area or as desired and may be used to adjustthe range of values).

� Apply the levels after optionally saving the level information. It is likely that each originalwill require unique levels.


13.12

Color Mixing:Color Mixing is a simple but important step that selects the inks to be used. It is very important thatcolors are selected so that the entire range of values/colors will be within gamut of the printer. Ifnot within gamut, the color may be arbitrarily changed or assigned the same value as another. (SeeCalibration Procedure.)

� Image, Adjust, Channel Mixer� Load the saved Mixer data.� Apply� SAVE as a psd file. This file is a backup of the unmanipulated data.

Figure 4: Base (left), High (center), and Upper (right) Negatives after Color Mixing.


13.13

Standard Curve Adjustment:Curve adjustment performs several tasks. For the Base Negative, it provides a steep ramp to bringink densities to a level which provide discernible tones while maintaining a Maximum Black. Forall negatives, it provides for contrast control and local creative control. A separate standard curveshould be applied first producing a standard print from which creative control may depart.

� Image, Adjust, Curves

� Load the appropriate standard curve.

� Base Curve as determined by the Base Curve Calibration. This should provide the lowervalues (about Zone 0 through Zone V) for a full range print.

� Curve for the High Negative (may be omitted).In Cyan and Black channels, change all output to 0.In CMYK and Magenta and Yellow channels, leave as straight 1:1 line.This should provide the high values (about Zone VI to Zone VIII) for a full rangeprint.

� Curve for the Upper Negative.In CMYK, leave as straight 1:1 line.In Cyan and Black channels, change all output to 0.In Magenta and Yellow channels, enter the curve formed when a point is added forinput=80 output=93.This should provide the upper values (Zone VIII to Zone XII and beyond) for a fullrange print.

� Apply the curve.Note: The standard curves should be used for every corresponding negative. For each

original an additional curve may be added specific to that particular image.

� Image, Adjust, Curves

� Make any creative modifications, adjustments, or refinements, save this curve informationseparately, then apply the curve. The step may be repeated after a print is made. This is thereason for saving the curve information.


13.14

Figure 5: Base (left), High (center), and Upper (right) Negatives after standard curves areapplied.

CLICK HERE to compare figures 4 and 5 (before and after the standard curves are applied).

Optional Creative Control:This is the best place for creative control with other 16-bit tools.

� Save file first.

http://jeffreydmathias.com/guide/before_after_curves.htm


13.15

Printing Preparation & Output:� Change Mode to RGB� Change Mode to 8-bit� Optional Creative Control: Save file first.� Sharpen with the unsharp mask.

Note: How to do this can be found from many sources. Sharpening is highly likely tofurther posterize the image, reducing the number of tones. Be cautious to keepsharpening to a minimum (see Sharpening Appendix).

� SAVE the final file.� Print on substrate with the settings determined by calibration.

Pt/Pd Printing:The resulting negative is assembled and printed with the materials and technique used for calibrationand the exposure determined during calibration.

� Position the negatives on a light table and tape together in the following order.� With ink side down, place Base Negative on light table,� register the High Negative to the Base Negative and tape,� register the Upper Negative to the others and tape,� use the stack of three as a single negative.� Print with the settings indicated above and from calibration. Note: For best resolution use a collimated light source such as the sun. With a diffuse light

source (such as a bank of BL bulbs), papers with a rougher surface will show a lowerresolution than that lost from not having complete contact, as do the High and UpperNegatives. Paper selection should take the resolution into account.

Figure 6: Pt/Pd prints from the sister original in camera negative (left) and from a digitalnegative stack without correction other than calibration (right).Note that the print from the digital negative shows posterization, and a loss of detail(branches in lower right) and texture (large metal areas). Because the sisternegative was exposed at different moment, the lighting has moved in the image.


13.16

CALIBRATION PROCEDURE:These calibrations should be completed in the same order that they are presented here. Thecalibration is based on an already determined Pt/Pd procedure of fixed materials and methods. Anydeviations from this fixed Pt/Pd procedure may require a new calibration or adjustments. Theexamples and actual values given are specific to the materials, equipment, and settings used for thisprocedure and may differ. It is imperative that one do their own calibration.

Only the final Pt/Pd print can accurately depict results, and only final Pt/Pd prints are used to makedecisions concerning calibration and the procedure. Calibration of the monitor is only necessarywith a desire to preview the image on screen and may be beneficial to preview creativemanipulations. The monitor should not be used for calibration.

It is important that all equipment be synchronized so as to not arbitrarily alter selected color values.This can be accomplished through color management selections. All equipment used was set tofunction under sRGB color management as default. Also, some Photoshop parameters and settingsmust be carefully controlled.

Important NOTE: This procedure and examples herein discussed produce a full range print. Ifanother range is desired, modifications should be made and calibrations and settings should bealtered accordingly. For example, if one wishes a limited range print (such as restricted to ZonesIV to VI), the maximum black threshold can be raised and the maximum ink density lowered whichwould preserve achieving the most individual tones.


13.17

Color Mix Calibration:The purpose of the Color Mix Calibration is to utilize more than one ink for a more diverse set ofprintable ink tones while making sure that colors (tones) do not become altered by being out ofgamut. Most printer drivers and Photoshop will change an out of gamut color to a closest colorwithin gamut. This can cause several tones to be represented as a single tone.

Note: The RGB color setting and profile must be set to sRGB which is the default factory settingfor the HP DeskJet 970 printer. If another printer is used with a different color setting, usethat color setting throughout.

� open original gradient (see Gradient Appendix);

� change to 16-bit mode;

� View, New View to create a new view;� For the new view: select View, Gamut Warning and View, Preview, Cyan.� Make sure the preference setting for gamut color is cyan.

� change to CMYK mode;

� Image, Adjust, Channel Mixer - adjust as follows:Output SourceCyan Cyan=0, Magenta=0, Yellow=0, Black=0Magenta Cyan=0, Magenta=0, Yellow=0, Black=+100Yellow Cyan=0, Magenta=0, Yellow=0, Black=+100Black Cyan=0, Magenta=0, Yellow=0, Black=0Note: This mix of color should produce some out of gamut steps on the gradient for

a sRGB color setting.

� change to RGB mode;

� check the new view image for any out of gamut indication (any cyan, even slight);Note: The gamut can only be checked in RGB mode.

� change to CMYK mode;

� Image, Adjust, Channel Mixer - Vary the Black source amount for outputs Magenta orYellow, switch to RGB mode, check gamut, and repeat until the entire gradient is withingamut (no Cyan on the new view);

� change to 8-bit mode;

� print.


13.18

� Repeat with another mixture until the color mixture producing the smoothest and mostcomplete gradient is found. The goal should be to use as much ink as possible whileremaining within gamut and producing a gentle gradient.

Note: This example settled on the following mixture:Output SourceCyan Cyan=0, Magenta=0, Yellow=0, Black=0Magenta Cyan=0, Magenta=0, Yellow=0, Black=+90Yellow Cyan=0, Magenta=0, Yellow=0, Black=+100Black Cyan=0, Magenta=0, Yellow=0, Black=0

� Save the Channel Mixer settings for easy recall as these will be applied as a standard toevery negative.

Note: It may be necessary to start over and redetermine the Color Mix, if the Base Curveapplied later throws the colors out of gamut.

� Save the color mixed gradient for use in the calibration of the Maximum White andMaximum Black Threshold calibrations.

Figure 7: Original gradient (top) - Gradient after Color Mixing (bottom).


13.19

Maximum Black Calibration (1st of 2 parts):Calibration of Printing Exposure:

� Make a Pt/Pd print using a stack of three pieces of blank substrate intended for the digitalnegative covering half the coated area. Expose at various times incremented by 0.5 stopintervals (steps). Choose times so that at least two steps are identical between the areascovered and uncovered by the substrate;

� Select the step with the longest exposure that is identical between the areas covered anduncovered by the substrate;

� Including and starting with the selected step, make another print with at least five exposuresat increasing increments of 0.1 stops;

� Select the step with the longest exposure that is identical between the areas covered anduncovered by the substrate. The exposure of this step is the Printing Exposure. This willassure that Maximum Black is possible in the print with the shortest exposure. The blackchosen for Maximum Black will likely not be the absolute black the materials are capableof producing, but should be reasonably close.

Figure 8: Determining Printing Exposure to give Maximum Black for the substrate used. Thebottom is an enhanced copy of the top in order to better discern differences. Notethe horizontal pencil marks on the sides indicating the edge of the substrates. Forthe example, the Printing Exposure is determined to be at most 6.5 minutes (as 6.0minutes shows slightly lighter, and 7.5 minutes is about the same). Note that thematerials may produce even more density beyond Maximum Black.


13.20

Maximum White Calibration:This will adjust the maximum amount of ink the printer will be set to print which will govern theMaximum White produced for the determined Printing Exposure.

� In Photoshop, Open the gradient produced in the Color Mix Calibration;Note: The densest portion of the gradient should produce Maximum White in the Pt/Pd

print.

� Increase the Canvas Size, Copy, and Paste so that three gradients are on the page;

� Print (using settings indicated in setup above).

� Separate and register the three gradients and tape together.

� Place an opaque sheet adjacent to and along one side of the composite gradient.

� Make a Pt/Pd print with the coating behind the gradient and opaque sheet, exposed for thePrinting Exposure determined above.Note: One of the final gradients will be used later for the Maximum Black.


13.21

Threshold and Base Curve calibrations.Using the Pt/Pd print, find the position on the gradient at which there is only the slightest differencebetween the gradient and the opaque sheet. If this position is not adjacent to the end of the gradient(highest density), then go to �DECREASE� below. If there is no white on the gradient, go to�INCREASE� below.

INCREASE:� In Photoshop, in the Printer Setup, set the Ink Volume heavier or select a paper that is setup

to use more ink (matte or plain papers are generally set by HP to use more ink).

Note: Finer control is achieved by going heavier than necessary and then reducing the inkby the Transfer Function in Page Setup. To do so reduce the 100% value to a lesservalue.

DECREASE:� In Photoshop, in the Printer Setup, set the Ink Volume lighter or select a paper that is setup

to use less ink.Note: For fine adjustment, in Page Setup, use the Transfer Function to reduce the

maximum amount of ink. To do so reduce the 100% value to a lesser value.

� Repeat the above until the Pt/Pd print shows Maximum White (paper white) only at thedensest step of the gradient.

Note: Too much ink can result in the ink puddling which may cause defects in thehighlights of the print. These defects can be spotted if desired. Too little ink willprevent a pure white from being produced in the print. The elimination of the unusedinks, cyan and black, helps to reduce the total volume of ink and helps preventpuddling. Puddling can be checked as outlined in the Puddling Appendix.

Figure 9: Using Pt/Pd print of the gradient to determine Maximum White (red indicator) foradjusting maximum deposition of printer inks. This example used the equipmentsettings described above.


13.22

Maximum Black Calibration (2nd of 2 parts):Calibration of Maximum Black Threshold:

� Retrieve one of the final gradients also containing blank substrate from the Maximum WhiteCalibration above and use it, stacked with two blank substrates, to make a Pt/Pt print usingthe Printing Exposure determined above.

� Using this Pt/Pd print, find the position on the gradient at which there is discernibledifference between the gradient and the blank substrate. The step, at this position, is theMaximum Black Threshold.

� Measure the distance from one end of the gradient.

� Using Photoshop's Dropper Tool, find the step in the gradient which corresponds to thisposition. Set dropper to the position and read Magenta and Yellow values. These are theMaximum Black Threshold values. This relates to the minimum amount of ink necessaryto properly print the built negatives. Any amount of ink density less than this value will notcontribute to tonal separation in the print. A threshold placed too low will cause lowershadow values to merge into Maximum Black and also result is a loss of the total numberof tones available. A threshold placed too high will result in a loss or lessening of theMaximum Black available in the print. Keep in mind that all inks do not transmit identicallyand perhaps not even linearly.

The Maximum Black Threshold, for this example, is achieved with color values of 38%Magenta and 42% Yellow.

� The Maximum Black Threshold is applied in the Base Curve Calibration (below).

Figure 10: Comparison of the Pt/Pd print of the gradient with Maximum Black to determine theMaximum Black Threshold. The Maximum Black Threshold is measured, in thiscase to be 7.60 inches from the left edge (red indicator) of the Maximum White finalgradient. The bottom of the figure is a copy of the top with levels adjusted so as tobetter discern the Maximum Black Threshold point.


13.23

Figure 11: The values of the Maximum Black step are determined using Photoshop's DropperTool with the Color Mixed gradient. The 7.60 inch position (red indicator) of theMaximum White final gradient has color values of 38% Magenta and 42% Yellow.For this example, these color settings on the Base Negative will provide theMaximum Black Threshold in the Pt/Pd print.

Base Curve Calibration:This produces a standard curve to be applied to every Base Negative. The purpose is to set theMaximum Black Threshold without losing the Maximum Black and provide the desired shadowdetail. There are three ways to accomplish this. This method guarantees not losing the MaximumBlack in the print.

The selection of the value to place at the Maximum Black Threshold is an important choice. Thisvalue along with the selected Maximum Black Threshold are a personal preference of eachphotographer. Once selected and maintained constant, they will provide a consistent calibration. One should consider a value which is low but should also consider that better separation will comefrom values denser than the toe of the film used for the original negative. The placement of aMaximum Black Threshold at a certain density value of the film will influence how that film is usedto store the image information. Remember that any densities less than the Maximum BlackThreshold are merged with Maximum Black. For a print tone to be lighter than Maximum Black,the corresponding original negative portion must receive enough exposure to produce a densityabove the Maximum Black Threshold.

The following are the three options to generate the calibrated Base Curve.OPTION A: (using Color Mixed gradient)OPTION B: (using an original negative) recommendedOPTION C: (using a 21-step original)


13.24

OPTION A: (using Color Mixed gradient)This option is straight forward and the easiest and assumes that perfect, optimized original negativeswill be used.

� Begin with the Photoshop file of the final gradient from the Maximum White Calibration.

� In Photoshop, Image, Adjust, Curves;

� For CMYK, leave as straight 1:1 line.

� In Cyan and Black channels, change all output to 0.

� In Magenta and Yellow channels, enter a curve such that:

� Leave 0 and 100% points as they are.

� Enter the Magenta and Yellow values of the Maximum Black Threshold as the output valuesfor the input values of 5%.

� Add two points above the Maximum Black Value so that the curve above this value isforced, as much as practical, into a straight line.

This will provide for discernible shadow tones while maintaining the Maximum Black, ata minimum expense of the 256 data steps available. The input value of 5% is used in orderto work with a manageable curve. Input values less than 5% may require several morepoints to keep a straight line and may not provide enough opportunity for Maximum Blackto appear in the print.

� Apply the curve after saving the curve information;

� change to RGB, 8-bit;

� check to make sure the entire image is within gamut (using View, Gamut Warning and View,Preview, Cyan);Note: If the image is out of gamut, the Color Mix should be reselected and all calibrations

repeated except for the Printing Exposure.

� Print the file.

� Make a Pt/Pd print of this gradient stacked with two blank substrates.

� Evaluate the Pt/Pd print.The steps of the printed gradient should all be discernibly lighter than Maximum blackexcept for the densest end step which should be Maximum Black.


13.25

� Adjust the Base Curve as needed to change any base values, reprint, and reevaluate.

� Save the final Base Curve as the standard Base Curve to apply to all Base Negatives.

Figure 12a: Color Mixed gradient. The red mark identifies the Maximum Black Threshold.

Figure 12b: Color Mixed gradient with Base Curve applied. The red mark identifies theMaximum Black Threshold.

CLICK HERE to view the Base Negatives and Pt/Pd prints comparing the three Base Curve Options.

http://jeffreydmathias.com/guide/base_curve_options.htm


13.26

OPTION B: (using an original negative) recommendedThis option is a little more difficult than Option A and customizes the curve to an original negative.The original negative should be typical of other original negatives to be used, as the Base Curveproduced will be customized for this original negative only.

� Follow the procedure, through Channel Mixing, to make only the digital Base Negativeusing an original negative typical of others to be used. As a standard use a full rangeoriginal negative that has been optimized for the scanner. (The High and Upper Negativesare not needed at this time.)

� In Photoshop, Image, Adjust, Curves;

� For CMYK, leave as straight 1:1 line;

� In Cyan and Black channels, change all output to 0;

� In Magenta and Yellow channels, enter a curve such that:

� Leave 0 and 100% points as they are.

� The lowest density of the original negative that will print just discernibly lighter than blackshould have an output value of the Maximum Black Threshold, Magenta and Yellowcomponents. Use the dropper to select the portion of image to identify the input values andtheir position on curve, then enter the Magenta and Yellow output values for that curveinput. This requires a decision to select the values of the original negative to be set to theMaximum Black Threshold. Keep in mind that the decision at this point is to generate astandard condition to be applied to all similar originals; other decisions can be made laterduring creative control.

� Add two points above the Maximum Black Value so that the curve above this value isforced, as much as practical, into a straight line.

This will provide for discernible shadow tones while maintaining the Maximum Black, butlikely at the expense of several of the 256 data steps available. In comparing Figure 14awith 14b, it is observed that the selection of the density to place at the Maximum BlackThreshold will have some basic results.

� The lesser the original negative density chosen for Maximum Black Threshold, thelower the local contrast of the base values will be in the print. Note that the contrastof the base may also be changed by selecting a different base/high split duringscanning, however this split may also affect (or trade off for) contrast in the high andupper areas.

� The higher the original negative density chosen for Maximum Black Threshold, the


13.27

more information of the original negative and the more number of tones in the finalprint will be lost.

� Apply the curve after saving the curve information;


� check to make sure the entire image is within gamut (using View, Gamut Warning and View,Preview, Cyan);Note: If the image is out of gamut, the Color Mix should be re-selected and all calibrations


� Print the file.

� Make a Pt/Pd print of the Base Negative stacked with two blank substrates.

� Evaluate the Pt/Pd print.Any potion of the print to be discernibly lighter than Maximum Black must be placed at orabove the Maximum Black Threshold.

� Adjust the Base Curve as needed to change any base values, reprint, and reevaluate.

� Save the final Base Curve as the standard Base Curve to apply to all Base Negatives forsimilar original negatives.


13.28

Figure 14a: A higher lower density is selected from the original. The tone selected from theColor Mixed Base Negative to be set to the Maximum Black Threshold (circled inblue on left) has color values of 35%M 40%Y. These values are adjusted to theMaximum Black Threshold values of 38%M 42%Y (determined by calibration above)in creating the Base Curve adjusted Base Negative (middle). This Base Negativeproduces the Pt/Pd print detail at right.

Figure 14b: A lower lower density is selected from the original. The tone selected from the ColorMixed Base Negative to be set to the Maximum Black Threshold (circled in blue onleft) has color values of 19%M 21%Y. These values are adjusted to the MaximumBlack Threshold values of 38%M 42%Y (determined by calibration above) increating the Base Curve adjusted Base Negative (middle). This Base Negativeproduces the Pt/Pd print detail at right. Note the better discrimination of dark valuesusing the lower lower density.

CLICK HERE to view Pt/Pd prints comparing the three Base Curve Options.



13.29

OPTION C: (using a 21-step original)This option is a good way to investigate how the steps may be manipulated or for comparing originalnegatives of various theoretical dynamic ranges. However, it is only useful for establishing a BaseCurve based on a theoretical original and is the most difficult of the options.

� Use a 21-step in place of the original negative.

� Make a Base Negative following the procedure stopping after Color Mixing.

� Save this 21-step Base Negative.

� Change to RGB, 8-bit, and Print.

� Make a Pt/Pd print of the Base Negative stacked with two blank substrates and the 21-step.

� Evaluate the Pt/Pd print.The lower density steps of the base tone negative should be identical to the respective stepsof the 21-step with step 2 slightly discernible from step 1 (Maximum Black)

� Calculate or guess a factor to bring each Base Negative step to match the 21-step in the print.Only do this for the lower density steps. Only an approximation is needed at this point.

� In Photoshop, Open the Color Mixed Base Negative, and use the curve adjustment (Image,Adjust, Curves) as follows:� For CMYK, leave as straight 1:1 line.� In Cyan and Black channels, change all output to 0.� In Magenta and Yellow channels, enter a curve such that:� Leave 0 and 100% points as they are.

� Use the dropper to select steps of the 21-step to identify position on curve, then enterthe Magenta and Yellow output values for that curve input that was assumed aboveto produce identical values when printed again with the 21-step.

� apply the curve after saving the curve information;


� check to make sure the entire image is within gamut (using View, Gamut Warning and View,Preview, Cyan);Note: If the image is out of gamut, the Color Mix should be re-selected and all calibrations


� Print the file.


13.30

� Make a Pt/Pd print of the Base Negative stacked with two blank substrates and the 21-step.

� Evaluate the Pt/Pd print.

� Repeat adjustments of the curve until the print shows no difference between the digital BaseNegative and the 21-step for the darker values only. Do not consider how the negativescompare, only the Pt/Pd prints.

� When identical, save as the 21-Step Base Curve. The 21-Step Base Curve may be used asthe Base Curve, if it is assumed that the film and processing used for the original negativerespond identical to the 21-step. With the 21-step, one has an entire set of fixed densitysteps to investigate variations throughout the entire digital negative procedure. High andUpper tones can be investigated as well. For many investigations, it is simple to comparetone steps.

Figure 15a: 21-step after Color Mixing

Figure 15b: 21-step after setting step 2 to the values of the Maximum Black Threshold.

CLICK HERE to view Pt/Pd prints comparing the three Base Curve Options.



13.31

Building Density StepsBuilding a GradientOptimizing the Original Negative for Scanner NoisePuddlingRegistrationResolutionSharpening

Appendices to Building Digital Negativescreated September 2000, updated April 2001

Building Density Steps:Density Steps are used during Curve Calibration in place ofan original negative. It is important that Density Steps bebuilt using the same film, chemistry, equipment, processing,and exposure as would a typical original negative.

The steps are exposed as follows:

Step 1 - no exposureStep 2 - exposure that will produce the Maximum Black ThresholdStep 3 - metered to produce Zone IStep 4 - metered to produce Zone IIStep 5 - metered to produce Zone IIIStep 6 - metered to produce Zone IVStep 7 - metered to produce Zone VStep 8 - metered to produce Zone VIStep 9 - metered to produce Zone VIIStep 10 - metered to produce Zone VIIIStep 11 - metered to produce Zone IXStep 12 - metered to produce Zone XStep 13 - metered to produce Zone XIStep 14 - metered to produce Zone XII

Note that there may not be a one stop difference from Step 1 to Step 2 or from Step 2 to Step 3 andthere is a one stop difference between the other steps. The Maximum Black Threshold is selectedby personal preference, keeping in mind the ramifications outlined in the Calibration Procedures.There are many ways to accomplish the exposures including individual frames or the positioningof a film holder slide.

Processing and exposure must be that given for a typical for a full range negative with typicalnormal contrast and as would be used to scan and produce digital negatives. This includesaccounting for Optimizing the Original Negative for Scanner Noise.


13.32

Building a Gradient:The gradient and step bars built here are used throughout the digital negative calibration procedure.The 1% step gradient will be the most useful during calibration.

� In Photoshop, Open a new image 10 inches high by 0.5 inch wide at 600 ppi in RGB mode;� set the background color to C0-M0-Y0-K0;� set the foreground color to C0-M0-Y0-K100;� build a 0.5 inch wide, 10 inch vertical gradient bar using the Gradient Tool;� save this as the Photoshop gradient;� change the canvas to 10 inch by 1.5 inch keeping the gradient to one side;� Open a new image 10 inches high by 0.5 inch wide at 600 ppi in RGB mode;� in the new area select 100 adjacent areas of 0.1 inch by 0.5 inch and fill with 1% increments

of density with the paint bucket, one at a time.� save this as the 1% gradient;� select all, copy, paste, and move opposite the Photoshop gradient;� using the 1% gradient select five blocks at a time and fill with 5% increments of density;� save this as the 5% gradient;� select all, copy, paste, and move between the other gradients;� flatten and save as the Original Gradient.

Figure adn1: Photoshop gradient, 5% step gradient, and 1% step gradient subsequently calledOriginal Gradient


13.33

Optimizing the Original Negative for Scanner Noise:Just as it is so very important to customize the original negative for the selected printing process,so too it is important to produce the proper negative for scanning. Those who have used a scannerto record the information from a negative should be familiar with the relationship that bit depth ofthe scanner must be increased as the dynamic range of the negative increases. If the bit depth doesnot increase, vital information from the negative will be omitted from the scan. This informationlikely first disappears under a level of noise. Next the information becomes limited because acertain number of bits can only provide a certain number of tones and the image requires a certainnumber of tones be present so that posterization effects are kept hidden. Posterization is noteliminated in a digital negative, only minimized to a fine enough level. (The actual desirablenumber of tones is not known at this point.)

To determine proper dynamic range and processing requirements of the negative, several negativeswere made at the following developments. The film used was 4x5 Kodak Tri-X exposed at200ASA. The first number is development time in minutes with continuous gentile agitation in atray (one negative at a time). The second number is the concentration of the HC-110 developer inml/litter. A Zone VI temperature compensating timer was used.

3@324@325@326@324@645@646@647@64

A typical full range Pt/Pd print would have the negative processed at 5@64 (this may vary with theuse of different equipment, Pt/Pd materials, or procedures). The dynamic range of these negativesincreases as one moves down the list. This is the usable, practical dynamic range. Any rangeadjustment due to base plus fog is considered negligible for this study. Any density beyond thatrelated to Zone XII is dismissed as not practical to use. Zone XII is considered because a palladiumprint can easily produce all those zones.

Each of the negatives was scanned with 12-bit pixel depth and converted and stored as 8-bit (the wayof the HP ScanJet 6300). The closest negative with the highest dynamic range and without noise inthe highlights was found to be 5@32 (this is about half the processing given to a typical Pt/Pdnegative). The noise would appear at the same density, so as each negative that had more dynamicrange, more of the upper end would consist of noisy data.

Data from two of the negatives can be found below in Figure adn2.

It is true that the noise can be smoothed out with various software techniques, but regardless theoriginal data covered by the noise is corrupted and lost.


13.34

A similar evaluation can be made by scanning a Stouffer 21-step. Find the densest step that doesnot show noise and that density will relate to the maximum density of a film processed a certainway. Note that the actual film used is a better test as the characteristics of the Stouffer 21-step maybe different, however densities can be evaluated fairly easily with the Two Hole Method. Anexample using the 21-step can be found below in Figures adn3 and adn4.

CONCLUSION:In order to get optimum results it is recommended to match the negative's dynamic range with thescanning equipment used. A dynamic range too high will result in the loss of information, mostlikely from the highlights. A dynamic range too low will result in wasted data capacity. It wouldbe preferable to error too low so as to maintain image integrity.

Notes: One must test their own negatives as many parameters are capable of influencing the results.

One must keep in mind that the examples here only deal with the noise level and that actualprints must also be made and evaluated from digital negatives produced by a consistentprocedure.

Just to give something additional to ponder:It is guesstimated that a typical negative made for Pt/Pd printing would require 14-bit data withoutnoise. If it is assumed that 2 bits will contain noise (typical), then a 16-bit scanner should be soughtif one wishes to scan negatives that also typically are used to print with the Pt/Pd process.

More to ponder:It is not known if or what differences a Pt/Pd print may exhibit between using a 16-bit scan fromappropriate negative and a 12-bit scan from appropriate negative. It is suspected that a negative witha higher dynamic range may enable a higher print quality. It is not known, but could be possible thatthis is part of the reason for a Pt/Pd print to have better tonal separation than some other processes.This comparison could also be made controlling built analog negatives.


13.35

Scanner Noise in scanned negatives:

Figure adn1: Negative (5@32) processed at half that typical for Pt/Pd (left). Negative (5@64)processed as typical for Pt/Pd (right). Note corruption of critical highlights (not purewhite sky). The two 4x5 negatives are scanned with a 12-bit scanner, with allfeatures such as noise reduction and sharpening turned off, and the exposureadjustment set full range, and at 1200 ppi, full color with zero saturation. A portionof each negative containing some critical highlight values is cropped and compared.The levels are then adjusted to better view the noise. The banding patterns are anindicator of noise, likely due to a low signal level of the detectors.

Figure adn1b: Full 4x5 negative indicating the portion in the upper right selected for the detail.


13.36

Scanner noise in Stouffer� steps:

Figure adn3: A 21-step is scanned with a 12-bit scanner, with all features such as noise reductionand sharpening turned off, and the exposure adjustment set full range, and at 1200ppi, full color with zero saturation.

Figure adn4a: The lowest density step containing noise is identified.

Figure adn4b: The levels are adjusted to better view the region around this step.

Figure adn4c: Each step is adjusted to a similar brightness so that the texture may be clearly seen.The banding patterns are an indicator of noise, likely due to a low signal level of thedetectors. In this example, step 12 is the density at which the noise level just beginsto cover subtle tone variations.


13.37

Puddling:Puddling is the result of ink flowing on the substrate in areas significantly larger than the desiredresolution. The follow is used to check both Puddling and resolving ability.

� Make some resolution targets as in the Resolution Appendix.

� The target is then printed and the output studied for puddling.

[figure to be added]

Figure adn5: Printed targets demonstrating no puddling (left) and puddling (right).


13.38

Registration:The following are registration procedures for two methods of digital negative building.

Stacked Negative registration begins with the formation of alignment marks on the negatives.

� A boarder is formed around the original when the three scans are made. It is important thatall scans are made over the exact same area.

� In Photoshop, all scans are opened and a new blank layer is opened for one of the scans;� 1 pixel width lines are made along each edge with the line tool so that they cross at the

corners.� The layer is selected (all) and copied.� For each of the other scans, they are selected (all) and the layer pasted into the selection.� Each of the three scan images is flattened and saved as the original .tif file.� The three negatives are printed as per procedure.

Figure adn6: Detail showing a corner of a scan with registration marks added.

Next the negatives are stacked in registration.� Place the base negative on the light table (ink side down).� Place the high negative on the other, allign (using a magnifier), and tape.� Place the upper negative on the stack, allign (using a magnifier), and tape.

The negatives are now ready to use for exposure.� After coating the paper in the appropriate area, the stack is place over the coating as would

be done with a single negative and placed into the contact print frame.

Registration in this manner is as accurate as the printer and the magnifier allow.

Tri-Negative registration begins with the formation of alignment marks on the negatives as above.Follow the seven steps above figure Reg1.

� Next the negatives and paper are indexed and registered. After the three negatives areprinted, they will be stacked on a light table and aligned using a magnifier, again similar toabove. Tape is used to hold them in place.

� A sheet of paper (to which the Pt/Pd coating will later be applied) is placed together with the


13.39

stack (ink sides toward paper), the approximate area to be coated is marked, and the stackis taped to the paper.

� The stack of negatives along with the piece of paper will have two adjacent sides trimmedat a right angle. The dimensions of the negative stack and paper must be less than thecontact print frame.

� All tape is removed and all pieces separated.

The negatives are now ready to use for exposure.� After coating the paper in the appropriate marked area, the first negative and paper are

placed into the contact frame with the cut sides contacting the printing frame. The printingframe can be modified by installing two small metal or wood stops on each of the sides (thisis only neccessary if the sides of the printing frame sides are not straight and square).

� After exposure of the first negative, that negative is removed and the second negativeinserted with the cut sides contacting the same sides of the printing frame.

� After exposure of the second negative, that negative is removed and the third negativeinserted with the cut sides contacting the same sides of the printing frame.

Registration in this manner is as accurate as the printer, cutting, contact frame, and the placementof paper and negatives into the frame. However, the substrate used for the Pt/Pd coating must berigid. If a fabric or thin paper is used, it should be taped to a rigid card or paper that is indexed tothe printing frame.


13.40

Resolution:The resolution should be ultimately determined by the substrate selected for the Pt/Pd print, it isimportant to have enough resolution in the scans of the original negative as well as the prints of thenegatives. Look below for a comparison of prints using digital negatives as a function of theresolution at which the digital negative is printed. A resolution of 600 ppi for the final print sizeseems to be a good choice.

� In Photoshop open a new file with a resolution of 600 ppi (or higher, if the equipment iscapable).

� Using the line tool draw several lines with a width of 1 pixel and spaced 1 pixel.� Using the line tool draw several lines with a width of 2 pixels and spaced 2 pixels.� Using the line tool draw several lines with a width of 4 pixels and spaced 4 pixels.� This will produce targets of 600 lpi, 300 lpi, and 150 lpi respectively. (lpi = lines per inch,

lines are both black and white).

Figure adn7: Targets of 600 lpi, 300 lpi, and 150 lpi (enlarged)

� Print the targets as a digital negative.� Use the negative to make a Pt/Pd print.� Compare.

Figure adn8:1200 ppi scan of Pt/Pd printed targets(enlarged to 72 ppi) The substrate isCrane's "Cover-90" paper. The HewlettPackard DeskJet 970 (used to print thedigital negative) has a benefit of beingcapable of printing the same lpi (lines perinch) as the dpi (dots per inch). When thispaper is to be used with a negative from thisprinter, scan resolution should be 600 ppiand printer resolution 600 lpi.


13.41

Figure adn9: Comparison of Pt/Pd prints from digital negatives printed at various resolutions.

The original Pt/Pd print detail (left) is from a print of the sister original negative. The othersare details of the Pt/Pd prints from digital negatives printed at the indicated resolutions. Theoriginal negative scan was at a resolution of 600 ppi. The Pt/Pd print details were allscanned at 1200 ppi and sharpened an equivalent amount.

Note that the original contains much more detail. This level of detail may be hard to discernwhen viewing the actual 4x5 print. However, there is a noticeable difference in texture andtactile quality amongst the prints. It is possible that some lack of detail may be due to slightregistration misalignment of the negative stacks. The higher resolution negatives were easierto register. The 300 ppi and 150 ppi negatives had more sharpening applied than those of600 ppi (some bar effect is noticeable). [It is recommended to use minimal sharpening foractual negatives.]

It is also noted that the printer may not have been producing the 600 lpi it is supposed to,which could likely be due to dot gain. Although tests at the maximum ink levels showed theprinter to print lines at 600 lpi resolution without puddling or blotches.


13.42

Sharpening:Sharpening should be kept to a minimum and an adequate sharpening threshold level used to helpavoid posterization. It seems that any amount of sharpening will tend to encourage posterization.Setting the sharpening threshold to higher values may help reduce posterization. It might be bestto not apply any sharpening.


14.1

Chapter 14 - TestingTesting the Ferric Oxalateupdated December 2000

This test is comprised of three tests and two functions. The accomplishment of both functions iscritical to the passing of the Ferric Oxalate solution. A solution should be made up containing onlyFerric Oxalate without any additives so as to not introduce other possibilities. Later actual sensitizersolutions can be tested to determine if any additives adversely affect the function of the FerricOxalate.

Note: Testing, as with any handling of Ferric Oxalate, should be carried out in safelightillumination.

In order to pass this test, the Ferric Oxalate solution must first NOT turn color. This demonstratesa desired lack of ferrous material that may be present from contamination or exposure fogging.Second, the solution must turn color to indicate the proper conversion to ferrous when called for.

To test the Ferric Oxalate solution:

PART I - TEST (#1, #2 or #3)� Place some Ferric Oxalate solution into a shot glass.� Add a crystal of Potassium Ferricyanide (one or two crystals is plenty to do the job).

� Nothing should happen. Test Part I PASSES if nothing happens.� TEST FAILS if the solution darkens (do not consider any natural orange or red color

from the Potassium Ferricyanide, the failure color is likely to be blue, gray, orindigo). The solution likely contains Ferrous Oxalate.

TEST #1TEST #1 FAILS:� If TEST #1, FAILS and the solution is OLD SOLUTION, the solution is defective.

This can be caused from heat, exposure to light or old age.� Make a fresh solution from the stock powder and test again (TEST #2).

� If TEST #1, FAILS and is NEW SOLUTION, then the stock powder is defective.

� If the defective stock powder is OLD POWDER, then it has probably beenstored incorrectly. Heat, moisture or light exposure can cause a powder togo bad.

� If the defective stock powder is NEW POWDER, then the powder should bereturned to the vender for replacement.


14.2

TEST #1 PASSES:� If TEST #1 PASSES, continue test PART II with the same solution.

TEST #2TEST #2 FAILS:� If TEST #2 FAILS and the stock powder is OLD POWDER, then it has probably

been stored incorrectly. Heat, moisture or light exposure can hurt a powder.� Make a new solution using new stock powder and test again (TEST #3).

� If TEST #2 FAILS and the stock powder is NEW POWDER, then the powder isdefective and should be returned to the vender for replacement.

TEST #2 PASSES:� If TEST #2 PASSES, continue test PART II with the same new solution.

TEST #3TEST #3 FAILS:� If TEST #3 FAILS, then the new powder is defective and should be returned to the

vender for replacement.

TEST #3 PASSES:� If TEST #3 PASSES, continue test PART II with the same new solution from the

new stock powder.

PART II - TEST

� PART II Place shot glass with Solution in UV light.� The solution should turn deep indigo blue.� If the solution does not turn a deep indigo blue, then the Ferric Oxalate is bad.

� If this is a NEW SOLUTION from a NEW POWDER, first try adding somemore Potassium Ferricyanide. If there is still a failure to turn blue and thePotassium Ferricyanide is good, then the powder is not Ferric Oxalate.Return the powder to the vender for replacement. (If this happens again, finda new vender.)

� If this is a NEW SOLUTION from an OLD POWDER (that has workedbefore), then somehow the solution was made incorrectly. Make a newsolution from the old power and re-test.

� If this is an OLD SOLUTION from an OLD POWDER (that have both


14.3

worked before), then the Potassium Ferricyanide must be bad. (This isunlikely , but there is no other reason.)

� When the solution turns dark blue only after exposed to light, then the TEST hasPASSED and the Ferric Oxalate is OK to use in a sensitizer solution.


14.4

Fogging Testcreated August 1999, updated December 2000

It is important to work with light sensitive materials in conditions which do not adversely affectthose materials. Of the most common is fogging from stray light or an inappropriately chosen worklight.

Testing for fogging is straight forward and should be performed whenever a new work light or newmaterial is put into use. It is especially important to have conditions which have passed the foggingtest when running a clearing test since fogging could be mistaken for incomplete clearing.

Before having an opportunity to write up a testing procedure for fogging, a great procedure wasmentioned by a fellow Pt/Pd printmaker. The following fogging test description and explanationis presented with permission from its author, Tom Ferguson.Tom�s web site is at http://www.thefstop.com/tf.html

I'm a big fan of people doing tests themselves, rather than simply taking other peoples "word". Onelearns soooo much more that way! There are simply too many variables in this world. Does mylight bulb enclosure block more UV than yours?? Are South American light bulbs different inoutput than USA bulbs?? Is a Philips 75W bulb different than a GE?? So I do suggest that anyonecoating paper do a simple fog test.

Coat a piece of paper (in the dark) and find the exposure without a negative (in your usual UV lightsource) that gives the first barely visible gray in a processed and dried print. Next coat another piece(in the dark) and give it this same exposure, but don't process it. Now cut this paper into 3 pieces.Put a large heavy coin on each piece of paper and leave it in your room with the desired lights on.Label and remove one after 15 minutes, another after 30 minutes, the last after an hour.

Process and dry the test prints, and see if the coin's shadow shows as a lighter tone than the rest ofthe test print.

Why go to the trouble of pre exposing to "first barely visible gray"? I know, a few books don'tbother with this step! Most, if not all, light sensitive materials have a "threshold" that must bepassed before they start to react. What follows will not be correct to a knowledgeable scientist, butthe ideas are sound.

It takes some number of photons hitting the emulsion to turn it on. Say that number is 10. If yoursafe light gives 9, then you don't see fogging. But then you put it, with your negative, into the UVand expose. That highlight you wanted as paperbase gets 5 photons threw the negative, It has nowgotten 14 photons, and prints as a slight gray, rather than paperbase. Opps, fogging where you didn'tthink it would be. If we pre expose the test paper to a "first barely visible gray", then any additionalphotons affecting the paper will be visible.


14.5

Test for Clearingupdated September 1999, December 2000

Clearing times may be ascertained by this test. It is recommended that this test be performed everytime a new paper or coating chemistry is to be tried. Also use this test before a new type of clearingagent is used. It is highly recommended to first perform the Fogging Test as fogging could bemistaken for a lack of clearing.

Notes: Safelight illumination must be used for all coating and processing during this test. Only turnon other lights after paper is in the wash water.

This clearing test procedure has been updated in September 1999 with the addition of the useof an indicator of Potassium Ferricyanide after an exposure after the clearing procedureunder evaluation. This indicator was designed and suggested by John Melanson.

Caution: This indicator is extremely sensitive and may produce a false reading. It issuggested that an uncoated control be used as a reference. The solutionstrength of the indicator can be reduced to 1%.

The addition of this indicator has made this test much more sensitive to detecting an incompleteclearing. John Melanson has demonstrated that several clearing solutions which had removed alltraces of yellow and gray and appeared cleared, showed blue or gray values with this indicator.

PROCEDURE:� Place a strip of removable tape on the selected paper.

Note: Removable tape is handy for this, but use caution to not damage or roughen the papersurface when removing.

� Coat the paper with a very definite edge to the coating formed by the tape. Do not let thecoating mixture puddle.

� Remove the tape.

� Dry carefully so as not to push the mixture into a puddle at the edge.Note: Puddling may cause a density at the edge of the puddle that typical clearing may not

remove as quickly.

� Mark the edge with a dotted pencil line(s). The purpose is to locate the position of the edgeafter clearing.

� Without any exposure, process the paper using the clearing procedure under evaluation,including any other processing typically given including development.


14.6

� Dry (hair dryer with heat may use used).� Evaluation is made at this point under white light.

Note: Direct sunlight may be too intense to evaluate. Shaded sunlight is OK.

� Look very closely along the edge delineated by the pencil line(s) for any differences.� Insufficient clearing will be seen as yellow, brown, or gray density in the coated

area.� Yellow or brown may indicate a presence of unreduced ferric oxalate or

metal salts.� Gray may indicate residual metal salts.� Examples of colors can be found in the Clearing Study.

� Even the slightest difference will indicate incomplete clearing. If not cleared, the indicatorportion of the test can be omitted. If there is no difference between the coated and uncoatedareas, continue with the indicator portion of the test.

INDICATOR PORTION OF TEST:� Expose with UV light source for twice the typical exposure.

� Place drops of 1% solution of Potassium Ferricyanide K3Fe(CN)6 onto a clean Q-tip orsimilar applicator, then spread onto the coating so as to straddle the edge of the coating,moving only from uncoated to coated area.Note: A puddle of a drop directly applied may allow activated indicator to move across the

edge.

� Wash for about 5-10 minutes to remover any yellow-orange base color of the PotassiumFerricyanide.

� Dry (hair dryer with heat may use used).

� Evaluation is made under white light.Note: Direct sunlight may be too intense to evaluate. Shaded sunlight is OK.

� Look very closely along the edge delineated by the pencil line(s) for any differences.

� Insufficient clearing will be seen as blue or gray density in the coated area.� Blue indicates a presence of ferrous reduced from ferric oxalate by the light.� Gray is thought to be from residual metal salts.� Examples of colors can be found in the Clearing Study.

� If there is no difference between the coated and uncoated areas, then clearing was successful.Even the slightest difference will indicate incomplete clearing.


14.7

It is best to determine and use the least amount of time necessary to clear a paper. However doremember that if the strength of the clearing agent is increased too high, then the paper may beadversely affected. It is also suspected that weak acid clearing baths work best.


15.1

Chapter 15 - StudiesEmpirical Verification of the POP Process Equationand Optimization of the Solutionscreated August 1999

What exactly occurs during the POP process is not fully known. In order to verify the POP ProcessEquation and optimize the solutions used in the coating, an experimental test was conducted.Conditions and parameters were carefully controlled and recorded. The ability to make consistentlyidentical prints is a must for this type of test. Evaluations were made based on the study of actualprints. Prints were compared side by side and with standard DOP prints.

Some of the data in this test were obtained as part of a larger more comprehensive study. Theinterest at this point was to study the Lithium double salt of Palladium and two types of sensitizeron three frequently used substrates and to verify empirically the process equations.

PROCEDURE:For these comparisons the following materials and conditions were used. Only Palladium solutionswere used; no tests were made with Pt so as to limit parameters. All subsequent reference is by therespective notations given.

SUBSTRATES:The following substrates were chosen as they are ones used often and represent some diversity.

B = Hunt Co., Bienfang 360CP = Crane's Parchment Business Card Stock (Lot No. 5302) ("Cover 90")SI = Sea Island Fabric

COATING CHEMISTRY:The notation used is [sensitizer - contrast agent - Pd salt - Pt salt]

sensitizer [# of drops, type], types used were:FO .......... Ferric Oxalate 27% solutionAFO40 ... Ammonium Ferric Oxalate 40% solutionAFO60 ... Ammonium Ferric Oxalate 60% solution

Pd solution [# of drops, type of salt, approximate % solution], type of Pd salt used was:Li ... Lithium - Li2PdCl4

Pt salt - none was used in order to eliminate a variablecontrast agent - none was used in order to eliminate another variable


15.2

The following coatings were evaluated for this test.6FO-6Li36-0-0 6AFO40-6Li36-0-0 6AFO60-6Li36-0-06FO-6Li30-0-0 6AFO40-6Li30-0-0 6AFO60-6Li30-0-06FO-6Li24-0-0 6AFO40-6Li24-0-0 6AFO60-6Li24-0-06FO-6Li18-0-0 6AFO40-6Li18-0-0 6AFO60-6Li18-0-06FO-6Li12-0-0 6AFO40-6Li12-0-06FO-6Li6-0-0 6AFO40-6Li6-0-0

AMBIENT CONDITIONS:Other testing and experience has shown the POP process to be only consistently dependable at anambient relative humidity (RH) below 65% and an ambient temperature below 75oF. The ambienttemperature for this study was between 68oF and 73oF. The ambient relative humidity was set at62% +- 3%.

EXPOSURE:Exposure was identical for all prints under artificial lamps (as described in this guide). This wasapproximately the exposure this negative would typically get. The time was kept constant so thatspeed and contrast could be readily compared using a 21-step. It would have been just as valid tomatch the print and 21-steps and note time differences, although it would have been difficult andcumbersome to accurately define any contrast differences. Consideration was made when evaluatingprints as to any differences in speed and contrast. Results have been verified using other negativesand printing times that give the optimum print.

PROCESSING:Processing was standardized but tailored for each type of substrate and sensitizer.

For FO on CP:Developer was Potassium Oxalate 1 minuteRinsed in tray of water for 2 minutesCleared in Phosphoric acid baths for total of 30 minutes

For AFO40 on CP:Developer was tray of water for 2 minutesCleared in Phosphoric acid baths for total of 20 minutes

For FO on B:Developer was Potassium Oxalate 1 minuteRinsed in tray of water for 2 minutesCleared in Phosphoric acid baths for total of 15 minutes

For AFO40 on B:Developer was tray of water for 2 minutesCleared in Phosphoric acid baths for total of 15 minutes

For FO on SI:Developer was Potassium Oxalate 1 minute


15.3

Rinsed in tray of water for 2 minutesCleared in Phosphoric acid baths for total of 12 minutes

For AFO40 on SI:Developer was tray of water for 2 minutesCleared in Phosphoric acid baths for total of 12 minutes

water = 0.5um filtered tap waterPhosphoric acid bath = 2oz 85% H3PO4 in 1 gal. waterThe clearing times were determined by the method outlined in this guide.

OBSERVATIONS:

EVALUATION:Prints were compared by looking at, after dry, in "normal" light and direct sunlight (reflected andtransmitted). The overall evaluation was to judge the quality of the print with emphasis on darkerareas. The same image of a dark stairway with lots of shadow details and texture was used. Alsoincluded in the print was a "21 step".

AFO40 SERIESThe series of AFO40 for Li6 to Li36 showed a transition from a noticeably week and muddy Li6print to a healthy Li24 print with no further improvements in the Li30 and Li36 prints. The AFO60-Li30 and Li36 prints showed a bit more substance. There was a definite distinction between theLi18 and Li24 prints. These results are significantly helpful as an empirical tool to finding theprocess equation (discussed later). These prints all had the same color and speed. The contrastseemed to increase about 1 grade mostly from Li6 to Li18 and a little more to Li24.

AFO40 vs AFO60A difference was noted between the AFO sensitizer solutions of 40% and 60%. Differences wereonly noted for the Li36 and Li30 coatings. No difference was detected for the Li24 and Li18coatings. (Recall that the number indicates the % solution of Li2PdCl4.) These findings proved tobe significantly helpful as an empirical tool to finding the process equation (discussed later). Dueto this importance, these prints were repeated and found to give consistent results.

A final comparison was made with the best of the AFO40 and AFO60 prints. Those were theAFO40-Li24 and the AFO60-Li36. These prints seemed to have equivalent speed. TheAFO60-Li36 seemed to have 1/4 grade (or less) more contrast. Both had excellent solid dark areaswith the AFO60-Li36 looking slightly more solid. The AFO40-Li24 was slightly warmer and theAFO60-Li36 was very neutral in color (although not perfectly neutral). Although both prints couldbe considered acceptable, the AFO60-Li36 had a bit more substance and depth. Portions of theimage looked more alive in the AFO60-Li36 print.

FO SERIESThese prints with the FO sensitizer and Li metal salt all showed the same speed and contrast. The


15.4

prints exhibited an interesting orangish brown color much more obvious in the FO-Li18 andFO-Li24 prints. FO-Li6 was weak and muddy and FO-Li12 was not far off from the mud. FO-Li18through FO-Li36 were fairly identical. These findings verify the DOP process equation.

FO vs AFOComparison was made with the FO-Li24, AFO40-Li24, AFO60-Li36 prints. The FO prints seemedto be a slight bit slower. The prints showed the same contrast up to about Zone VI where the AFOprints then went on to show about 1 grade more contrast. The FO prints were definitely warm incolor with the AFO prints close to neutral.. The FO prints had more solid dark areas and exhibitedmore depth and substance than the AFO40 prints. The AFO60-Li36 prints seemed to have the samedepth and substance of the FO prints; the differences being the color and the contrast in the uppervalues.

FINDINGS:

THE POP EQUATION:From the POP Process Equation it is calculated that the AFO40 should be totally used with aLi2PdCl4 solution of 24.49% indicating that an additional amount of Li2PdCl4 would be unused.In the AFO40 prints, quality increased from the Li6 to the Li24 and then was constant to Li30 andLi36. This would indicate a "point of saturation" between Li18 (18%) and Li24 (24%). Recall thatLi24 is an abbreviation and that the percentage has been rounded to 2 digits. The actual percentageof <24> to four digits was <24.49>. Li24 is the solution of 24.49%. This "point of saturation" datasupports the balance of one for one as given by the process equation.

In the AFO60 prints, print quality compared with AFO40 prints was improved in the Li30 and Li36but remained the same in Li24 and Li18. This would indicate a "point of saturation" between Li24and Li30. This AFO60 data is consistent with the AFO40 data and also supports the balance of onefor one as given by the process equation.

CONCLUSIONS

� The POP and DOP processes rely on a use of one molar equivalent of metal double salt forevery molar equivalent of sensitizer. If less metal (by way of a weaker metal solution) isused, the result is a weaker print.

� The DOP process seems to require much less metal (by way of a weaker metal solution) thanthe POP process to get desirable results.

� The POP process can achieve unique effects, such as a neutral or cool color, but seeminglyonly at the expense of using much more metal (by way of a stronger metal solution).


15.5

This study is used to set what the concentrations for the metal solutions should be for a givensensitizer solution. These can be found as the calculated formulas in the Chapter 6 section,Optimized Formulas for Metal Solutions. Further study of the amount of metal that is actuallyrequired to optimize the print quality for POP is addressed in a further study, Verification of MetalSolution Optimization.


15.6

Verification of Metal Solution Optimizationcreated August 1999, updated October 1999

An empirical study (Empirical Verification of the POP Process Equation) to determine theappropriate ratio of metal double salts to sensitizer for the POP (Printing Out Process) Pt/Pd processequation supported a ratio of one-to-one. The solution concentrations for various metal double saltsolutions were then calculated. That study produced prints which demonstrated that for givensensitizer solutions (40% and 60% Ammonium Ferric Oxalate [AFO]) certain metal solutionconcentrations existed that below which produced progressively weaker prints and above whichproduced identical prints. These metal solution concentrations corresponded to those as calculated.

A question remained as to what amount of metal would be the threshold for making the highestmetal containing print using the AFO sensitizer. The threshold being that point at which furtherincrease of metal would no longer present a perceivable improvement in the print.

For the DOP (Develop Out Process), the Ferric Oxalate (FO) sensitizer provides a limiting functionas it can only be mixed to about a 27% solution under standard conditions (25oC, 1 atmospherepressure). To date all attempts have demonstrated that the highest concentration of FO (27%) andthe respective calculated metal solutions produces the highest quality prints. If lower concentrationsare used, noticeably weaker prints are observed. It might be stated that any threshold for DOPcannot be attained due to the limit set by the maximum strength of the FO solution.

Note: With the addition of oxalic acid or EDTA, the FO solution can be mixed stronger than 27%.However, studies of the FO sensitizer have demonstrated it to achieve an optimum solutionstrength of between 24% and 26% depending on the quality of the FO powder and thesubstrate used. See the studies Threshold for FO Solutions, Comparisons of Ferric OxalatePowders, and Verification of FO Powder Composition.

For AFO, a solution strength of 60% is easily obtained. However a limit comes into play in that this60% solution with the corresponding calculated metal solution produces a coating solution whichbegins to have problems, including:

� streaks in the print from brush marks because of the thick solution;� crystallization of the coating mixture if not applied immediately after mixing;� graininess in the prints perhaps from unnoticed crystallization;� bleeding of metal from the print in the water pre-clearing bath.

Questions emerge as to what is the limiting concentration of the FO and AFO sensitizers, and doesa metal amount threshold occur within these limit. The purpose of this study is to answer thesequestions and formulate a coating recommendation for POP using AFO. Other studies, referencedabove, provide coating recommendations for DOP using FO.


15.7

The Study:Prints were made from the following coating mixtures (see end of Preparing the Coating Solutionfor a description of nomenclature used).

The AFO was a solution of 60%.The Li2PdCl4 was a solution of 36.73%.The W indicates H2O.

Coating Mixtures Use for Study

A B C D

1 6AFO60-6L36-0W

2 5AFO60-5L36-2W

3 4AFO60-4L36-4W 6AFO60-6L36-6W

4 3AFO60-3L36-6W 6AFO60-6L36-12W 4AFO60-4L36-8W

5 2AFO60-2L36-8W 6AFO60-6L36-24W 4AFO60-4L36-16W 3AFO60-3L36-15W

6 1AFO60-1L36-10W 6AFO60-6L36-60W 4AFO60-4L36-40W 3AFO60-3L36-30W

� The mixtures of the A column start at 60% (A1) and diminish in concentration through 40%(A3) to 10% (A6).

� The mixtures of the B column are diluted identical to their counter parts of the A column butkeeping an identical amount of metal as the first mixture (the calculated 60% AFO mixture).

� The mixtures of column C are diluted identical to their counter parts of the A and B columnswhile keeping an identical amount of metal as in the calculated 40% AFO mixture.

� The mixtures of column D are diluted identical to their counter parts of the A, B, and Ccolumns while keeping an identical amount of metal as in a 30% AFO mixture (A4).

� Each of these mixtures was coated into an identical area of about 25 square inches (enoughroom for a 4x5 negative a 21-step). Keeping the area of coverage constant is critical, andin order to accomplish this for some of the mixtures in the B and C columns, a differentcoating method was devised (see the Quasi Multi-Coating Method below).

The purpose of column A was to observe an incremental decrease in the concentration of coatingmixture solutions. It is important that the sensitizer to metal solution ratio remains one-to-one asthis was determined to be proper from previous study.

One purpose of columns B, C, and D was to compare the dilution of the coating mixture at valuesof 60%, 40%, and 30% AFO with the reduction of mixture (column A).

Another purpose of columns B, C, and D was to investigated changes in total metal contentindependent of mixture concentration and without problems associated with the stronger solutions.


15.8

This investigates a row such as 4, 5, or 6.

� Ambient conditions were temperature of 73-75oF, relative humidity of 65-67%.� The paper used was Crane's Parchment Business Card Stock (AKA: Cover-90; CP)� Single coatings received a very brief pre-mist; multi-coatings received no pre-mist.� All were coated by brush and "Wet" dried (see the Wet Dry Drying Study.)� All were exposed for 12 minutes under UV lamps. A6 was repeated with a longer exposure

to verify that the weakness was not from speed loss.� All were processed the same:

� 2 minutes water bath� 20 minutes total clearing in H3PO4.� Buffered rinse and 8-10 minute wash.

Observations:General Observations� Strength and Depth of image (dark values) B5 & B6 had excellent strength and depth with

good solid dark areas more so than all the others.� B3, C4, C5, & C6 had excellent strength and depth with good solid dark areas more so than

the A group but not quite as much as B5 & B6.� A2 & A3 had excellent strength and depth with good solid dark areas but not quite as much

as those above.� A4 had very good strength and depth with good solid dark areas but noticeably less than

those above� A5 was slightly weak.� D5 & D6 were definitely weak, not as weak as A6 but weaker than A5.� A6 was definitely weaker than all.� A1 & A2 were the only prints to �bleed� metal into the water (pre-clearing) bath.� A1 was not included in this comparison as some weakening was noticed likely due to other

factors.

Overall Substance and Presence� B5, B6, C4, C5, A2, & A3 showed the most Substance and Presence.� A6, D5, and D6 showed the least Substance and Presence.� B5 came the closest to matching (identical) the Substance and Presence of a DOP print.

Image Color� A1, A2, & A3 were neutral color; A4, A5, & A6 were barely slightly warmer.� B3 & B4 were neutral color; B5 & B6 were slightly warmer.� C4, C5, & C6 were in-between the neutral and warm colors with C5 the warmest.� D5 & D6 were neutral color.

Image Graininess of large tonal areas (21-step)� A1 was noticeably grainy; A2, A3, & A4 slightly grainy; A5 & A6 were smooth.


15.9

� B3 was slightly grainy; B4 barely showed some grain; B5 & B6 were smooth.� C4 barely showed some grain; C5 & C6 were smooth.� D5 & D6 were smooth.

Paper Surface� The surface of B6 was slightly rougher (probably due to the long brushing of five coats).� The surfaces of those receiving three or four coats (B5, C6, & D6) felt barely, but noticeably,

rougher.

Speed� All the coatings seemed to be close to the same speed. Too close to be evaluated by the

21-step, however a few appeared slightly darker throughout the print (B5, B6, & C5).

Contrast� A1 through A6 showed a graduated change in contrast with A6 being about 1 grade more

contrast.� The B group showed the same gradation of contrast with B6 being the highest but about a

half grade less than A6.� The trend followed in the C and D groups (6 the most contrast); and in each row, A having

the most contrast. In all rows the contrast progressively changed about one and a halfgrades.

� Two coats by the Quasi Multi-Coating Method consistently produced a half grade lesscontrast than a single coat.

Quasi Multi-Coating MethodThis author has had mixed results from multiple coatings in the past. A thought was that some ofthe past difficulties could have been related to drying the mixture and then re-coating. Coatings ofmixtures containing 50 % to 100 % additional mixture had been brushed into the same areas withoutproblems. So it was supposed that additional mixture could be added to the coating before it driedcompletely. (Hence the term Quasi.)

The Quasi Multi-Coating Method is basically as follows:

� Pour out a typical amount of mixture on to the paper as with a single coating;� Brush this into the area desired as if it were a single coating;� Allow to dry beyond the point of loss of gloss, but before complete dryness (rather damp);� Pour out some more of the mixture (about the same amount);� Brush this into the area desired as if it were a single coating;� Allow to dry beyond the point of loss of gloss, but before complete dryness (rather damp);� Continue until all of the mixture is used.� Dry to desired dryness.

Each pouring should be enough to completely coat a layer over the full area. Do not extend any


15.10

mixture beyond this area. With this Quasi Multi-Coating Method, it is of the utmost importance thatthe coating be restricted to the correct area and completely fill the area each partial coating.Spreading the mixture too thin (past the area) will result in a weakened coating which, if at thethreshold, will produce a weakened print. Not spreading the mixture to fully to cover the area willresult in a stronger coating in some places and may produce non-uniformities in the final print.

The coating of mixture B6 was accomplished with five pourings (5 quasi coats) and took a littlemore than half an hour to coat and dry. These coatings produced excellent prints. All of the Agroup had one coat; B5 had three coats; B4 two coats; B3 one coat; C6 four coats; C5 two coats; C4one coat; D6 three coats; D5 one coat. Drying times are significantly lengthened with multiplecoats.

A few of the coatings showed some difficulty (large lighter blotchy areas) which was likely becauseof too much drying of the first coating. Those coatings were repeated, taking care not to over dry,and produced excellent results. It was also noted that none of the prints (including the 5 coat)showed any signs of solarization effect.

Discussions

COVERAGE:Consistency of the coating coverage is of critical importance. Coverage is expressed as cm2/ml anddefined as:

[Coverage] = [area of coating in cm2] /[number of drops of sensitizer at specified solution concentration] * [ml per drop]

An increase in coverage will weaken the print, and a decrease in coverage will waste chemistry.Because multiple coatings may be made and may use a diluted mixture, the total number of mixturedrops is not an accurate reference. The appropriate reference is the number of drops of sensitizersolution, which is identical to the number of drops of metal solution. The purpose of coating is toget a known amount of active chemicals evenly distributed throughout the coated area. Coverageindicates that amount.

Coverage will vary by paper and must be determined for each paper. Knowing the coverages willpermit the easy transition from one paper to another without the worry of insufficient chemistry.The Coverage for the paper used in this study is calculated as follows.

Coverage of CP = 161 / 6 * 0.05 = 1.34 cm2/ml

This means that an 8x10 with half inch boarders (100 inches2 or 645 cm2) will require the numberof drops of sensitizer as follows.

drops = [area coated] / [Coverage] * [ml per drop] = 645 / 1.34 * 0.05 = 24


15.11

Add to this amount of sensitizer, an identical number of drops of the appropriate metal solution(s),an optional drop of contrast agent, and any optional dilution water, to make a coating mixture foran 8x10 on CP.

THRESHOLD:Column A alone indicates that A4 (a 40% AFO solution with respective metal solution) may beclose to the threshold.

When evaluating the rows, it is noticed that column D (a 30% AFO solution with respective metalsolution) is far below the quality of column C (a 40% AFO solution with respective metal solution)

Columns B (a 60% AFO solution with respective metal solution) and C (a 40% AFO solution withrespective metal solution) are very close. In row 6, B is definitely better than C. In rows 4 and 5the prints look identical with B5 being a bit warmer.

It is suspected that the appearance of depth and substance may be enhanced by a slight warm color.Without this color B5 and C5 would look identical.

Without finer tuning, it is most likely that the 40% AFO solution with respective metal solution isthe closest to the threshold (30% being definitely too weak). It is possible that slightly less than40% may be used and should be verified.

QUASI MULTI-COATING:It appears that multiple coatings by the method above may produce a fuller advantage of thematerials than a single coat. C5 appears superior to C4 and A3 (especially considering smoothness).

Two coats by the Quasi Multi-Coating Method consistently produced a half grade less contrast thana single coat. However, further coats showed an increase in contrast, suspected to be caused by anoverriding influence of dilution.

Further Data and DiscussionAdditional data was sought from coatings based on a 35% AFO solution with respective metalsolution. To accomplish this two prints were made with the following coating mixtures.

� 12 drops of the mixture 7AFO60-7L36-10W� 24 drops of the mixture 7AFO60-7L36-36W

Note: For reference 7AFO60-7L36-10W is the equivalent of 12AFO35-12L21 which istwice the amount needed for the area coated.

The prints fit into the above assembly of prints where expected. These prints were extremely close


15.12

to C4, C5, and A3. They were noticeably better than D5 and D6 and slightly better than A4.

These prints appear to be of a quality good enough to consider them closer to the threshold thanthose of the 40% AFO.

These prints had a neutral color and did not appear to have as much depth or substance as B5 andB6. However, it is becoming more convincing that the depth and substance perceived is a functionof other than only the amount of metal in the print (i.e., the color has some influence).

Conclusions and Recommendations

A reminder that this information is paper specific. The sensitizer solution strength (and theassociated metal solution) and coating mixtures for other papers should be evaluated by this or asimilar procedure. However, the ratio of sensitizer to metal solution will remain unchanged.

It is unlikely that a change to another type of metal solution will influence these results, if that metalsolution is the calculated optimized solution for the solution of sensitizer (see Optimized Formulas).

For POP, a 35% AFO solution with respective metal solution provides enough metal to reach thediscussed threshold and should be the coating mixture used and applied as either a single coat or atwo coat Quasi Multi-Coating.

This translates to the following coating solutions and equivalent coating mixture recommendation.

AFO made as a 35% solution (AFO35).Li2PdCl4 made as a 21.43% solution (L21).Na2PdCl4 made as a 24.05% solution.K2PdCl4 made as a 26.7% solution.K2PtCl4 made as a 33.9% solution.

Note: Metal solutions may be mixed or interchanged freely.

For single coat:(#drops) (AFO) - (#drops) (metal solution)[ - 1 drop (contrast agent)] optional

For double Quasi Multi-Coating:(#drops) (AFO) - (#drops) (metal solution) - (2 times #drops) (H2O)[ - 1 drop (contrastagent)] optional

An advantage of the double Quasi Multi-Coating:As some of the metal solutions above will not stay in solution (unless heated), they could be mixedat half their concentration, twice the #drops put into the mixture, and a #drops deleted from the H2O.


15.13

For double Quasi Multi-Coating with metal solutions at half their strength:(#drops) (AFO) - (2 times #drops) (metal solution) - (#drops) (H2O)[ - 1 drop (contrastagent)] optional

Additional PonderingNot only has this study been paper dependent, results are also affected by coating efficiency. TheWet Dry Drying Study has roughly predicted a coating efficiency of 81% for the brushingtechniques used. A different brushing technique or the use of a rod may have a different coatingefficiency. A higher efficiency would allow the solution strengths to be reduced, and a lowerefficiency would require the solution strengths be increased. It is highly recommended that astandardized coating technique be practiced and used at all times.

An important aspect of this study has been to determine and to have technique to consistently putthe maximum beneficial (threshold) amount of metal into the coating.


15.14

Wet Dry Drying Studycreated August 1999

The purpose of this study was to investigate any differences that may have existed between exposinga coating that has been dried �Wet� or �Dry�.

Drying "Wet" means that the relative humidity (RH) of the coating was at ambient and relativelyhigh (typically 60-70% RH) when exposed. Drying is accomplished by blowing ambient air overthe coating until just dry and letting RH of the coating come to that of the ambient.

Drying "Dry" means that the ambient RH was relatively low (preferably less than 40% RH) and theprint dried by blowing air with medium heat over the coating to dry as much as possible. Thismethod is that which is also referred to as drying to �bone dry�. The dried coating is quickly putin the contact frame and exposed so as to keep driest.

Note: A method to check if the RH of a paper has reached equilibrium with the ambient, is to placethe paper on a scale accurate to 0.01 grams and observe the movement. An increase willindicate an increasing RH in the paper; while a decrease will indicate a decreasing RH in thepaper.

This study was made after preliminary work from other studies and early on demonstrated someinteresting results.

� It became apparent that the paper may change water content rather quickly.� Solarization effects may occur - which are addressed later.� A printout which was unusually very dark and of extremely high contrast was only

seen with the �wet� dried coatings at an ambient temperature of 82oF. However, thishigh of a temperature produced its own problem as discussed in Solarization later.

� Pre-humidification of the paper had to be re-thought and is also discussed later inSolarization.

� As a result of preliminary study, the �Dry� portion needs to be repeated.

All weights were measured with an Ohaus Cent-O-Gram mechanical quad balance scale accurateto 0.01 grams.

Ambient ConditionsFor the �Wet� part, the temperature was 72oF and the relative humidity 62%RH for A, B, C, and D;and the temperature was 75oF and the relative humidity 68%RH for E.

For the initial �Dry� part, the temperature was 77oF and the relative humidity 45%RH for A, B, C,and D. Plans are to repeat the �Dry� portion keeping the RH below 40%.


15.15

Materials and Procedure� Paper was Crane's lot # 5302 (AKA parchment Business card stock, Cover 90,

�platinotype�). Paper was cut to slightly larger than area to be coated.� This paper was chosen as it is a thick paper having a capacity to hold moisture.� Coating was 9 drops FO (27% solution), 6 drops K2PdCl4(19% solution), 3 drops K2PtCl4

(24% solution), 1 drop Ammonium Dichromate (0.25% solution).� This coating mixture is typically used.� Coating mixture was weighed.� Paper was weighed.� Paper was humidified only briefly on the coating side with a sonic mister. (See discussion

of Solarization later.)� Paper was weighed and verified that there was no increase in weight. (See discussion of

Solarization later.)� Coatings were applied by brush and covered enough area for a 4x5, and a 21-step.� Coated paper was weighed.� Coatings were dried by one of the methods above.� Dried coated paper was weighed.� Coating exposed for 10 minutes with BL type lamps through a negative and 21-step.� Exposed paper weighed.� Developed in Potassium Oxalate (1 minute)� Rinse/Pre-clear in water bath (2 minutes)� Cleared with phosphoric acid baths for a total of 30 minutes� Rinsed in buffered water, washed, dried� Dried, finished print weighed.

Weighing Data

Drying �Wet� - weight in grams

A B C D E

mixture weight 1.25 1.25 1.25 1.25 1.25

pre-misting 4.91 4.76 4.46 4.15 6.08

pre-coating 4.91 4.76 4.46 4.15 7.01

post-coating 5.93 5.82 5.47 5.12 7.08

post-drying 5.25 5.02 4.72 4.44 6.34

post-exposure 5.01 4.68 4.39

final 5.00 4.86 4.55 4.28 6.04


15.16

Drying �Dry� - weight in grams - Data questionable due to Pre-misting

A B C D

mixture weight 1.25 1.25 1.25 1.25

pre-misting 9.26 8.73 8.71 8.71

pre-coating 9.39 9.12 9.08 9.39

post-coating 10.24 10.00 9.92 10.29

post-drying 9.04 8.75 8.72 8.92

post-exposure 9.10 8.75 8.76 8.98

final

"Dry" data will be obtained in which the pre-misting is omitted or reduced so that no gain in weightis detected, with the RH kept below 40%.

Calculations:Drying �Wet� - changes of weight in grams

A B C D E

Due to misting 0.00 0.00 0.00 0.00 0.03

Due to coating 1.02 1.06 1.01 0.97 1.01

Start to Dry 0.34 0.26 0.26 0.29 0.26

Due to exposure -0.01 -0.04 -0.05

Start to final 0.09 0.10 0.09 0.13

Drying �Dry� - changes of weight in grams - Data questionable due to Pre-misting

A B C D

Due to misting 0.13 0.39 0.37 0.50

Due to coating 0.85 0.88 0.84 0.90

Start to Dry -.22 0.02 0.01 0.03

Due to exposure 0.06 0.05 0.04 0.06

Start to final


15.17

The weight of the coating chemistry minus water except for the 6H2O attached to the FO iscalculated to be about 0.0203 grams assuming none lost.

Observations

SOLARIZATION� "Wet" prints A and B showed no solarization.� "Wet" print D barely showed a minute solarization.� "Wet" print C showed very little solarization.� "Wet" print E showed some solarization. The RH of E was intentionally forced upwards;� "Dry" prints that received a strong pre-coating misting showed solarization.

Note: "Dry" prints will be repeated without a weight gain from pre-coating misting.

In every example the solarization did not show while the prints were wet from processing; only afterdrying did the solarization become apparent. This hiding of the solarization is suspected to berelated to the depth that the coating has penetrated the paper; when wet, greater depth is viewed intothe paper. (This is also why prints appear to have greater depth and substance when wet.)

Whether what is happening is actually solarization is not known. What had been observed, and nowrelated to certain conditions, appears similar to a solarization. What is important is that this effectcan be avoided or significantly reduced by controlling a couple of the parameters. It is expectedthat different papers will behave differently, so the conditions set forward in this study only applyto the paper used.

Previous experimentation demonstrated that the solarization effect was only observed at higherambient temperatures (82oF) and when the pre-coating misting was overabundant. When theambient temperature was kept lower than 75oF and care was given so as to only just barely mist thepaper prior to coating, no or very little solarization was observed. All other parameters had beenkept constant.

It has been known for some time that papers generally coat better when cold, and that more mixtureis required to coat the same area at a higher temperature. It is suspected that the higher temperatureencourages the chemistry to soak deeper into the paper. This is paper dependent; and is much morenoticeable in a thicker paper which absorbs moisture.

It has been thought that pre-coating humidification of most papers was beneficial as it made thepaper more susceptible to accepting the coating. However, this must now be re-thought, as too muchhumidification (misting) may now promote this solarization effect. It is suspected that a rise inrelative humidity above the ambient will encourage the coating chemistry to soak too deeply intothe paper. At a temperature of 73oF, an over misted paper led to solarization, whereas no mistingprovided an excellent print with no signs of solarization.


15.18

The solarization effect is suspected to be caused by the deep absorption of coating chemistry intothe paper. It is desirable to get the chemistry into the paper, but it appears now to a certain limit.This limit can be controlled by a joint effort of command over the temperature and the pre-coatingmisting. Each paper will have its own characteristics. For the Crane paper used in this study, it issuggested that the ambient temperature be kept below 75oF. For any paper it is suggested that themisting be quick enough to not increase the weight of the paper (measured to at least 0.01 grams).

PRINTOUTAnother effect of the higher temperature was a dramatically increased printout. This printout wasextremely high contrast and dark. It is thought the this printout would produce a better separationof shadow detail. This increased shadow detail was observed in some prints, however these printsalso exhibited a large amount of the solarization effect. It would now become a balance of shadowdetail versus solarization. It does seem that the solarization could be controlled to the very darkestareas while the increased shadow separation could result in an overall benefit to the print. This wasnot attempted for this study; the temperature was kept in the low to mid seventies and all tests keptmisting to a minimum so as to not cause an increase in weight. This printout may have merit andshould be studied further.

PRINT COMPARISONSTo be completed after obtaining "Dry" data.It is suspected that prints will be almost identical, but more data must be collected to verify this.And, this is expected to be paper dependent.

WEIGHT COMPARISONSTo be completed after obtaining "Dry" data.A weight of interest here is the start-to-finish which is expected to give an indication of thedifference in water content between the "Wet" and "Dry" methods. If it is assumed the the "Dry"method produces no weight increase, the amount of water in the "Wet" method, for the givenambient conditions, would average 0.28 grams. Plans are to obtain this weight for several ambientRH, and determine the temperature sensitivity, IF... If there is a notable change observed in theprint. Thus far it is suspected that prints will be almost identical.

CHEMISTRY CONSUMPTIONConsidering "Wet" prints only.Note that not all of the coating chemistry was delivered to the paper as some was soaked up by thebrush and some stuck to the shot glass. If it is assumed that the chemistry delivered to the paper is(weight of post-coat)-(weight of pre-coat) or delta due to coat, this would indicated that a bit morethan 81% of the chemistry was delivered to the paper.

Conclusions:Temperature and pre-coat misting can be controlled so that the solarization effect can be avoidedor minimized.To be completed after obtaining "Dry" data.


15.19

Chapter 15c - StudiesInitial Threshold Study for FO solutionscreated October 1999, updated April 2005

This study centers on determining what amount of metal would be the threshold for making thehighest metal containing print using the Ferric Oxalate (FO) sensitizer. The threshold being thatpoint at which further increase of metal would no longer present a perceivable improvement in theprint.

The threshold is dependent on many factors including the paper selected, the area coated, the coatingprocedure and coating efficiency. It is imperative that the coating coverage and area be determinedand the coating mixture be restricted to the area.

Note: Pencil lines are a helpful way to delineate the area.

If one desires more flexibility and less restrictive accuracy, solution concentrations may be usedwhich are higher than the threshold. This may accommodate various papers, inaccuracies inefficiency, coverage, or areas, and some inconsistencies in coating procedure. This convenience willbe traded for the cost of some unused metal and sensitizer. Using less material than required to meetthe threshold will result in a noticeably weaker print.

The StudyThe sensitizer was initially mixed as a 30% solution.

7.65 grams Vizcay FO powder (estimated to contain 0.15g Oxalic Acid & 7.50g FO)1.00 gram EDTA (Na4)0.80 gram Oxalic AcidH2O to make final volume of 25.0 ml when completely dissolved

The drop sizes of all the solutions were determined to be 0.05 ml/drop.A bulk base coating mixture was mixed consisting of:

70 drops sensitizer (described above) (30 % solution)50 drops K2PdCl4 solution (20.2 % solution, warmed)20 drops K2PtCl4 solution (25.7 % solution, warmed)

Both metal solutions must be warmed to keep dissolved. These are the metal solution concentrationsfor use with a 30% solution of Ferric oxalate. The Metal Solution Formula Calculator may be usedto determine the metal solution formulas to use with other sensitizer and concentrations.


15.20

Prints were made from the following coating mixtures based on the following sensitizerconcentrations.

M = bulk base coating MixtureW = H2O

# of drops mixture equivalent %concentration of sensitizer

15 15M 30 %

15 14M+1W 28 %

15 18M+2W 27 %

15 13M+2W 26 %

15 15M+3W 25 %

15 16M+4W 24 %

15 11M+4W 22 %

15 10M+5W 20 %

� Ambient conditions were temperature of 68-70oF, relative humidity of 34%.� The paper used was Crane's Parchment Business Card Stock (AKA: Cover-90; CP)� Coatings were by brush into an area 5 inches by 5 inches (25 inches2 or 161 cm2)� All were dried by the dry method (see Drying the Coating).� All were exposed with the same negative and a 21-step for 10.25 minutes under UV lamps.� All were processed the same:

� developed in Potassium Oxalate� 2 minutes water bath� 30 minutes total clearing in H3PO4 (3 baths).� Buffered rinse and 10 minute wash.

ObservationsNote: When discussing results, the #% refers to prints make with the equivalent % concentration

of sensitizer solution and associated metal solution.

� The 20% was noticeably slightly weaker and showed a very slight solarization effect.� The darkest areas of the 22% and 24% (as well as the 20%) were not solid (having a "pin

holes" sort of look when viewed with transmitted light), and the 25% had a slight hint of thiseffect, unlike the other prints which were uniformly very solid.

� The prints were identical other than the above differences.


15.21

All of the prints made from a mixture at or above 26% FO in the sensitizer and with thecorresponding metal solution were identical by any visual observation. All of the prints below the26% had some lesser quality observed.

Conclusions and RecommendationsIt is concluded that for the materials and conditions used, a threshold of 26% is to be expected.Another paper may have a different threshold.

It is recommended that, for the materials and conditions as above, a sensitizer solution with a FerricOxalate concentration of 26% be used, along with the respective concentrations of metal solutions.The metal solutions for a given sensitizer may be found using the Metal Solution Formula Calculatoror from the tables in Chapter 6, Optimized Formulas for Metal Solutions.

It is alright if a FO concentration slightly greater than 26% is used and may provide some greaterflexibility and diversity. However, it must be remembered that at higher concentrations, it canbecome more difficult to dissolve the metal solutions.

These recommendations are being verified and may change.


15.22

Initial Comparisons of Ferric Oxalate PowdersOctober 1999, updated April 2005

Several FO powders were compared by measuring specific gravity and pH to investigate anysimilarities or differences. Some differences were noticed immediately upon the preparation of thesolutions and subsequent work attempted to find a reason for those differences. (Note: Laterconclusions and study indicate that evaluating prints made from the solutions provided a betterunderstanding than the specific gravity and pH measurements.)

The PowdersComparisons were made of Ferric Oxalate (FO) powder from the following sources.

� Bostic & Sullivan (B&S), commercial supplier� Vicente-M. Vizcay Castro (Vizcay), made by Vicente-M. Vizcay Castro following his

preparation procedure� Jeffrey D. Mathias (JDM), made following Vizcay's preparation procedure

The SolutionsSolutions were made from the above Ferric Oxalate (FO) powders as described.

Preliminary SolutionsInitially the B&S and Vizcay solutions were mixed as 16.20 grams FO and 48.0 ml H2O.The solutions were shaken intermittently for 24 hours. Due to the large amount ofundissolved FO another 2.0 ml H2O was added. After another 24 hours of intermittentshaking another 1.0 ml H2O was added. It did not seem that the solutions would completelydissolve so they were shaken well and poured into a graduated cylinder and another 1.5 mlof H2O was added to bring the total volumes to 60.0 ml (at 78oF). These solutions are whatthis study refers to as the �Preliminary Solutions�.

It was noted that the Vizcay solution had what appeared to be about 4 times the undissolvedFO as did the B&S solution at a point were solubility equilibrium was expected.

If these solutions had dissolved completely, they would have been 27% solutions.

These solutions were heated slightly, shaken well and immediately divided into two 30 mlamounts.

For each FO type, one of the 30 ml portions (Preliminary Solution) had the Specific Gravity(SG) and pH measured.


15.23

It was felt that Oxalic Acid may be necessary for complete dissolving. For each FO type, theremaining 30 ml portion had Oxalic Acid added at small intervals until complete dissolving and thenwere termed the "Oxalic Solutions".

Oxalic Solutions:To these solutions (30 ml portions from above), Oxalic Acid was added in an amount of0.10 gram at a time with shaking and waiting a day or two for dissolving.

The B&S and Vizcay Preliminary Solutions (27%) were found to dissolve completely (at70oF) when the following amounts of Oxalic Acid were added to the 30 ml of solution.

B&S 0.50 gVizcay 1.40 g

These solutions are what this study refers to as the �Oxalic Solutions�. The Specific Gravity(SG) and pH were measured.

Straight Solutions:The remainder of the Preliminary Solutions after testing was 23.0 ml. To this 0.50 ml ofH2O was added and shaken intermittently for 24 hours. The solutions were still notcompletely dissolved so another 0.50 ml H2O was added and shaken intermittently for 24hours. At this point both FO appeared to be completely dissolved at a temperature of 70oF.These solutions had a concentration between 26.4% (not dissolved) and 25.9% (completelydissolved).

These solutions are what this study refers to as the "Straight Solutions". The SpecificGravity (SG) and pH were measured.

EDTA solutionsJohn Melanson had claimed that EDTA (Na4) would allow the ferric oxalate solution toattain a higher concentration. 8 grams of ferric oxalate powder plus 1 gram of EDTA (Na4)had H2O added in small increments until the material was completely dissolved at atemperature of 70oF (allowing at least 24 hours of intermittent shaking). The total H2Oadded was 22 ml; the total volume of the solution was about 25ml. These were 32%solutions.

These solutions are what this study refers to as the "EDTA Solutions". The Specific Gravity(SG) and pH were measured.

Balanced SolutionsWith the intention of maximizing the ability to accurately compare powders and investigatethe solubility difference when adding oxalic acid, �Balanced Solutions� were made from the


15.24

powders. To accomplish this, the amount of oxalic acid assumed in each FO powder wasestimated as discussed below in Estimated Contents of Powders. An addition of 4% EDTA(Na4) was also used so as to achieve FO concentrations of 30%.

8.45 grams B&S FO powder (assumed to contain 0.91 gram Oxalic Acid & 7.54 grams FO) 1.00 gram EDTA (Na4) 0.04 gram Oxalic Acid H2O to make final volume of 25.12 ml

7.65 grams Vizcay FO powder (assumed to contain 0.15 gram Oxalic Acid & 7.50 grams FO) 1.00 gram EDTA (Na4) 0.80 gram Oxalic Acid H2O to make final volume of 25.0 ml

7.65 grams JDM FO powder (assumed to contain 0.15 gram Oxalic Acid & 7.50 grams FO) 1.00 gram EDTA (Na4) 0.80 gram Oxalic Acid H2O to make final volume of 25.0 ml

These solutions are what this study refers to as the "Balanced Solutions". The SpecificGravity (SG) and pH were measured.

Summary of SolutionsPreliminary Solutions 16.20 grams Ferric Oxalate powder, plus 52.5 ml H2O

Shaken well immediately before measuring (not dissolved,but assumed homogeneous).

Oxalic Solutions 16.20 grams Ferric Oxalate powder, plus 52.5 ml H2O,plus amount of Oxalic Acid needed to completely dissolve.

Straight Solutions 25.9 % solutions (FO powder only, no additional OxalicAcid, assumes 100% pure FO), Completely dissolved.

EDTA Solutions 8.00 grams Ferric Oxalate powder, plus 1.00 gram EDTA(Na4), plus 22 ml H2O, Completely dissolved.

Balanced Solutions 30% solution of Ferric Oxalate using estimated contents ofpowders, plus 1.00 gram EDTA (Na4), plus amount of OxalicAcid needed to provide identical minimum amounts in allsolutions, plus H2O to make 25 ml when completelydissolved.

Estimated Contents of PowdersIt might be assumed that the powders consist only of Ferric Oxalate and Oxalic Acid. Theseare the only materials introduced in the Vizcay procedure, and these are the only ingredientsclaimed by Bostic & Sullivan in their product. Trace amounts of Nitric Acid (detected by


15.25

odor) and water are likely but assumed negligible.

The initial Oxalic Acid contained in the Vizcay powder can be estimated as follows. TheVizcay preparation provides an additional 2.5% Oxalic Acid. If it is assumed that all of thisadditional Oxalic Acid remains unreacted, the Vizcay powder can be assumed to contain:

1.92% Oxalic Acid by weight;98.08% Ferric Oxalate by weight.

It follows that: (% Oxalic Acid in powder) = (extra Oxalic Acid)/(powder produced whichincludes FO and the extra Oxalic Acid) or0.0192 = (117 * 0.025) / (149.7 + (117 * 0.025))

If one assumes that a certain amount of Oxalic Acid is responsible for the ability tocompletely dissolve the FO powders at a certain concentration (see preparation of OxalicSolutions), then it is possible to estimate the amount of oxalic acid in the batch of B&Spowder.

For this estimate let:B represent the solution made with B&S powderV represent the solution made with Vizcay powderF represent weight of ferric oxalateO represent weight of oxalic acid included with the powderA represent weight of oxalic acid in addition to what was in the powder

The weight of powders used to make the Oxalic Solutions was identical, thus:

FB+OB = FV+OV

From the assumption above, the ratio of the total amount of oxalic acid to ferric oxalate ineach solution is identical when the solutions have just the right amount of oxalic acid addedto achieve a completely dissolved solution at a given temperature. This is represented as:

(AB+OB) / FB = (AV+OV) / FV

What is desired is the amount of oxalic acid that would need to be contained in the B&Spowder (OB) in order to equate with the amounts of oxalic acid added to achieve completesolubility. The following are known from the Oxalic Solutions and the calculationconcerning the Vizcay powder above:

FB+OB = FV+OV = 8.10 grams AB = 0.50 gram

OV = 0.156 gram AV = 1.40 grams

FV = 7.944 grams

OB is calculated from (derivation of equation):


15.26

OB = (FV * (AV+OV) + OV * (AV+OV) - AB * FV) / (FV+AV+OV)OB = (7.944*(1.40+.156)+.156*(1.40+.156)-.50*7.944) / (7.944+1.40+.156)OB = 0.91 gram

However, note that the percentages may vary as 0.1 gram of oxalic acid was added at a timefor the determination of the Oxalic Solutions. The material had not dissolved with AB =0.40 and AV = 1.30

OB (low) = (7.944*(1.30+.156)+.156*(1.30+.156)-.50*7.944) / (7.944+1.30+.156)OB (low) = 0.83giving 10.3% Oxalic AcidOB (high) = (7.944*(1.40+.156)+.156*(1.40+.156)-.40*7.944) / (7.944+1.40+.156)OB (high) = 0.99giving 12.2% Oxalic Acid

This means that the batch of B&S powder might be assumed to contain:10% to 12% Oxalic Acid by weight;90% to 88% Ferric Oxalate by weight.

Measurements

Specific Gravity (SG) of Ferric Oxalate Solutions

Equipment:

� balance scale accurate to 0.01 grams� beaker filled with water (large enough to completely submerge the small sample

bottle)� thin wire� counter weight to zero scale (as needed)� sample bottle with cap (small enough to be completely submerged in the water in the

beaker)

The sample bottle is filled completely so that there is no air trapped inside.

If the bottle filled with water does not sink in water, then attach a �sinker� (lead) to the bottle forall measurements and consider this part of the bottle weight (the affect is a denser bottle, negativebuoyancy).

The thin wire is tied to the sample bottle with the other end looped over the scale hook.

The wire is marked at the level of the water in the beaker when the sample bottle is completely


15.27

submerged and not in contact with the beaker. The wire above the mark is considered to contributepart of the tare weight along with the counter weight. The wire below the mark is considered to bepart of the sample bottle.

Procedure

� A) The sample bottle is weighed� B) The sample bottle is filled with water and weighed submerged in the beaker with water� C) The sample bottle is filled with a solution and weighed� D) The sample bottle still filled with the solution is weighed submerged in the beaker with

water� The Specific Gravity is calculated as: SG = (C-A) / [ (C-A)-(D-B) ]

Measured Data and Calculated Specific Gravity (SG) (at 64oF)[Measurement Accuracy of 0.01 gram]

Sample Weight ofEmpty bottle

(grams)

Weight inAIR

(grams)C

Weight inWATER(grams)

D

SG(C-A) / [

(C-A)-(D-B)]

[Error of +-1.2%]

bottle 6.60 (A) 11.69 3.60 (B)

PreliminarySolutions

B&S 12.46 4.45 1.17

Vizcay 12.43 4.61 1.21

OxalicSolutions

B&S 12.51 4.42 1.16

Vizcay 12.59 4.47 1.17

StraightSolutions

B&S 12.44 4.35 1.15

Vizcay 12.48 4.38 1.15

EDTASolutions

Vizcay 12.74 4.58 1.19

BalancedSolutions

B&S 12.79 4.58 1.19

Vizcay 12.72 4.61 1.20

JDM 12.59 4.50 1.18


15.28

Specific Gravity Results:Specific Gravity of Solutions (Error of +- 2%) (temperature of 64oF)

B&S Vizcay JDM

Preliminary solutions 1.17 1.21

Oxalic Solutions 1.16 1.17

Straight Solutions 1.15 1.15

EDTA solutions 1.19

Balanced Solutions 1.19 1.20 1.18

Conversion of Specific Gravity into a Solution Concentration Percentage for FO

Page 58 of Dick Stevens' book, "Making Kallitypes" presents an abacus which relates thepercent concentration of Ferric Oxalate solutions and specific gravity. From this abacus, thefollowing formula is derived.

% = 157.89474(d-1) (d = specific gravity)Note that the Error is large due to the small volume used to measure the specific gravity.

% Concentration of Solutions Calculated from the Specific Gravity

(Error of +- 7.9%)

% concentrationof solutions as made

B&S Vizcay JDM All solutions



Straight Solutions 23.7 23.7 25.9

EDTA solutions 30.0 32.0

Balanced Solutions 30.0 31.6 28.4 30.0


15.29

pH of Ferric Oxalate Solutions

Equipment:

� pH meter accurate to 0.1 pH with automatic temperature compensation and calibration.� Shot glasses. (Unless probe fits into bottle.)

pH Results: pH reference 7.01 measured as 7.0 pH reference 4.01 measured as 4.0

pH of Solutions

B&S Vizcay JDM



Straight Solutions 0.7 1.0

EDTA solutions 0.8

Balanced Solutions 0.4 0.6 0.5

Print comparisons:Prints were made from all but the preliminary solutions. See Comparing Prints from Ferric OxalatePowders.


15.30

Verification of FO Powder Compositioncreated October 1999

In order to achieve accuracy and consistency, it is important to begin with an accurately formulatedsensitizer to which the metal solution will be balanced. The active Ferric Oxalate content needs tobe determined. The Comparison of FO Powders Study demonstrated that FO Powders may not allcontain the same amount of or 100% ferric oxalate. That study estimated the contents of some FOpowders. The purpose of this study is to verify or develop a better estimate for the ferric oxalatecomposition of those powders.

FO Powder % ferric oxalate by weight, estimated (fromComparison of FO Powders)

Vizcay 98 %

Bostic & Sullivan 89 %

Dick Stevens, in his book "Making Kallitypes", presents a method to relate the percent concentrationof Ferric Oxalate (FO) solutions with their specific gravity. From this method, the followingformula is derived.

% = 157.89474 * (SG-1)

where: % = percent concentration of FO solutionSG = specific gravity

Expected AccuracyIn order to achieve enough accuracy, a large enough volume of sensitizer must have its specificgravity measured. The 71 ml of solution measured in this study with dry chemicals weighed at anaccuracy of 0.01 grams resulted in a measured Specific Gravity accuracy of +-0.4% and a calculatedpercent concentration accuracy of +-3%. This would mean that a calculated percent concentrationof 27.0% could range from about 26.2% to 27.8% (or about 26% to 28%). Any conclusions mustconsider this range of error, and caution should be exercised whenever differences fall within theerror range.26%

Sample preparationSince the Vizcay FO powder has demonstrated the highest content of ferric oxalate, it was selectedfor this study. Several sensitizer solutions were mixed and measured at the following estimatedconcentrations. The concentrations were centered around an estimated 26-27% as per the findingsof the FO Threshold Study.

The first solution in the following table was mixed and measured; then EDTA was added and the


15.31

solution measured again; then Oxalic Acid was added and the solution measured again; then moreOxalic Acid was added and the solution measured again. These steps were to isolate influences ofthe specific gravity measurement by the Oxalic Acid and EDTA. Next the concentration of the FOis increased incrementally by adding FO powder and measured as indicated in the following table.The slight increase in Oxalic Acid from the powder added should be considered negligible.

Sample gramsVizcayFOpowder

gramsFOpowderadded toprevioussample

total gramsEDTA (Na4)

(% concentration)

total gramsOxalic Acid[including contents ofthe FO pow der, asabove](% concentration oftotal Oxalic Acid)

gramsOxalicAcidadded toprevioussample

amountin mlafter dissolvingby adding H2O

estimatedFOconcentration(from contentlisted above)

A 17.37 0.00 0.00(0%)

0.33(.47%)

0.00 71 24%

B 18.10 0.73 0.00(0%)

0.33(.47%)

0.00 71 25%

C 18.10 0.00 2.13(3.0%)

0.33(.47%)

0.00 71 25%

D 18.10 0.00 2.13(3.0%)

1.07(1.5%)

0.74 71 25%

E 18.10 0.00 2.13(3.0%)

1.78(2.5%)

0.71 71 25%

F 18.10 0.00 2.13(3.0%)

2.49(3.5%)

0.71 71 25%

G 18.82 0.72 2.13(3.0%)

2.52(3.5%)

0.014 71 26%

H 19.54 0.72 2.13(3.0%)

2.53(3.6%)

0.014 71 27%

I 20.27 0.73 2.13(3.0%)

2.55(3.6%)

0.014 71 28%

J 20.99 0.72 2.13(3.0%)

2.56(3.6%)

0.014 71 29%

Notes: Extra solution was prepared so as to be available to top off contents of the sample bottle assome losses would occur on capping and opening. No record was kept of any losses ordisplacement of solution due to the addition of solids. The initial mixture (A) required 63.2ml H2O to make the 71 ml sample bottle volume.


15.32

The addition of EDTA and / or Oxalic Acid is important as the pure FO will typically onlyattain a concentration of less than 26% with typical lab temperature and pressure.

Measurement of Specific Gravity (SG)

Equipment:� balance scale accurate to 0.01 grams� container filled with water (large enough to completely submerge the sample bottle)� thin wire� counter weight to zero scale (as needed)� sample bottle with cap (small enough to be completely submerged in the water container

without touching the container).

Preparation:� The sample bottle is filled completely so that there is no air trapped inside.� If the bottle filled with water does not sink in water, then attach a �sinker� (lead) to the bottle

for all measurements and consider this part of the bottle weight (the affect is a denser bottle,negative buoyancy).

� The thin wire is tied to the sample bottle with the other end looped over the scale hook.� The wire is marked at the level of the water in the container when the sample bottle is

completely submerged and not in contact with the container. The wire above the mark isconsidered to contribute part of the tare weight along with the counter weight. The wirebelow the mark is considered to be part of the sample bottle.

Procedure� A) The sample bottle is weighed� B) The sample bottle is filled with water and weighed submerged in the container of water� C) The sample bottle is filled with a solution and weighed� D) The sample bottle still filled with the solution is weighed submerged in the container of

water� The Specific Gravity is calculated as: SG = (C-A) / [ (C-A)-(D-B) ]


15.33

Measurement and Data - temperature of 62-68oF

Measured Data and Calculated Specific Gravity (SG) (at 62-68oF) [Measurement Accuracy of 0.01 gram]

Sample Weight ofEm pty b ottle

in AIR(grams)

(A)

Weight ofbottle filled w ithwater submerged

in WATER(grams)

(B)

Weight ofbottle filled withsolution in AIR

(grams)

(C)

Weight ofbottle filled

with solutionsub merged in

WATER(grams)

(D)

SG

(C-A ) / [ (C-A )-(D-B ) ][ e rro r o f + - 0 .4 % ]

Tem perature(oF)

bottle 77.73 44.22 - - - 68

A - - 157.43 54.55 1.149 65

B - - 157.71 54.95 1.155 68

C - - 158.29 55.42 1.161 62

D - 158.48 55.61 1.164 62

E - - 158.64 55.82 1.167 62

F - - 158.68 55.88 1.168 66

G - - 158.96 56.11 1.171 64

H - - 159.45 56.59 1.178 64

I - - 159.96 56.90 1.182 64

J - - 160.63 57.56 1.192 64

Note: The accumulated weights of added solids may not be apparent in (C) as some volume mayhave been displaced. The sample bottle was always completely filled and capped so as toprevent any air bubbles. However no attempt was made to measure changes in absolutevolume measured or volume displaced.


15.34

Conversion of Specific Gravity into a Solution Concentration Percentage for Ferric Oxalate using the Dick Stevens' Relationship

Sample Estimated % concentration

Measured Specific Gravity

[ error of +- 0.4% ]

Calculated % concentration

[ error of +- 3% ]

A 24% 1.149 23.5%

B 25% 1.155 24.5%

C 25% 1.161 25.4%

D 25% 1.164 25.9%

E 25% 1.167 26.4%

F 25% 1.168 26.5%

G 26% 1.171 27.0%

H 27% 1.178 28.1%

I 28% 1.182 28.7%

J 29% 1.192 30.3%

AnalysisAlthough within the error, the Stevens' Calculation of percent concentration seems to not agree withthe measurements. Before the addition of any Oxalic Acid or EDTA, the values are about 0.5%lower than the estimated, and for measurements after all additions of Oxalic Acid and EDTA, thevalues are about 1% greater than the estimated. This may be remedied in one of two ways.

� The Ferric Oxalate made by Vizcay is less pure that estimated.� The Ferric Oxalate used by Stevens contained some Oxalic Acid (or other material) which

caused his values for concentration to be too high. This could have been caused by a 1%solution concentration of Oxalic Acid in his FO solution.


15.35

Comparing Prints from Ferric Oxalate Powderscreated October 1999

Initially done as a test of the Viscay FO manufacturing process, this study complements the studyof the Initial Comparisons of Ferric Oxalate Powders. Further comparison is made in the study ofthe Relative Comparison of FO powders.

The author has used the Ferric Oxalate (FO) powder manufactured by Bostic and Sullivan (B&S)since about 1987. This has been an excellent product in both consistency and quality which wasregarded as a standard for this test by which to compare other ferric oxalate.

Working solutions identified during the comparison of several FO powders were made.

First, the FO Test described in the guide was run. The FO solutions behaved as it should and passedtest. This test basically just indicates if it is working in general, or perhaps contaminated, or not ofhigh purity.

Second, tests for clearing and fogging were performed. Clearing was complete, with clearing agentand times typically used for the paper selected. There was no noticeable fogging.

Third, identical prints using FO powder made by Vizcay (Vizcay FO), this author using Vizcay'sprocess (JDM FO) and Bostic & Sullivan (B&S FO) were compared (keeping all other things asequal as possible). Prints were made using Crane's Parchment Business Card Stock (AKA: Cover90) paper. All prints received identical coating technique (by brush), identical exposure, andidentical processing using the same negative and a 21-step.

Preliminary Prints and ResultsFour sensitizer solutions (the Oxalic Solutions and Straight Solutions from the Comparison of FOpowders) were used to make prints.

The solutions were:

Prints from Oxalic Solutions:A) 16.20 grams B&S FO powder, plus 52.5 ml H2O, plus 0.50 g Oxalic AcidB) 16.20 grams Vizcay FO powder, plus 52.5 ml H2O, plus 1.40 g Oxalic Acid

Prints from Straight Solutions:C) 25.9 % solutions B&S FO powder only (no additional Oxalic Acid)D) 25.9 % solutions Vizcay FO powder only (no additional Oxalic Acid)


15.36

Preliminary observations indicated:

� Both A & C (B&S powder) are slightly warmer in color than B & D (Vizcay powder).� A & C are the same color� B & D are the same color� A & B (Oxalic Solutions) show more sharpness and better tonal discrimination than their

counterparts, C & D (Straight Solutions). It can not yet be determined if the observed effectsare due to the Oxalic Acid or the higher solution concentrations. Further study is planned.(See the study Oxalic Acid Concentration in the FO Sensitizer.)

� A & B (Oxalic Solutions) seem prone to solarization effect in values below zone I.� A & B (Oxalic Solutions) have the same speed and contrast.� C & D (Straight Solutions) have the same speed and contrast.� C & D (Straight Solutions) are almost 1/2 stop faster than their counterparts A & B (Oxalic

Solutions) and have the same contrast.

Aside from the color mentioned, no substantial difference was detected in the prints betweenVizcay's FO powder and the standard B&S FO powder. Difference were noted in that the printsfrom the Oxalic Solutions were about 1/2 stop slower, had better sharpness, and had better tonaldiscrimination than prints from the Straight Solutions.

Prints and Results from Balanced SolutionsIn order to make an accurate comparison, sensitizer solutions were made having the sameconcentration of ingredients as best as could be determined from the Comparison of FO Powdersstudy. The Ferric Oxalate was mixed to a solution strength of 30%. The metal solutions were mixedas optimized to be used with the 30% FO.

Prints were made using the following solutions of Ferric Oxalate sensitizer.

Prints from Balanced Solutions:E) 8.45 grams B&S FO powder (assumed to contain 0.91 g Oxalic Acid & 7.54 g FO)

1.00 gram EDTA (Na4)0.04 gram Oxalic AcidH2O to make final volume of 25.12 ml(concentrations: 30% FO, 3.8% Oxalic Acid, 4% EDTA)

F) 7.65 grams Vizcay FO powder (assumed to contain 0.15 g Oxalic Acid & 7.50 g FO)1.00 gram EDTA (Na4)0.80 gram Oxalic AcidH2O to make final volume of 25.0 ml(concentrations: 30% FO, 3.8% Oxalic Acid, 4% EDTA)

G) 7.65 grams JDM FO powder ( assumed to contain 0.15 g Oxalic Acid & 7.50 g FO)1.00 gram EDTA (Na4)


15.37

0.80 gram Oxalic AcidH2O to make final volume of 25.0 ml(concentrations: 30% FO, 3.8% Oxalic Acid, 4% EDTA)

Observations of Prints from Balanced Sensitizer Solutions:

� E, F, & G have the same speed and contrast.� The speed and contrast of E, F, & G (Balanced Solutions) is the same as A & B (Oxalic

Solutions).� E & F have the same color, G may be barely slightly warmer but very close to E & F.� The color of E, F, & G (Balanced Solutions) appears slightly more neutral than the color of

B & D.� The very high tonal values (Zones above IX) in print G seem to be cleaner and have better

definition.� The dark values of E, F, & G (Balanced Solutions) are the same and are darker/blacker than

A, B, C, & D. Prints from the Balanced Solutions did not show any signs of solarizationeffect, however the dark values of Zones I and II (where there was no indication ofsolarization effect in the prints from Oxalic Solutions) were darker/blacker as well.

� E, F, & G (Balanced Solutions) look identical in all other aspects.� E, F, & G (Balanced Solutions) have more sharpness than C & D (Straight Solutions), but

not quite as much as A & B (Oxalic Solutions).� E, F, & G (Balanced Solutions) and A & B (Oxalic Solutions) have excellent and close to

identical tonal discrimination.

Additional prints using sensitizer E, F, & G were made on Bienfang 360 and repeated on the Cranepaper with a different negative and the 21-step. Results were identical to and confirmed thoseabove.

No substantial difference is observed between the Balanced prints E, F, & G, except for the slightlybetter upper highlight definition found in print G. The improved upper highlight definition may berelated to preparation conditions of the FO powder; further study is warranted.

ConclusionsVizcay's preparation procedure allows one to make an unsurpassed, high quality Ferric Oxalatepowder suitable for use as a sensitizer with the Pt/Pd process helping produce prints of the highestquality.

The balanced solutions produce identical prints.


15.38

Further Study

Studies are planned to investigate the effects of the amount of Oxalic Acid and pH of the FOsensitizer solution; the threshold of total concentration of the coating mixture, and preparationconditions (including residual HNO3 content) which may affect highlight values. Other studies ofmerit could include investigations of other sensitizer solutions and other preparation methods. Themeasurement of specific gravity should be improved so as to make an accurate method of mixingknown Ferric Oxalate concentrations.


15.39

Relative Comparison of FO Powders Using Printscreated December 1999

In order to achieve accuracy and consistency in Pt/Pd prints, it is important to begin with anaccurately formulated sensitizer to which the metal solution will be balanced. Determining theabsolute active Ferric Oxalate content of a selected powder may be of a higher than desireddifficulty level and require sophisticated laboratory equipment. The author considers chemistryoperations such as titration to be of a more advanced level than typically practiced by the Pt/Pdprinter. A relative comparison was devised and presented below to compare different FO powdersand determine a solution concentration for them which would meet or exceed the threshold neededto produce maximum quality prints. The threshold is that point at which no additional metal in thefinal print can be seen to make a difference.

The Comparison of FO Powders Study indicated that FO Powders are not all the same. That studyattempted to estimate the contents of some FO powders. The Verification of FO Powders Studyattempted to estimated FO content using the specific gravity of solutions. It was found that thesestudies could only estimate the composition of the FO powders.

Since those studies, Vicente-M Viscay has sent me three samples of powder and crystalline FO, onebeing an ultra-fine Ferric oxalate powder. This study investigates the threshold relative to printsusing several FO powders and then compares the FO solutions. The study is outlined as follows:

Procedure:� First, identical solutions are made at a high concentration assuming that all powders are

100% pure FO. High concentration means one that should be above the threshold. In thisstudy, 30% is used.

� A coating mixture is made by adding the appropriate metal solution for a 30% FO sensitizerfor each FO powder type..

� Prints are made using these coating mixtures.� Prints are made from incrementally diluted coating mixtures so as to determine a threshold

level for each FO powder type.� The ferric oxalate content of the ultra-fine FO powder is assumed to be as assayed by

Viscay.� All other FO powders had there ferric oxalate content calculated by normalizing them to

have the same threshold relative to the ultra-fine FO powder samples.

The accuracies involved with this study were kept pertinent to the accuracy of Pt/Pd printmaking.Weights measured to 0.01 grams.Volumes measured to 0.05 ml (drop size as determined from 200 drops per 10.0 ml)Sensitizer solutions varied at 1% increments (3% to 4% total volume).Print evaluations of threshold made by both reflected and transmitted light by eye usingstrong light.


15.40

Sensitizer Solution Components

Material Description Analysis

FO-UF ultra-fine FO powderProduct obtained: Ferric oxalate 6-hydrateProducer: Vicente-M. VizcayProduct number: Exp (15)Quality: Pure; ACSGuarantee: 98,0 - 99.5 % of purity

Guarantee Specifications(general, anions and cations)Ions Limits (always less than .. %)Free oxalic acid: 0.46%Free nitric acid: 0.77%Free water: 0.66%Chloride (Cl1-): 0,0005%Phosphate ((PO4)3-): -%Sulphate ((SO4)2-): 0,0050%As: -%Ca: 0,0020%Cd: 0,0010%Co: 0,0010%Cr: 0,0050%Cu: 0,0010%Fe2+: 0,0020%K: 0,0050%Mg: 0,0010%Mn: 0,0050%Na: -%N: -%Ni: 0,0010%Pb: 0,0010%Zn: 0,0010%

FO-V Ferric oxalate hexahydrateFe2(C2O4)3.6H2O(CAS number: 19469-07-9)Producer: Vicente-M. VizcayThis is the FO powder used in other studies

?

FO-J Ferric Oxalate powderProducer: Jeffrey D. MathiasMade from Vizcay FO preparation procedure

?

FO-BS Ferric Oxalate powderProducer: Bostic & Sullivan

?

FO-AC Ferric Oxalate powderProducer: Artcraft

?


15.41

EDTA ethylene diamine tetra-acetic acid (EDTA). Synonyms: EDTA; Complexone IIMolecular Formula: C10H16N2O8Molecular Weight: 292.25CAS: 60-00-4Purity Grade: pure

H2O Distilled water

Paper: Crane's Parchment Business Card Stock (AKA: cover-90; "platinotype")

Coating Mixture:6 drops sensitizer solution (one of those above)4 drops K2PdCl4 metal solution2 drops K2PtCl4 metal solution

Coated area: 127mm x 127mm (5" x 5")Coated by brush

Exposure: x minutes with UV -BL lamps

Processing:1 minute in standard potassium oxalate bath2 minutes in water bath30 minutes in three clearing baths (2oz 85% H3PO4 per gallon water)1 minute rinse in water with baking soda10 minute wash in water

Nine prints were made for each of the five FO powders in solution concentrations from 30% to22%% in 1% decrements assuming each powder was 100% pure. The threshold was determined byobservation of the prints produced by each solution of each of the FO powders.Results:FO powder solution percentage of sensitizer

at which threshold is passedby observation of prints

calculatedpercentage of active sensitizer

in powder based on observed threshold

FO-UF 25 98

FO-V 26 94

FO-J 26 94

FO-BS 27 91

FO-AC 26 94


16.1

Chapter 16 - More StudiesStudy of Oxalic Acid Concentration in the FO Sensitizercreated October 1999

The purpose of this study was to determine what (if any) effects are related to the amount of OxalicAcid in the Ferric Oxalate (FO) sensitizer solution.

A low Oxalic Acid solution was needed for the base of this study. The Vizcay "EDTA Solution"from the Comparison of FO Powders study was modified so as to provide a 30% FO solution.

8.00 grams Vizcay FO Powder (estimated to contain 0.15 g Oxalic Acid & 7.85 g FO)1.05 gram EDTA (CAS: 60-00-4)H2O to make 26.2 ml when completely dissolved

The composition of this Base Solution contains concentrations of

30% ferric oxalate4% EDTA (CAS: 60-00-4)0.587% oxalic acid

The metal solution formulas used with this 30% FO sensitizer can be determined using the FormulaCalculator or Quick Formula Table in Chapter 6, Optimized Formulas for Metal Solutions. Acoating mixture was mixed consisting of:

7 drops sensitizer (described above) (30 % solution)5 drops K2PdCl4 solution (20.2 % solution, warmed)2 drops K2PtCl4 solution (25.7 % solution, warmed)

The remaining Base Solution had oxalic acid added, another coating was produced, and this wasrepeated until the following coating mixtures were made containing the following concentrationsof Oxalic Acid. The pH of the sensitizer solution was measured, but not of the coating mixture.There were concerns that pH measurement of the relatively small amounts of coating mixture mightalter the amount of the coating mixture as the probe can carry off several drops.


16.2

% concentration OxalicAcid

in sensitizer solution

pH (± 0.1)

0.587 0.6

1 0.3

2 0.1

3 0.0

4 0.0

5 0.0

6 0.0

8 0.0

10 0.0

� Ambient conditions were temperature of 66oF, relative humidity of 34-36%.� The paper used was Crane's Parchment Business Card Stock (AKA: Cover-90; CP)� Coatings were by brush into an area 5 inches by 5 inches (25 inches2 or 161 cm2)� All were dried by the dry method (see Drying the Coating).� All were exposed with the same negative and a 21-step for 10.5 minutes under UV lamps.� All were processed the same:

� developed in Potassium Oxalate� 2 minutes water bath� 30 minutes total clearing in H3PO4 (3 baths).� Buffered rinse and 10 minute wash.

ObservationsAt first look all the prints seemed identical. Closer observation revealed that:

� As Oxalic Acid concentration increased the speed may decrease by about 0.125 stop from0.587 to 10. This is not a large change, but noticeable on the 21-step.

� Prints with Oxalic Acid concentrations above 2% seem to have better tonal discriminationand separation (perhaps from an edge effect) and better sharpness.

� Prints with Oxalic Acid concentrations above 5% seem to be fuzzier (perhaps from someincreased graininess, increasing with 10 having the most). The fuzziness offsets (6%) andthen more than offsets (8% & 10%) any gain in sharpness.


16.3

ConclusionsOxalic Acid concentration from 2% to 5% in the sensitizer solution may be beneficial providingbetter sharpness and better tonal discrimination with higher concentrations progressively causinggraininess. The resulting effects are very slight.


16.4

ConsiderationsMaterialsProcessingNomenclatureObservationsConclusionsRecommendations

Study of the Clearing of Pt/Pd Printscreated April 2000, updated (format & editorial only) Dec. 2000, note added Aug. 2001

This study has documented some very significant findings concerning theclearing of Pt/Pd prints. This study makes use of the revised clearing testinvolving the use of Potassium Ferricyanide as an indicator. Thanks toJohn Melanson for suggesting the use of this indicator.

Several past observations have been made and verified and can beconsidered general trends concerning clearing.

� Most thin papers clear better and/or faster than thicker papers.

� POP type prints using Ammonium Ferric Oxalate sensitizer may clear in about half the timeof DOP type prints using Ferric Oxalate sensitizer. This from previous work and notinvestigated further in this study.

� Prints made with a lower solution concentration of the coating ingredients will clear slightlyfaster. However, it must be remembered that a certain threshold concentration must be usedto avoid weak prints. This from the Threshold Study.

The most significant finding with this study is that an addition of Oxalic Acid and EDTA to thesensitizer solution dramatically reduces clearing times. (See the procedure and results below fordetails.)

Only single agents were used for this study. It is suspected that a series of multiple agents mightprovide improved clearing, however the possibilities of combinations are numerous and may becomea mute point at the conclusion of this study.

CRITICAL CONSIDERATIONS:It is most important that the following be considered carefully as they can have a dramatic influenceon clearing investigation. All relate to fogging, which may appear to be incomplete clearing.

� A safe light MUST be used. Work lights must be tested to assure that they will not fog thecoating. Sodium vapor lights are an excellent choice.

� Coating brushes should be kept clean. Old sensitizer material can get into the print causinga fogging effect. Brushes should be rinsed well in distilled water and squeegeed dry witha paper towel after each use. Brushes should then be stored in a light tight box or bag.

� Fresh developer should be used. Developer that has been used for many prints may containexposed material that may react with or lodge onto coatings causing a fogged appearance.


16.5

This was a culprit in this study resulting in a lack of clearing in a reasonable time. Whennew developer was used, the repeated tests showed dramatically improved clearing. Itshould be routine practice to replace the developer rather than continuously replenish.

� Cross contamination can be a problem. The initial clearing indicator of a 10% solution ofPotassium Ferricyanide proved to be too sensitive. Uncoated samples were processed alongwith the other samples and although nothing could be detected without the indicator, theindicator would show some blue. Cross contamination is suspected to occur from useddeveloper, rinse, clearing baths, and especially wash water. When samples were processedindividually with fresh solutions and wash water, the false indications did not occur.However, it was not practical to process hundreds of samples with individual fresh baths andwashes. Thus, a 1% solution of Potassium Ferricyanide was prepared and applied bysmearing a little on with a clean, fresh Q-tip.

Notes: If a Q-tip with indicator solution touches an uncleared sample, it can produce falseblue indications on a cleared sample. Also it is recommended to use a dropper todrop indicator solution onto the Q-tip, without touching. Do not dip the Q-tip intothe solution. Also any trace of metal in the Potassium Ferricyanide solution maygive a false blue color.

� Evaluation was made relative to any indication on uncoated samples. This crosscontamination is not critical for individual prints, but should be a consideration forproducing archival prints. The final clearing bath and wash water should always be fresh.Also it must be remembered that the clearing indicator can be so sensitive as to give falseindications and should be checked and referenced with a uncoated control.

MATERIALS:For simplicity, only one paper was used, Crane�s paper (lot# 5302). This is a thick and traditionallylong to clear paper (typically 40 to 60 minutes, sometimes longer). Other papers may have differentclearing times and/or respond to various clearing agents differently.

Several clearing agents were tested. Water was 0.5 um filtered tap water.

Code(used for this study)

Agent Description

P Phosphoric Acid (H3PO4) 2 ounces of 85% reagent gradeper 1 gallon water

C Citric Acid 20 grams per 1000 ml water(2% solution)


16.6

S Sodium Bisulfate 20 grams per 1000 ml water(2% solution)

F Sprint Fixer Remover label directions(1 part plus 9 parts water)

E EDTA (Na4) 40 grams per 1000 ml water(4% solution)

W water 0.5 um filtered tap water

Notes: HCl (Hydrochloric Acid) was not included because previous use has demonstrated that itcan bleach the highlights of the print. However, the HCl may work fine (without bleaching)at the shorter clearing times this study demonstrates and should not be dismissed withoutfurther testing.

Potassium Meta Bisulfite worked well but gave off too much sulphurous fumes so waseliminated from most of the tests and is not reported.

Several Ferric Oxalate powders were investigated. However, results were a factor of theadditives rather than the powder used. The Vizcay powder was selected as its compositionand purity is best known. The addition of Oxalic Acid and EDTA to the sensitizer made asignificant difference in clearing ability. 3% Oxalic Acid was included because previousstudy indicated an advantage of having from 2% to 5% and 3% is typically used. 3% EDTAwas initially selected being the same concentration as the Oxalic Acid. When used together,1% EDTA was found to be more than adequate.

The EDTA was subsequently reduced to a range of 0.04% to 0.1% from the 1% used in theClearing Study. The reason was that some "bleeding" of the metals may occur in the printnoticeable as washing off or flowing through the substrate. The "bleeding" did not occurat the lower amount.

Sensitizer and Additives Tested

SensitizerCode

Description

V Vizcay Ferric Oxalate at 24% (Vizcay�s preparation procedure)

VO Vizcay Ferric Oxalate at 24% plus Oxalic Acid at 3%

VE Vizcay Ferric Oxalate at 24% plus EDTA at 3%

VOE Vizcay Ferric Oxalate at 24% plus 3% Oxalic Acid plus 1% EDTAfor example:VOE = 24.00 g FO + 3.00 g Oxalic Acid + 1.00 g EDTA + H2O to make 100 ml


16.7

EDTA used as a sensitizer additive was ethylene diamine tetra-acetic acidSynonyms: EDTA; Complexone IIMolecular Formula: C10H16N2O8Molecular Weight: 292.25CAS: 60-00-4Purity Grade: pureNote: This is NOT the same EDTA(Na4) used as a clearing bath. The EDTA(Na4)

tested as a clearing bath was some sent to me by John Melanson.

The metal salt solutions were K2PdCl4 (16.2%) and K2PtCl4 (20.6%) in a ratio of 5 parts Pd and 2parts Pt. The strengths of these solutions is that calculated to work with the 24% FO sensitizerstrength.

PROCESSING:All samples were processed as follows:

� coating mixture mixed (as for a 4x5 print)� brush coated (with coating edges indicated and as instructed in Test for Clearing)� dried� identified with marks and then cut into samples� 1 minute in Potassium Oxalate (developer and all baths at ambient temperature)� 2 minutes in water� # minutes in clearing agent� 5 minute wash in water� dried� evaluated� exposed for 12 minutes with UV lamps (about double typical printing time)� Potassium Ferricyanide (1% solution) applied (smeared on with clean Q-tip) to part of coated

area� 2 minutes rest� 10 minute wash to remove all yellow from Potassium Ferricyanide� dried� evaluated

Note: If one uses a different developer or different conditions, those should be used for the test.

IDENTIFICATION & NOMENCLATURE:Samples are referred to as X# whereX = the code letter of the clearing agent# = number of minutes in the clearing agent


16.8

Observations of the evaluations are coded as follows:CODE color Description

For areas without Potassium Ferricyanide: (colors shown are approximate)

x no sample

0 identical to uncoated paper

1 very faint gray color (the slightest distinction)

2 light gray color

3 gray color

4 light brown or light yellow-brown color (may include gray)

5 brown or deep yellow-brown color (similar to coating color)

For areas with Potassium Ferricyanide: (colors shown are approximate)

nocode

no change

a faint blue color

b blue color

Note: Consideration should be given for unnecessary cross contamination and any slightly �0a� rated samples might be considered completely clear.

For example:3b - means the coated area was a gray color and the area with Potassium Ferricyanide was

a blue color.1 - means the coated area was only a very faint gray color and the area with Potassium

Ferricyanide showed no change (remained a very faint gray color).


16.9

OBSERVATIONS:The following clearing results as a function of agent and time are shown for several sensitizers. Thelast data set compares use of an old developer.

Time (minutes) > 5 10 15 20 30 40

For V sensitizer (FO only):

P 5b 4b x 3b 2b 1a

C 5b 4b x 3b 1b 1b

S 5b 4b x 3b 2b 1a

F 2b 1b x 1a 0a 0a

E 4b 3a x 2a 2 2

W 5b 5b x 4b 4b 4b

For VO sensitizer (FO + OA):

P 2b 1b x 1b 1b 1a

C 1b 1b x 1a 1a 0a

S 2b 2b x 1b 1b 1a

F 1b 1b x 0 0 0

E 1a 1a x 1a 0 0

W 3b 1b x 1b 0b 0b

For VE sensitizer (FO + EDTA):

P 1a 1a 1 0 0 x

C 1a 1 1 0 0 x

S x x x 1a 0 x

F 1a 1a 0 0 0 x

E 1a 0a 0 0 0 x

W x 1b x x 1a x


16.10

Time (minutes) > 5 10 15 20 30 40

For VOE sensitizer (FO + OA + EDTA):

P 0a 0a 0a 0a x x

C 0a 0a 0a 0a x x

S 0a 0a 0a 0 x x

F 0a 0a 0 0 x x

E 0a 0a 0 0 x x

W 1b 1b 0b 0a x x

For comparison, with old developer VOE gave the following results:

P 2b 2a 2a 2a 1a x

C 2b 2b 2a 1a 1a x

S 2b 2b 1a 1a 1a x

F 2 2 1 1 1 x

E 2 2 2 2 1 x

W 2a 2a 2a 2 2 x

CONCLUSIONS:

� The addition of either Oxalic Acid or EDTA to the Ferric Oxalate (FO) sensitizer solutionimproved clearing and reduced clearing times.

� Best clearing results were obtained when both Oxalic Acid and EDTA were added. Notethat even water (without any clearing agent) cleared completely in 20 minutes plus washwhen both Oxalic Acid and EDTA were added.

� A used developer can dramatically hinder clearing.

� The choice of sensitizer additive and a fresh developer is more important to good clearingthan the choice of clearing agent.


16.11

RECOMMENDATIONS:

� For proper clearing of Pt/Pd prints it is recommended that Oxalic Acid (3%) and EDTA(0.04%) be added to the Ferric Oxalate sensitizer solution.

Notes: Previous work from the Threshold Study has shown the addition of up to 5% ofOxalic Acid to the sensitizer does not seem to degrade the quality of the print.

Work subsequent to this study reduced the EDTA from 1% to 0.4% then added8/2001: Further study of the "bleeding" of metal during processing has indicated thattoo much EDTA seems the culprit. It is now recommended that EDTA in thesensitizer be kept to a solution strength of between 0.04% and 0.1%. The actualamount can vary with different papers, so the smallest amount of EDTA to add to thesensitizer to assist with clearing should be determined for each paper.

� Since Potassium Meta Bisulfite produces a strong sulphurous odor (especially when used inan open tray), it is NOT recommended as a clearing agent.

� Sprint Fixer Remover is a good choice for the selected paper as it provided the best andfastest clearing in every case. A different paper may favor another clearing agent.

� A total wash time of 10 minutes with at least one change of fresh water is recommended.

� Recommended times for clearing the selected paper (CP) are:� 10-15 minutes for the Sprint Fixer Remover or EDTA(Na4) giving a total processing

(develop through wash) time of 23-28 minutes.� 15-20 minutes for Sodium Bisulfate giving a total processing (develop through wash)

time of 28-33 minutes.� 20 minutes for Phosphoric Acid or Citric Acid giving a total processing (develop

through wash) time of 33 minutes.

� It should be routine practice to replace the developer after a large amount of coatings whilereplenishing for developer carried off by prints.

Have a clear day.


16.12

A Look at Grain in the Film and Details in the Printcreated December 2000 (original data May 1986)

A negative with more pronounced grain can allow for better detail in the Pt/Pd print. It seems thatedges of tones in a Pt/Pd print are better discriminated when there is adequate grain in the negative.

The same scene is recorded on films having different grain. Of the films selected, Tri-X has a goodamount of grain and Tech-Pan has almost no grain. Pt/Pd prints are made from each negative andcompared. The negatives have been reversed for ease of comparison. Please be aware that someof the details of interest are on the order or smaller than the resolution of the scan (1200 ppi); theoriginals viewed with a magnifier demonstrate this effect better than these scans.

The selected portion of the full 4x5 negative is as approximately indicated here:


16.13

A Look at Grain in the Film and Details in the Print

Portion of Tri-x negative. Portion of Tech-Pan negative.

Notes: Note better details in the Tech-Pan negative.What looks like grain in the negatives (above) is only artifacts of the scan.What looks like grain in the prints (below) is the texture of the paper surface.

Pt/Pd print from Tri-X negative.This print has better detail than the print from theTech-Pan negative. The power lines areespecially better discerned when viewed with amagnifier.

Pt/Pd print from Tech-Pan negative.The power lines merge in places even whenviewed with a magnifier. Also note less of anedge definition of the stacks, and less bridgedetail.

Note: No sharpening was used in any of the images. The negatives and prints were scanned at 1200ppi. Many differences are outside of the scan resolution, but can be observed with a magnifier.

Documents

Platinum-Palladium Photographic Printmakingjeffreydmathias.com/guide/PtPdPhotographicPrintmaking.pdf · ~~~~~ Guide to Platinum-Palladium Photographic Printmaking by Jeffrey D. Mathias