This page contains list of various types of pulp and paper based on their end use, process of manufacturing, raw material used etc. Papers can be graded in 'n' numbers of ways and if we count all permutation and combination of grades total grades may well exceed 10000. Some of the major grades classifications are;1. Based on basis weight

Tissue: Low weight, <40 g/m2 Paper: Medium weight, 40 - 120 g/m2 Paperboard: Medium High weight, 120-200 g/m2 Board: High weight, >200 g/m2

2. Based on Color Brown: Unbleached White: Bleached Colored: Bleached and dyed or pigmented

3. Based on UsageIndustrial: Packaging, wrapping, filtering, electrical etc. Cultural: Writing, printing, Newspaper, currency etc. Food: Food wrapping, candy wrapping Coffee filter, tea bag etc.

4. Based on Raw Material Wood: Contain fibers from wood Agricultural residue: Fibers from straw, grass or other annual plants Recycled: Recycle or secondary Fiber

5. Based on Surface Treatment Coated: Coated with clay or other mineral. Uncoated: No coating Laminated: aluminum, poly etc

6. Finish Fine/Course calendered/ supercalendered Machine Finished (MF)/Machine Glazed (MG) Glazed/Glossed

A

Abrasive Papers Papers covered on one or both sides with abrasive powder, e.g. emery, sandpaper etc.

Absorbent Paper Papers having the specific characteristic of absorbing liquids such as water and ink. These papers are soft, loosely felted, unsized and bulky e.g. blotting paper.

Acid Free Paper A type of paper, which does not contain any acidic substance that may affect acid sensitive material. Acid free paper is anti rust and is used for metal wrapping.

Acid Proof Paper A paper that is not affected by acid physically or chemically. This paper is used with substance containing acid.

Account Book Paper Paper  primarily used for pen and ink writing. It is usually made from cotton fibers or bleached chemical pulp or a mix of two. It has good strength, erasability and resistance to water and ink.

Adhesive Paper Base paper for coating with an adhesive, the type depending upon end use.

Air Dried Paper Paper dried by direct contact of heated or ambient air.

Air Filter Paper A type of paper used for filtration of air to remove suspended particles. (car air filter, vacuum bag etc.)

Air Mail Paper It is lightweight, high opacity, good quality writing/printing type paper used for letters, flyers and other printed matter to be transported by airlines.

Album Paper Paper used in photographic albums.It has a soft surface which will not wrinkle or cockle when photographs are pasted or glued on it, and when wet with such adhesive, it will not 'bleed'.

Albumin Paper A coated paper used in photography; the coating is made of albumen (egg whites) and ammonium chloride.

Alkaline Paper Paper having pH values greater than 7 and made by using an alkaline sizing process.

Alkali Proof Paper A paper, either white or colored, which does not discolor when in contact with alkaline materials, such as soap. Careful selection of fibers and coloring matters is necessary, but no particular strength$ requirements need be met. Many book papers are sufficiently alkali-proof and glassine and waxed papers are also satisfactory.

Alligator Imitation Paper A cover paper embossed to resemble alligator leather. It is used for book cover, wallet and large envelopes.

Aluminum Paper A wrapping paper made by mixing aluminum powder in to pulp furnish or by coating the sheet with aluminum powder. It is used in food and tobacco wrapping. When used in general label work, it is referred as silver label paper.

Aluminum Foil Lamination The combination of thin Aluminum foil with a paper backing used as a positive moisture barrier. Normal combination is kraft backing with Aluminum foil laminated to the kraft by means of asphalt, adhesive, or polyethylene. The Aluminum foil can also be coated with polyethylene.

Ammunition Paper The type of papers used in the manufacture of ammunition such as cartridge paper, which forms the tube section of shotgun shell and basewad paper, which is used in the base of the shell.

Analytical Filter Paper   A type of low ash content paper with high filtering rate that does not allow particles or precipitates pass when slutty are poured over it. It is used in chemical labs foe analytical testing. 

Announcement Cards Paper  Cards of paper with matching envelopes generally used for social stationery, announcements, weddings, greetings, etc.

Anti Rust Paper

Paper containing added substances which give it the property of protecting the surfaces of ferrous metals against rusting.

Anti-Tarnish Paper A term originally applied to tissues used for wrapping silverware, but now used for all papers so prepared that they will not rust or discolor razor blades, needles, silverware, etc. Various fibers are used and weights of paper made; the chief requirements are freedom from acidity and reducible sulfur compounds. Copper salts or other inhibitors are sometimes used for silver tissues.

Antique Paper Printing paper having good bulk and opacity with rough or matt surface.

Archival Paper A paper that is made to last for long time and used for long lasting records.

Art Paper High quality and rather heavy two-side coated printing paper with smooth surface. The reproduction of fine screen single- and multicolor pictures ("art on paper") requires a paper that has an even, well closed surface and a uniform ink absorption.

Artificial Parchment Wood free paper that is produced by fine and extended grinding of certain chemical pulps and/or the admixture of special additives. As a result of the "smeary" grinding, the fiber structure closes homogeneously. It is used e.g. for wrapping meat and sausages or as corrugating medium for biscuit packaging

Asbestos Paper A fire retardant and heat insulating paper made chiefly from asbestos fiber on a cylinder machine. Generally not over 0.06 of an inch thick.

Asphalt Laminated Paper Two sheets of natural kraft paper laminated in a single ply by means of asphalt. This is used as a moisture barrier; also to resist action of weak acids and alkalis .

Azurelaid Paper A laid paper usually bluish green in colour having a good writing surface.

B

Back Liner The back side layer in a multi-ply paperboard. Normally back liner is made out of inferior grade pulp compared to top liner.

Bacon Paper A single ply or laminated with grease resistant wrapping, usually made from glassine paper, used to wrap bacon or other fatty meat. Also known as Bacon Wrapper.

Bag Paper Any paper made to be used in the manufacturing of bags.

Bagasse Paper Paper made from bagasse pulp.

Bakelite Paper or Hard Paper

A hard sheet made by saturating soft paper with resin, which is then polymerized to a Bakelite like material by drying, curing and pressing under high pressure and temperature.

Bakers' Wrap A paper used by bakers for wrapping bakery goods. It has high brightness, good finish and strength.

Balloon Paper A paper used for toy hot air balloon. It is well sized, nonporous and pinhole free.

Banknote or Currency Paper Used for printing currency. De-facto highest grade of paper. Very high folding endurance, permanency, tensile strength, suitable for 4-colour printing, with watermark and other falsification safeguards such as embedded metal strip. Often contains cotton fibers.

Barograph Paper Red thin paper coated on one side with a white wax, so that the needle of the barograph leaves a red line on a white ground, sold in rolls and coils and to suit the type of barograph.

Barrier  Paper Specially treated, coated and/or laminated paper to provide resistance to passage of vapor, gas, moisture, oil, water or other fluids.

Baryta Paper A paper coated with barium sulfate to give a smooth, low-gloss surface; used chiefly as a base for photographic emulsions.

Base Paper Refers to paper that will be subsequently be treated, coated or laminated in other ways.

Beedi Wrap Paper Used for wrapping beedi (east Indian style cigarette) and decorative purposes in different colours.

Beer Filter Paper Filter paper specially made from long fiber pulp, used in the centrifugal clarification of beers.

Bible Paper Thin white opaque heavily loaded, used for printing bibles. Not suitable for pen and ink, because of its absorbency.

Black Waterproof Paper An asphalt impregnated paper usually made from jute fibers, used as insulation for roofs, walls, and floor in building construction.

Blade Wrapping Paper Translucent paper used for individual wrapping of razor blades.

Blanks A name applied to thick cardboards, coated or uncoated, pasted or unpasted, and made in standard thicknesses with either white or colored liners. They should have maximum smoothness of surface and stiffness. They range from 0.012 to 0.078 of an inch with corresponding ream weights of 120 to 775 pounds (22 x 28-500). Their use is for calendar backs, signs, and window displays.

Bloodproof Paper or Butcher Paper A high strength paper having maximum resistance to animal blood. It is used for wrapping fresh meat. It is normally sized with wax emulsion or other anti-absorption chemicals.

Blotting Paper An un-sized paper used generally to absorb excess ink from freshly written manuscripts, letters and signatures.

Blueprint Paper Base paper for blue printing. See Diazo Base Paper.

Board Thick and stiff paper, often consisting of several plies, widely used for packaging or box making purposes. Its grammage normally is higher than 150 g/m2 or thickness is more than 9 point (thousandth of an inch).

Bogus Paper Bogus refer to a product that is made from recycled fiber or an inferior pulp to imitate higher quality grades. There are bogus back liner, bogus bristol, bogus kraft, bogus wrapping etc. Gray bogus is used for packaging material, void fill, wipes, bedding, and a variety of other industrial and agricultural purposes. It is biodegradable.

Bond Paper The name "bond" was originally given to a paper, which was used for printing bonds and stock certificates. It is now used in referring to paper used for letterheads and many printing purposes. Important characteristics are finish, strength, freedom from fuzz, and rigidity.

Book Paper A general term used to define a class or group of papers having in common A paperboard used in the manufacture of light non-corrugated container.

Boxboard A class of board frequently lined on one or both sides, with good folding properties and used for making box and cartons.

Braille Printing Paper Used for embossing dot patterns used by blinds in touch reading. It is bulky. The sheet must be smooth so the dots will be pronounced. The caliper should be uniform, so all dots are of same height.

Bread Wrapping Paper Used for wrapping sliced bread. It is thin, waxed paper normally made opaque for printing by loading with titanium dioxide.

Bristol Board A fine quality cardboard made by pasting several sheets together, the middle sheets usually of inferior grade.

Business Form Paper Used for business forms and data processing such as computer printouts.

Butter Wrapping Paper Paper, which is used for wrapping butter, margarine etc.

Burnt Paper Paper, which has been discolored and is brittle, but otherwise intact.

C

Cable Paper A strong paper suitable for cutting into narrow strips and winding on wire as insulation. High tensile strength is essential.

Calf Paper A book printing type of paper with a surface looking like leather.

Calico Paper Type of paper with a surface look like calico mainly used for decoration.

Candy Twisting Tissue A light-weight paper, generally waxed for wrapping candy kisses, taffy, etc.

Canvas Paper Embossed paper with a surface appearance of canvas cloth.

Carbon Paper A low basis weight paper (8 to 15 g/m2) with very low air permeability, free of pin holes and with a waxy coating, that is used to produce carbon copies on typewriters or other office equipment.

Carbonless Paper A paper that uses a chemical reaction between two different contacting coatings to transfer image when pressure is applied.

Cardboard A thin, stiff paperboard made of pressed p

Carton board A rigid wood fibre based packaging material. Carton-board is normally of at least 180 g/m2 substance and 250 microns thickness.

Cartridge paper Tough, slightly rough surfaced paper used for a variety of purposes such as envelopes; the name comes from the original use for the paper which formed the tube section of a shotgun shell.

Cast Coated Paper A coated paper with high gloss and absorptivity in which the coating has been allowed to harden or set while in contact with a mirror like polished chrome surface.

Catalogue Paper A light weight, highly opaque and good strength paper typically used for mail order catalogue and telephone directory.

Chart Paper A paper with the characteristics of bond or ledger papers. It must have good printing and erasing properties and low expansion and contraction with changing humidities. Used for making charts and graphs.

Check or Cheque Paper (MICR) A strong, durable paper made for the printing of bank checks or cheques. By careful formulations the paper is designed to react against a wide range of ink eradicators. It gives a characteristic coloured stain of "flare up" on contact with acid, alkali, bleach and organic solvents like acetone, benzene, ethanol.

Cheese Wrapping  Paper

Any type of paper used by the food industry to wrap cheese. Chipboard

A paperboard, thicker than cardboard, used for backing sheets on padded writing paper, partitions within boxes, shoeboxes, etc.

Chromo A term used to describe both papers and boards used for subsequent brush coating. The various qualities are determined both by the actual grade of base material used and the quality of the coating, which may be gummed. Coating may be applied to one or both sides, depending on end use.

Cigarette Paper This light weight, unsized paper (grammage 18 to 24g/m2), converted to improve glowing. It normally has approx. 30% calcium carbonate as filler to control the burning rate and match it with tobacco burning rate. Very long fiber such as jute, cotton etc is used to achieve high strength and porosity.

Clay Coated Boxboard A grade of paperboard that has been clay coated on one or both sides to obtain whiteness and smoothness. It is characterized by brightness, resistance to fading, and excellence of printing surface. Colored coatings may also be used and the body stock for coating may be any variety of paperboard.

Coarse Paper (also Industrial Paper) Various grades of papers used for industrial application (abrasive, filter etc.) rather than cultural purposes (writing, printing etc.)

Coated Paper Term that applies to paper which has a special coating applied to its surface. Material such as clay, casein, bentonite, talc, applied by means of roller or brush applicators; or plastics applied by means of roll or extrusion coaters.

Coated White Top Liner White liner that is coated to produce superior printability.

Cockle Finish Paper A finish that simulates characteristics of hand made paper with a wavy, rippled, puckered finish. The effect is obtained by air drying the paper under minimum tension.

Coffee Filter Paper Used for coffee filtering. Paper should have no impurities or fillers. It is a wet strength paper and able to withstand boiling water. Synthetic resins are used for to provide wet strength.

Color-fast papers Colored papers that will not run when wet or fade under bright light.

Commodity Paper A classification for low-quality bond and offset papers.

Colored Kraft Natural or bleached kraft paper to which a dye or pigment has been added.

Condenser Tissue A very thin paper of uniform thickness, good formation, and especially free from conducting particles. Used as a dielectric between the foils of condensers.

Construction Paper

Sheathing paper, roofing, floor covering, automotive, sound proofing, industrial, pipe covering, refrigerator, and similar felts.

Containerboard The paperboard components (linerboard, corrugating material and chipboard) used to manufacture corrugated and solid fiberboard. The raw materials used to make containerboard may be virgin cellulose fiber, recycled fiber or a combination of both.

Copier Paper or Laser Paper Lightweight grades of good quality and dimensionally stable papers used for copying correspondence and documents.

Correspondence Papers Writing papers in attractive finishes, weights or colors.

Corrugated Board Usually a nine-point board after if has passed through a corrugating machine. When this corrugated board is pasted to another flat sheet of board, it becomes single-faced corrugated board; if pasted on both sides, it becomes double-faced corrugated board or corrugated (shipping) containerboard.

Corrugated Medium or Fluting Media or Media The wavy center of the wall of a corrugated container, which cushions the product from shock during shipment (see flute). Media can contain up to 100% post-consumer recycled fiber content without reducing its ability to protect the product.

Cotton Paper or Rag Paper Paper made with a minimum of 25% cotton fiber. Cotton paper is also called rag paper.

Cover Paper Any wide variety of fairly heavy plain or embellished papers, which are converted into, covers for books, catalogs, brochures, pamphlets, etc. Good folding qualities, printability, and durability characterize it.

Creamwove Paper Medium brightness paper now mainly used for computer stationery purposes or school children note books.

Crepe Paper A light weight paper, normally colored, with crinkly finish used for party decoration..

Cut Sheet Paper cut in sheets (letter, legal, A, B or any other standard size) to be used in printer, photocopier, fax machines etc.

D

Damask Paper Paper with a finish that resembles linen.

Decalcomania Paper A type of transfer paper that allows the transfer a printed image to another object such as glass. Also called a decal.

Diazo Base Paper

The process involves coating of paper with Diazo solutions and a coupler. This is exposed to ultra violet rays coming through the image. The final print is developed by making the coating alkaline. In some cases it is developed by ammonia vapor.

Directory Paper A light weight grade of catalog or printing paper with good strength, high opacity and good printability. It is made from a mixture of bleached chemical, semi-chemical, CMP and recycled fiber and used for printing telephone directory.

Document Paper Document paper is paper with a high ageing resistance. It is woodfree but may also contain rags or be fully made from rags and is used for documents that have to be preserved for a longer period.

Drawing Paper Dull finished paper that is of good quality and stable enough to withstand erasing.

Duplex Board Paperboard made with two plies or layers. Normally two layers are formed and joined together at wire part.

Duplex Paper Paper made with two plies or layers. Normally two layers are formed and joined together at wire part.

E

Electrical Grade Paper Strong, pin-hole free paper, sometimes impregnated with synthetic resins and made from unbleached Kraft pulp. Electrical insulating paper must neither contain fillers nor conductive contaminants (metals, coal, etc.) nor salts or acids. Lava stone bars are used on rotor and stator to avoid any metal contamination. Cable papers, that are wound around line wires in a spiral-like fashion, are electrical insulating papers with a particularly high strength in machine direction. Electrical grade papers include cable papers, electrolytic papers and capacitor paper.

End-leaf Paper Strong, fine quality papers, either plain or coated and sometimes colored or marbled used at both ends of a book. Also called sheets.

Envelop Paper The paper made specifically for die cutting and folding of envelopes on high-speed envelop machine.

Esparto Paper The writing and printing paper made from esparto pulp.

Extensible Kraft Very strong virgin Kraft papers which stretches (approximately 6%) more in MD and tears less easily than regular Kraft paper.

Extrusion Coated Board Board that has been covered with a continuous layer of a thermoplastic material, typically polyethylene or polypropylene, by the extrusion coating process i.e.

where a thermoplastic material is melted and forced through a narrow slot onto a moving web of board.

F

Fax Base Paper It is first coated with photo conductive zinc oxide on which images are exposed. Hence electrical conductivity / resistivity is to be controlled to ensure that the image is not conducted through the paper to the other side

Fiberboard Board made from defibrated wood chips, used as a building board.

Filter Paper Unsized paper made from chemical pulp, in some cases also with an admixture of rags, sometimes with a wet strength finish. Filtration rate and selectivity, which are both dependent on the number and the size of the pores, can be controlled by specific grinding of the pulps and creping.

Fine Papers Uncoated writing and printing grade paper including offset, bond, duplicating and photocopying.

Flame Resistant Treatment applied to kraft paper to make it resistant to catching on fire (not fire proof—will char but not burst into flame).

Flocked Paper Paper with a velvet-like, smooth unglazed surface.

Fluorescent Paper Paper coated or surface treated with fluorescent dye to make it glow in dark. Used for labels, posters and decorative application.

Folding Boxboard Single or multi-layer paperboard made from primary and/or secondary fibers, sometimes with a coated front, used to make consumer packaging (cartons).

Form Bond A lightweight commodity paper designed primarily for printed business forms. It is usually made from chemical wood and/or mechanical pulps. Important product qualities include good perforating, folding, punching, and manifolding properties. The most common end use for this grade is carbon-interleaved multi-part computer printout paper, which is marginally punched, cross-perforated, and fanfolded.

Freesheet Paper that is free of mechanical wood pulp, which is true of virtually all fine printing papers.

Fruit Wrapping Paper A lightweight tissue used for wrapping fruit for shipment. Sometimes treated chemically to retard decay of the fruit with which it is in contact.

G

Gasket Board A highly absorbent pulp board, which is chemically treated for use in making gaskets.

Glassine Paper A translucent paper made from highly beaten chemical pulp and subsequently supercalendered.

Glazed Paper Paper with high gloss or polish, applied to the surface either during the process of manufacture or after the paper is produced, by various methods such as friction glazing, calendering, plating or drying on a Yankee drier.

Grade Papers are differentiated from each other by their grade. Different grades are distinguished from each other on the basis of their content, appearance, manufacturing history, and/or their end use.

Granite Paper A paper containing a small percentage of deeply dyed fibers to give a characteristic mottled effect.

Gravure Paper Paper for gravure printing that has very low print roughness and good wettability of gravure inks.

Gray Board A homogeneous board made usually of mixed waste papers with or without screenings and mechanical pulp on a continuous board machine, in thickness less then 1 mm.

Greaseproof Paper A protective wrapping paper made from chemical wood pulps, which are highly hydrated in order that the resulting paper may be resistant to oil and grease.

Green Paper Immature paper which has not been conditioned or had the opportunity to mature naturally.

Groundwood Papers A general term applied to a variety of papers made with substantial proportions of mechanical wood pulp together with bleached or unbleached chemical wood pulps (generally sulfite), or a combination of these, and used mainly for printing and converting purposes.

Gummed Paper The main ingredient in gypsum board is gypsum (calcium sulfate - Ca2SO4), a mineral.. Board is lined with sheet of paper on both sides. This is used for making panel boards for interior partitions, false ceiling etc.

Gypsum Board The main ingredient in gypsum board is gypsum (calcium sulfate - Ca2SO4), a mineral.. Board is lined with sheet of paper on both sides. This is used for making panel boards for interior partitions, false ceiling etc.

H

Handmade Paper A sheet of paper, made individually by hand, using a mould and deckle.

Hanging Paper The raw stock used in making wall paper. The converter usually coats it with a ground coat of clay, and then prints it with any decorative design desired.

Hard Sized Paper Paper treated with high degree of internal sizing.

Heat Seal Paper Paper that has an adhesive coating applied to it that requires heat to activate the adhesion properties.

Heat Transfer Paper The paper used in Thermal transfer printing (Sublimation printing).

Hi-Fi (High Finish) Paper Machine calendered newsprint.

I

Index Paper A stiff, inexpensive paper with a smooth finish. The high bulk but low weight of this paper makes it a popular choice for business reply cards.

Industrial Papers A very general term, which is used to indicate papers manufactured for industrial uses as opposed to cultural purposes. Thus, building papers, insulating papers, wrapping papers, packaging papers, etc. would be considered industrial papers.

Insect Resistant Paper treated with insecticide compounds to make it resistant to insect attack.

Insulating Board A type of board composed of some fibrous material, such as wood or other vegetable fiber, sized throughout, and felted or pressed together in such a way as to contain a large quantity of entrapped or "dead" air. It is made either by cementing together several thin layers or forming a non-laminated layer of the required thickness. It is used in plain or decorative finishes for interior walls and ceilings in thicknesses of 0.5 and 1 inch (in some cases up to 3 inches) and also as a water-repellent finish for house sheathing. Desirable properties are low thermal conductivity, moisture resistance, fire resistance, permanency, vermin and insect resistance, and structural strength. No single material combines all these properties but all should be permanent and should be treated to resist moisture absorption.

Ivory Board High-quality board made in white or colors with a bright, clear appearance, particularly used for visiting cards and similar high-class printed work. Original Ivory Board was and still is made in Holland, although the grade is made in many countries.

J

Japan Paper An imitation of the Japanese vellum paper in which the fibers are very long and have a very irregular formation, giving the surface a characteristic mottled effect. Used for greeting cards, novelties and artistic printing of various types. The real Japanese paper is made from very long native fibers, such as paper mulberry, mitsumata, etc.

Jute Paper Any paper made from jute fiber or burlap waste. The fiber is long and the paper has high strength and good folding properties. The name is becoming misleading because of its application to fiber furnishes which contain little or no jute.

K

Kraft Bag Paper A paper made of sulfate pulp and used in the manufacture of paper bags. It normally has a greater bulk and a rougher surface than the usual kraft wrapping paper.

Kraft liner Paperboard of grammages of 120g and more, generally made from bleached or unbleached sulfate pulp and used as an outer ply in corrugated board.

Kraft Paper A paper of high strength made from sulfate pulp. Kraft papers vary from unbleached Kraft used for wrapping purposes to fully bleached Kraft used for strong Bond and Ledger papers.

Kraft Waterproof Paper A highly moisture resistant paper made of sulfate pulp and treated with moisture repellent material such as paraffin wax or asphalt and used for wrapping purposes.

Kraft Wrapping Paper A group of paper grades made from sulfate pulp using various material and used for general wrapping purposes.

L

Label Paper Mostly one-side coated papers which must be printable in 4-colour offset and gravure printing. These papers are usually suitable for varnishing, bronzing and punching and sometimes also feature wet strength and alkali resistance (See "Wet strength and alkali resistant paper") in order to en-sure the removal of the labels e.g. in the bottle rinsing machines of breweries

Lace Paper A medium weight, well sized paper made from bleached chemical pulp, that has high tensile and tear strength.

Laid Paper Paper that has a laid finish. Commonly used for letterheads and personalized stationery.

Laminated Paper

A paper built up to a desired thickness or a given desired surface by joining together two or more webs or sheets. The papers thus joined may be alike or different; a totally different material, such as foil, may be laminated with paper.

Laminated Linerboard Two or more plies of linerboard adhered to one another for increased structural stability.

Latex Paper A type of paper that has been made from pulp in which a latex emulsion is added. It is used as a coating after the sheet is made or impregnated in to the sheet.

Ledger Paper A strong paper usually made for accounting and records. It is similar to Bond paper in its erasure and pen writing characteristics.

Lens Paper A soft, lightweight, nonabrasive tissue made from bleached pulp. It is used to make wrapping and polishing paper for eyeglasses, camera and other optical lenses.

Light Weight Coated (LWC) Coating applied at 7-10 g/m2 on one or both sides of the paper

Light Weight Paper Papers having a grammage (basis weight) normally less than 40 g/m2.

Lightproof Paper Paper made specifically to stop light transmission.

Linen Paper Paper with a finish that resembles linen cloth.

Linear Paper A watermarked sheet with lines to guide the user.

Liner A creased fiberboard sheet inserted as a sleeve in a container and covering all side walls. Used to provide extra stacking strength or cushioning. Also used as a short hand for "linerboard" or facing."

Linerboard The inner and outer layers of paper that form the wall of a corrugated board.

Litmus Paper An absorbent paper saturated with, litmus, a water-soluble dye extracted from certain lichens. The resulting piece of paper becomes a pH indicator, used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic conditions, the color change occurring over the pH range 4.5-8.3 (at 25°C).

M

Machine Coated aka On Machine Coated Paper coated one side or both side during papermaking.

Magazine Paper Any paper made to be used for printing magazine, books or periodicals etc..

Manifold Paper

A light weight bond paper used for making carbon or manifold copies or for airmail correspondence.

Manila A semi-bleached chemical sulfate paper. Not as strong as Kraft, but have better printing qualities.

Map Paper Paper used for making maps must be subject to minimum change in dimensions with moisture to avoid poor register of colors. Wet strength properties are often demanded.

Marble Paper A type of paper having surface pattern that of marble.

Matrix Paper A bulky, absorbent paper used for making molds for casting printing plates. It must have high compressibility and strength when wet, and become rigid and hard when molded and dried. It is sometimes made by allowing a thin web to wind up on the cylinder of a wet-machine and cutting it off when of the proper thickness.

Matt Finished Paper A dull finish paper.

Mechanical Paper This paper contains mechanical pulp, thermomechanical pulp (TMP) or chemithermo-mechanical pulp (CTMP) and also chemical pulp. The shares of chemical and mechanical pulp vary depending on the application. Highly mechanical papers such as newsprint tend to yellow more rapidly if exposed to light and oxygen than woodfree papers so that they are mainly used for short-lived products. In printing papers the mechanical pulp improves opacity.

Mellow Paper Type of paper that are characteristically soft and have been allowed to mature.

Metalization Base Paper Paper used for very high vacuum deposition. Metals are vaporized at low temperature but very high vacuum and deposited on paper. Base paper is light weight, no conductive particles and no pin holes.

MF Machine finished. Smooth paper calendered on the paper machine.

MG Machine glazed. Paper with a glossy finish on one side produced on the paper machine by a Yankee cylinder.

Millboard A thick, dense, homogeneous board, for book production, made generally from wastepaper, on a special board making machine one sheet at a time. Used in binding case bound books, ledgers etc. as binders’ boards.

Mulberry Paper This term is given to a wide range of actual handmade and "handmade" papers. "Handmade" meaning that is has the rough look of actual handmade paper but it is in fact mass produced by machine.

Many mulberry papers are made from Kozo and other similar fibers. Some in fact

do contain mulberry bark and/or fibers.

It is easy to recognize Mulberry papers as they generally have distinct fibers running through the papers. There are some mulberry papers that have finer fibers that are not as noticeable but a large majority have the easy to recognize large fibers. It is very pretty stuff and can be used in all sorts of crafts applications.

N

Natural Colored Papers or Self Colored Papers Papers where color is that obtained only from wood fibers used to make it. No dye or pigment is added.

Newsprint A paper manufactured mostly from mechanical pulps specifically for the printing of newspaper. Pulp and Paper Product Council provides the following definition for newsprint. A general term used to describe paper between 40 g/m2 and 57 g/m2 generally used in the publication of newspapers. The furnish is largely mechanical wood pulp with some chemical wood pulp.

 

North America

The definition of newsprint used by the PPPC for statistical purposes is as follows:  

GrammageColourCaliperBrightnessAsh ContentSizingSmoothness

40 - 57 grams per square metre;white or slightly coloured;under 100.0 microns (0.00394 inches);less than or equal to 65 ISO;not exceeding 8.0% by weight;unsized or lightly sized;greater than or equal to 2.61 PPS :m (S10) 

Western Europe

Newsprint is that quality of paper used chiefly for the publication of newspapers and which has a basis weight of 40 - 57 grams. Other properties correspond to the

EU harmonized definition, with a brightness up to and including 71 ISO. 

GrammageColourBrightnessAsh contentSmoothnessBulky FactorFurnish 

40 - 57 grams per square metre;white or slightly coloured;59 - 71ISO;not exceeding 10 percent by weight;not exceeding 200 seconds BEKK;below 1.7;not less than 65 percent mechanical pulp by weight. 

Rest of World

Uncoated paper of a kind used for the printing of newspapers, of which not less than 65% by weight of the total fibre content consists of wood fibres obtained by a mechanical or chemi-mechanical process, unsized or very lightly sized, having a surface roughness Parker Print Surf (1 MPa) on each side exceeding 2.5 micrometres (microns), weighing not less than 40g/m2 and not more than 65g/m2.

For PPPC definition of some other common grades of pulp and paper, please visit http://www.pppc.org/en/1_0/index.html

 

O

Oatmeal Paper A paper such as wallpaper to which fine sawdust is added to its stock.

Offset Paper Also known as book paper. General description of any paper primarily suited for offset printing. Can be coated or uncoated. Characterized by strength, dimensional stability, lack of curl and freedom from foreign surface material. Finish can be vellum or smooth.

One Time Carbon Base Paper Unlike regular carbon paper which is used multiple time, one time carbon as name suggest is used only once e.g. government form. The specification on this paper is not as stringent as regular carbon paper.

Onionskin Paper A lightweight, bond-type, thin and semitransparent paper used for duplicate copies of typed matter to save filing space.

P

Packaging Paper A paper or paperboard used for wrapping or packing good.

Paper

A homogeneous sheet formed by irregularly interviewing cellulose fibers. Paperboard

A heavy weight, thick, rigid and single or multi-layer sheet. What differentiates paperboard from paper is the weight of the sheet. If paperboard is very heavy it is called Board. Paper heavier than 150 gram per meter square are normally called Paperboard and paperboard heavier than 500 gram per meter square are called board.

Parchment A sheet of writing material made from the skins of goats or other animals. Vegetable or imitation parchment is made to resemble animal parchment by passing a sheet of unsized, pure fiber paper through a bath of sulfuric acid and then washing it very thoroughly and drying. The acid gelatinizes the surface fibers and the dried surface is grease-proof, has a high wet strength and is very resistant to disintegration by water and many solutions.

Pattern Paper A type of high-strength paper used by designers and tailors for making patterns.

Permanent Paper A paper that can resist large chemical and physical changes over and extended time (several hundred years). This paper is generally acid-free with alkaline reserve and a reasonably high initial strength.

Photographic Paper The base paper used for the production of photographic papers is a dimensionally stable, chemically neutral chemical pulp paper with wet strength properties, that must be free from contaminants. Today papers are coated on both sides with a thin polyethylene film. The cooking prevents chemicals and water entering the paper during development. This also permits shorter rinsing and drying cycles.

Playing Card Stock A stiff board, usually made by pasting sheets of fourdrinier paper, and given a coating which will take a high polish.

Poly Extrusion Paper Paper used for plastic extrusion. Hot melted plastic is applied at the paper surface, so the base paper should be able to withstand heat.

Postcard Board Postcard board is either slightly mechanical or woodfree and calendered.

Post-Consumer Waste Paper Waste paper materials recovered after being used by consumers.

Poster Paper Poster paper is a highly mechanical, highly filled, mostly coloured paper that has been made weather resistant by sizing.

Pre-Consumer Waste Paper Paper recovered after the papermaking process, but before used by a consumer.

Pressure Sensitive Coated Paper Paper coated with a self-adhesive material which in dry form (solvent free) is permanently tacky at room temperature. A bond with the receiving surface may be formed by the application of pressure (e.g. by the finger or hand). A permanent adhesive is characterized by relatively high ultimate adhesion and a removable

adhesive by low ultimate adhesion. Until the time of application, the adhesive surface should be covered by a suitable release coated paper.

Publishing Paper On-machine coated printing paper. Suitable for color printing or toning with low grid number or single color printing. Our products in this category includes: Wood-free printing and writing paper, Ivory wood-free printing and writing paper.

Pulp Board Also known as Printers’ Board, this grade is made from a single web of pulp on a paper making machine, and is produced in various substances. Used for index cards and other general products, these boards may be white or colored.

Pyroxylin Paper Paper coated with pyroxylin lacquer to make it water resistant and glossy.

R

Rag Paper Today rag paper is mostly made from vegetable fibres consisting of cellulose, such as cotton, linen, hemp and ramie. Rags are the most precious raw material for the papermaker. Rag papers and rag-containing papers with admixtures of chemical pulp are used for banknotes, deeds, documents, books of account, maps and copperplate engravings and as elegant writing papers. They are also used for special technical applications.

Recovered Paper Paper recovered for recycling into new paper products. Recovered paper can be collected from industrial sources (scraps, transport packaging, unsold newspapers...) or from household collections (old newspapers and magazines, household packaging).

Recovered Paper Grades Recovered paper sorted by types in order to be recycled by paper mills. Specific grades are used by paper mills, in order to produce different types of paper and boards.

Release Paper Release paper is used to prevent the sticking of glue, paste or other adhesive substances. Coating paper with silicone yields papers with a surface that prevents adhesion of most substances. Application: cover material for self-adhesive papers or films, e.g. in label production.

Rice Paper A common misnomer applied to lightweight Oriental papers. Rice alone cannot produce a sheet of paper. Rice or wheat straw is used occasionally mixed with other fibers in paper making. The name may be derived from the rice size (starch) once used in Japanese papermaking

Roofing Paper Board that is impregnated with tar, bitumen and/or natural asphalt.

S

Sack Paper High strength kraft paper used for paper sacks.

Safety Paper Papers with a special protection against abusive imitation. The safeguards are used during the production of the paper. It is also known as antifalsification paper.

Sanitary Papers The group of sanitary papers includes cellulose wadding, tissue and crepe paper, made from waste paper and/or chemical pulp - also with admixtures of mechanical pulp. As a consequence of the importance of tissue today, this name is now used internationally as a collective term for sanitary papers. These grades are used to make toilet paper and numerous other sanitary products such as handkerchiefs, kitchen wipes, towels and cosmetic tissues.

Sanitary Tissue Paper Tissue is a sanitary paper made from chemical or waste paper pulp, sometimes with the admixture of mechanical pulp. It has a closed structure and is only slightly creped. It is so thin that it is hardly used in a single layer. Depending on the requirements the number of layers is multiplied. Creping is made at a dryness content of more than 90 %. The dry creping (unlike with sanitary crepe papers) and the low grammage of a single tissue layer result in a high softness of the tissue products. For consumer products it is normally combined in two or more layers. The flexible and highly absorbent product [is mainly produced from chemical pulp and/or DIP - sometimes also with admixture of groundwood pulp] can also be provided with wet strength. Applications: facial tissues, paper handkerchiefs, napkins, kitchen rolls, paper towels, toilet paper.

Security paper Paper which includes identification features such as metallic strips and watermarks to assist in detecting fraud and to prevent counterfeiting.

Self Adhesive paper Used essentially for labeling purposes, this grade has a self-adhesive coating on one side and a surface suitable for printing on the other. The adhesive is protected by a laminate which enables the sheet to be fed through printers or printing machines, the laminate subsequently being stripped when the label is applied

Self Contained paper A self imaging carbonless paper that does not need the use of any other carbonless stock to make an image appear. When pressure is applied, it causes the chemicals on the front of the sheet to create an image. This paper is used in ribbonless impact printers.

Silicon Treated Paper A strong paper with a glazed finish that is treated with silicones on one side. This produces a release quality that is necessary for the liners used for pressure sensitive paper.

Single Faced Corrugated Board Corrugated fiberboard consisting of two layers, one of fluted paper and one of facing.

Sized Paper

Sizing reduces the water absorbency of the paper and thus creates the condition for the writability with ink. Sized paper is also used for many other purposes (printing, coating, gluing, etc.), and the sizing agents must fulfil a wide range of tasks. For instance, they control the water absorbency and increase the ability to retain water and ink (pick resistance).

Solid Fiberboard Collective term for all solid board grades.

Specialty Paper The group of specialty papers comprises numerous paper grades, each characterized by particular properties. These properties often require special raw materials.

Spinning Paper Paper with a particularly high tensile strength in the machine direction; suitable for being spun into yarn or string.

Stamp Paper Paper used for printing postal stamp. Paper should have good printability, high strength, good glueability, permanence and high dimensional stability.

Strawboard Board made from partially cooked straw, bagasse or grass or a mixture of these.

Suede Paper Paper that has a velour finish.

Supercalendered Paper A type of uncoated paper that has been supercalendered to obtain a smooth surface and high gloss than the machine-finished paper. It is used for printed advertising material, catalogues, and magazines.

Surface-Sized Paper that has been treated with starch or other sizing material at the size press of the paper machine. This term is used interchangeably with the term "tub-sized", although tub-size more properly refers to surface sizing applied as a separate operation where the paper is immersed in a tub of sizing (starch or glue), after which it passes between squeeze rolls and is air dried.

Super Art Paper Highest grade of art paper with double or triple coating. Coat weight of 25g/m2 per side, with gloss level over 80%, surface feels smooth and shiny, superb printing quality, suitable for high-quality picture books, product catalogues, and refined printing products..

Synthetic Fiber Paper Papers made from synthetic fibers such as polyamide and polyester, from viscose staple fiber or sometimes also with fillers. The fibers are mainly held together by binders. The durable synthetic fiber papers are used for maps and highly important documents such as driving licenses or vehicle registration books.

T

Tag Paper

A heavy utility grade of paper used to print tags, such as the store tags on clothing. Tag paper must be strong and durable, yet have good affinity for printing inks.

Tea Bag Paper Used to pack tea leaves. Paper should not have any impurities. It should have high liquid permeability and should withstand boiling water.

Technical Paper Variety of medium-grammage papers used in different industrial purposes.

Testliner Mainly produced from waste paper used as even facing for corrugated board or as liner of solid board. They are often produced as duplex (two-layer) paper. The grammage is higher than 125 gsm.

Text Paper Text papers are defined as fine, high quality uncoated papers. Typically, they are made in various colors, with numerous textures and a variety of surface finishes. Text papers are made from high-grade bleached wood pulp, cotton fibers, or tree-free pulp such as bamboo. Recycled sheets include high quality recycled waste paper and post-consumer waste pulp, in addition to bleached wood pulp, tree-free pulp or cotton fibers.

Thermal Paper Any paper with a heat-sensitive coating on which an image can be produced by the application of heat.

Thin Paper Includes carbonizing, cigarette, bible, air mail and similar papers.

Tissue A low weights and thin sheet. Normally a paper sheet weighing less than 40 gram per meter square is called tissue.

At-Home products: Also known as Consumer Products, these are the tissue products you purchase in the grocery store and convenience store for use in your home and include toilet paper and facial tissue, napkins and paper towels, and other special sanitary papers.

Away-from-Home products: Also known as Commercial & Industrial Tissue, these are the products that serve markets such as hospitals, restaurants, businesses, institutions, and janitorial supply firms.

Specialty: These types of tissue papers are often high-end, decorative papers that are glazed, unglazed, or creped, and include wrapping tissue for gifts and dry cleaning, as well as crepe paper for decorating.

Facial tissue: The class of soft, absorbent papers in the sanitary tissue group. Originally used for removal of creams, oil, and so on, from the skin, it is now used in large volume for packaged facial tissue, toilet paper, paper napkins, professional towels, industrial wipes, and for hospital items. Most facial tissue is made of bleached sulfite or sulfate pulp, sometimes mixed with bleached and

mechanical pulp, on a single-cylinder or fourdrinier machine. Desirable characteristics are softness, strength, and freedom from lint.

Translucent Drawing Paper A paper suitable for drawing office use; sufficiently translucent for an image on it to be reproduced by processes using transmitted light and for a design to be traced on it from an original placed beneath it. Such processes include blueprint and diazo.

Transparent Paper Extended and particularly careful grinding of high quality fibres (hard chemical pulps, rags) yields a raw material permitting the production of transparent paper.

Treated Paper Papers which have functional characteristics added through special treatment. Among the most common are insect resistant, mold resistant, clay coated, and flame retardant.

Twisting Paper A paper of high tensile strength in the machine direction which is cut into narrow widths and spun or twisted into yarn or twine.

U

Union Kraft A packaging material comprising two layers of Kraft paper bonded together by means of a laminate that is resistant to the transmission of water in liquid or vapor form. E.g. bitumen or plastic.

Unglazed Paper Un-calendered paper.

Un-sized Paper A paper which has not been sized.

V

Vaporproof Paper Paper or paperboard that has been chemically treated or laminated with vapor barrier so that it will resist the passage of gases or vapor through it. It is typically used for food packaging.

Varnish-Label Paper Paper made from bleached chemical pulp to be converted in to label which are subsequently varnished.

Vegetable Parchment Paper that has acquired, by the action of sulfuric acid, a continuous texture. It offers high resistance to disintegration by water and grease.

Vellum Paper (1) Paper finish that exhibits a toothy surface similar to eggshell or antique and is relatively absorbent for fast ink penetration.

(2) A high-grade paper made to resemble parchments originally made from calf’s skin. (3) Social and personal stationery is often called vellum.

Velour Paper A paper with a velvet like finish, produced by flocking the surface with fine bits of rayon, nylon, cotton, or wool, it is sometimes embossed in various patterns.

Velvet Finish Paper Paper with a smooth finish without any gloss, simulating velvet.

Verdol Paper A high strength rigid paperboard or pressboard made typically from jute fibers. It is also known as jacquard board.

Vulcanizing Paper Paper made specifically for treatment with zinc chloride (ZnCl2) and sulfuric acid (H2SO4) to gelatinize the surface cellulose. Vulcanizing converts the paper in to a hard, dense and tough sheet which is used in electrical insulation, luggage, mechanical assemblies and building material.

W

Wadding A single or multi-layer loosely matted fiber pad made from chemical pulp and used in packaging, thermal insulation and /or acoustical applications. It is also used in diaper and as absorbent material in other sanitary products.

Wall Paper A paper used for wall covering. Also known as hanging paper.

Washi Washi comes from wa meaning Japanese and shi meaning paper, and the term is used to describe paper made by hand in the traditional manner.  Washi is commonly made using fibers from the bark of the gampi tree, the mitsumata shrub, or the paper mulberry, but also can be made using bamboo, hemp, rice, and wheat.

Water-Color Paper A medium weight, hard sized, coarse surface paper, suitable for painting with water based colors.

Water Finished Paper A high glazed paper produced by moistening the sheet with water or steam during calendering.

Water Resistant Paper Paper which has been impregnated, coated or laminated to resist the penetration of water.

Waterleaf A paper with little or no sizing, like blotter, making it very absorbent If dampening is desired, this paper can be sprayed with an atomizer.

Waxed Paper Nearly woodfree papers that are impregnated with paraffin, wax or wax/paraffin/plastic mixtures. With the appropriate saturation agent and process

the product may be tailored for specific applications, e.g. packaging of bread or sweets or wrapping razor blades.

Wet Strength Paper A chemically treated paper strong enough to withstand tear, rupture or falling apart when saturated with water.

White Top Liner A two-ply sheet comprised of one bleached and one unbleached layer.

Willesden Paper Paper made waterproof by immersing in a bath of cuprammonium hydroxide, washing and drying. The treatment partially dissolves and gelatinizes the surface and the final paper is parchment-like, tough, waterproof, rotproof and distasteful to insects. It is used for roof covering and insulating purposes.

Wipes or Wiper Folded absorbent tissue used for cleaning purpose.

Wood Free Paper The paper made without using mechanical pulp.

Wove The Paper having a uniform surface and no discernible marks. Soft, smooth finish, most widely used writing, printing, book and envelope paper. Relatively low opacity, brightness and bulk.

Wrapper The materials, consisting usually of paper or paperboard, sometimes with treatment for moisture barrier properties, which are used to protect the roll or pile form damage.

Writing Paper Uncoated paper that is suitable for writing with ink on both sides. The writing must neither bleed nor strike through. Writing paper is always fully sized (See "Sized paper") and also suitable for printing. It can be woodfree or mechanical, depending on the intended purpose. The admixture of fillers makes it less translucent.

X

Xerographic Paper Copying paper used on photocopier made by Xerox.

Y

Yellow Pages Used for telephone directory advertising. Paper used for this needs to have high bulk (1.1 to 1.2), high tensile strength of about 2 kg/15 mm in MD and good opacity (90%) so that the fine print made on thin paper like 40 gsm would be readable on both side. Excellent reel build up is required for smooth feeding during printing. This requires every uniform profile of bulk, gsm, caliper, moisture etc.

Physical Properties

Basis Weight or Grammage   The basis weight, substance or grammage is obviously most fundamental property of paper board. The Basis weight of paper is the weight per unit area. This can be expressed as the weight in grams per square meter (GSM or g/M2), pounds per 1000 sq. ft. or weight in Kgs or pounds per ream (500 sheets) of a specific size. Paper is sold by weight but the buyer is interested in area of paper. The basis weight is what determines, how much area the buyer gets for a given weight. e.g. if basis weight is 50 g/m2, for every 1 kg weight, the buyer gets 20 m2. When the

basis weight is expressed as ream weight, it tells the buyers how many reams he/she getting for a given weight.

  For papermaker basis weight is important from point of view of production rate. For a given machine deckle and machine speed, the production rate per day in MT will be = Machine Deckle (m) * Machine Speed (m/min) * Basis Weight (g/M2) * 1440/1000000.

  Papermaker always strive to get all desired properties of paper with minimum possible basis weight.

  All paper machines are designed to manufacture paper in a given basis weight range. Tighter the range and more efficient will be the machine. The standard procedure of measuring basis weight is laid out in  TAPPI T 410, SCAN P6, DIN53104 & ISO: BSENISO536

 

Typical Grammage Values

Grade g/m2

Newsprint 40 - 50

Cigarette Tissue 22 - 25

Bond 60 -90

Paperboard 120 - 300

Accepted trade tolerance +/- 5%

Bulk Bulk is another very important parameter of paper particularly for printers. Bulk is a term used to indicate volume or thickness in relation to weight. It is the reciprocal of density (weight per unit volume). It is calculated from caliper and basis weight. Bulk (cubic centimeter/g) = Thickness (mm)* Basis Weight (g/m2) * 1000. Sheet bulk relates to many other sheet properties. Decrease in bulk or in other words increase in density makes the sheet smoother, glossier, less opaque, darker, lower in strength etc.

  High bulk is desirable in absorbent papers while lower bulk is preferred for printing papers particularly bible paper, dictionary paper etc.

  Book Bulk: Book bulk is defined as the overall thickness in mm of a given number of paper sheets. The bulking number is defined as number of sheets required to bulk 25 mm or approximately 1". The standard procedure of measuring book bulk is laid out in TAPPI T 500, SCAN P7 DIN53105, ISO 534, BS: EN ISO20534

 

Typical Thickness Values

Grade μm

Newsprint 60 - 80

Office/Business Paper 105 - 110

Blotting Paper (230g/m2) 540 - 590

Tracing Paper (90g/m2) 78

Label Paper (79g/m2) 63

Tissue(28g/m2) 125

Accepted trade tolerance +/- 10%

Caliper or Thickness   For a given basis weight, thickness determines how bulky or dense paper is. A well beaten/refined pulp, short fiber pulp such as hard wood or straw pulp, highly filled or loaded paper will show lower thickness for given basis weight. Thickness or Caliper of paper is measured with a micrometer as the perpendicular distance between two circular, plane, parallel surfaces under a pressure of 1 kg./ CM2. Uniform caliper is for good roll building and subsequent printing. Variations in caliper, can affect several basic properties including strength, optical and roll quality. Thickness is important in filling cards, printing papers, condenser paper, saturating papers etc.

  The standard procedure for thickness measurement is explained in TAPPI T 411.

Curl Paper curl can be defined as a systematic deviation of a sheet from a flat form. It results from the release of stresses that are introduced into the sheet during manufacture and subsequent use.   Paper curl has been a persistent quality issue and is increasingly important for paper grades being subjected to high speed printing, xerography and high precision converting processes.   There are three basic types of curl, mechanical curl, structural curl and moisture curl. Mechanical curl develops when one side of the paper is stretched beyond its elastic limits. One example of this is the curl in the sheet which forms near the centre of a roll. Structural curl is caused by two-sidedness in the sheet, that is a difference in the level of fines, fillers, fiber area density or fiber orientation through the sheet thickness. Moisture curl can develop when the paper sheet is being offset printed. One side of the sheet may pick up more moisture than the other, the higher moisture side releases the built in drying strains and the paper will curl towards the drier.   For more details on Curl, please read Curl Basics by Chuck Green  

The standard procedure for curl measurement are explained in TAPPI T 466 & T520

  Dimensional Stability

  Cellulose fibers (main constituent of paper) swell in diameter from 15 to 20% from dry condition to saturation point. Since most of the fiber in paper sheet are aligned in the machine run direction, absorption and de-absorption of moisture by paper causes the change in CD dimension. Such changes in dimension may seriously affect register in printing processes and interfere with the use of such items as tabulating cards. Uneven dimensional changes cause undesirable cockling and curling. Dimensional changes in paper originate in the swelling and contraction of the individual fibers. It is impossible to be precise about the degree of this swelling because paper-making fibers differ considerably in this property, and because the irregular cross-section of fibers creates difficulty in defining diameter. Change that occurs in the dimensions of paper with variation in the moisture content is an important consideration in the use of paper. All papers expand with increased moisture content and contract with decreased moisture content, but the rate and extent of changes vary with different papers.

  Dimensional stability of paper can be improved by avoiding fiber to absorb moisture. Well sized papers have better dimensional stability.

For more details on Dimensional Stability, please read Dimensional Stability Notes by Chuck Green

Typical Values

Grade MD (%) CD (%)

Carbonless Paper 0.050-0.150 0.200-0.400

Bond Paper 0.100-0.200 0.200-0.400

Coated Art Paper (under 200 g/m2)

0.090-0.150 0.150-0.350

Gasket Paper 0.400-1.000 0.500-1.100

Formation   Formation is an indicator of how uniformly the fibers and fillers are distributed in the sheet. Formation plays an important role as most of the paper properties depend on it. A paper is as strong as its weakest point. A poorly formed sheet will have more weak and thin or thick spots. These will affect properties like caliper, opacity, strength etc. Paper formation also affects the coating capabilities and printing characteristics of the paper.

  There is no standard method or unit to express formation. It is a relative or subjective evaluation.

Friction

  Friction is the resisting force that occurs between two paper or paperboard surfaces in contact when the surfaces are brought to slide against each other. This property is measured as a coefficient of friction, which is the ratio of the frictional force, to a force acting perpendicular to the two surfaces.   Two components of friction can be measured, these being static and kinetic friction. Static friction is the force resisting initial motion between the surfaces and kinetic friction is the force resisting motion of the two surfaces sliding against each other when already sliding at a constant speed.   Measurement of the coefficient of friction has applications in packaging where a high coefficient will indicate that containers such as sacks, bags and paperboard containers will resist sliding in unit loads or on packaging lines. This property is also important in printing papers, since a specific coefficient of friction is needed so that individual sheets will slide over each other, otherwise double press feeding may result.   There are two methods of measuring Co-efficient of friction of paper. One, which uses Incline Plane is explained in TAPPI T 548 & T815, the second method, which uses Horizontal Plane is explained in TAPPI T 549 & T816.

 

Typical Co-efficient of Friction Values Using Horizontal Plane Method

Grade Static Friction Kinetic Friction

Office/Business Paper 0.50-0.65 0.35-0.5

Silk Coated Paper 0.45-0.55 0.30-0.45

Gloss Coated Paper 0.40-0.50 0.30-0.40

  Machine and Cross Direction

  In paper machine approach flow system, when stock passes through pressure screen, the fibers are oriented lengthwise. If the stock velocity from headbox slice is equal or less than wire speed, fibers which are already oriented lengthwise, will align in the direction of wire run. Fiber alignment can be altered to some extent if stock velocity is less than wire speed. So all papers have a definite grain direction due to greater orientation of fibers in the direction of paper machine run. This grain direction is known as machine direction. The cross direction is the direction of paper at right angles to the machine direction. Some of the properties vary with the MD and CD and hence the values are reported in both the directions. The sheet which have all relevant properties same or almost same in both direction are known as 'square sheet'.  

While sheeting the paper, machine and cross direction are to be kept in mind and the sheet cutting to be done to suit the end use requirements. E.g. 1. All printing papers are to be cut in long grain (The biggest dimension in the grain direction). 2. Book papers fold better and the book stays open better if the sheets are out so that the machine direction runs up and down the pages. 3. Wrap around labels for metal cans and bottles are to be cut with the machine direction vertical to obtain greater flexibility about the can. Long grain and Short grain : The sheet is in long grain if the larger dimension is parallel to grain (MD) direction. The sheet is said to be in short grain if the larger dimension is parallel to cross direction (CD).   There is no sure way to determine the MD or CD of a sheet but one crude method which work is; cut a strip of about 1" wide and 2" long paper and moist it. Put this moist sheet on a smooth surface or hand. As sheet will dry it will curl. The direction of curl is CD as paper contract in CD more than MD while drying.

Moisture Almost all grade of paper has some percentage of moisture. Moisture in paper varies from 2 - 12% depending on relative humidity, type of pulp used, degree of refining and chemical used. Most physical properties of paper undergo change as a result of variations in moisture content. Water has the effect of plasticizing the cellulose fiber and of relaxing and weakening the inter-fiber bonding. The electrical resistance and the dielectric constant of paper both vary with moisture content. The absorption and reflectance of certain bands of infrared and microwave radiation by paper are affected by its moisture content. The amount of water present in a sheet of paper is usually expressed as a percent. The amount of water plays an important role in calendaring, printing and converting process. Moisture control is also significant to the economic aspect of paper making. Water comes free. Poor moisture control can adversely affect many paper properties.

  The absolute moisture content is expressed as a % of the paper/paperboard weight. The sample is generally not conditioned while doing this test. The standard procedures are laid out in TAPPI T 412 and ISO 287, SCAN P4

 

Typical Moisture Values

Grade %

Newsprint 7.5 - 9.5

Office/Business Paper 4 -4.5

Marketing Wood Pulp 10

Printing Paper 6 -7

Tissue 2 - 7

Accepted trade tolerance +/- 10%

Smoothness

  It is most important parameter for printer. Smoothness is concerned with the surface contour of paper. It is the flatness of the surface under testing conditions which considers roughness, levelness, and compressibility. In most of the uses of paper, the character of the surface is of great importance. It is common to say that paper has a "smooth" or a "rough" texture. The terms "finish" and "pattern" are frequently used in describing the contour or appearance of paper surfaces. Smoothness is important for writing, where it affects the ease of travel of the pen over the paper surface. Finish is important in bag paper as it is related to the tendency of the bag to slide when stacked. Smoothness of the paper will often determine whether or not it can be successfully printed. Smoothness also gives eye appeal as a rough paper is unattractive.

  Smoothness (Bekk Method): This test is an indirect measure of paper smoothness when it is under moderate pressure( 100 kPa). The standards test procedure is described in TAPPI T 479.

  Roughness (Sheffield Method): This test is an indirect measure of paper smoothness or roughness. It is a measurement of air flow between the specimen (backed by flat glass on the bottom side) and two pressurized, concentric annular lands that are impressed in to the sample from top. The standards test procedure is described in TAPPI T 538.

  Roughness (Print-surf Method): Very similar to Sheffield methods. The standards test procedure is described in TAPPI T 555.

 

Typical Smoothness Values

Grade Parker Print Surf (μm) Bendtsen (mls/min)

Newsprint (40 - 49g/m2) 2.6-4.5 80-140

Stationery (45-135g/m2) 0.8-2.6 50-300

Business Papers (80g/m2)   100-300

Test Liner (186 g/m2)   1750

Temperature and Humidity: Conditioning of Paper   As explained above it is important to control the moisture content of paper and keep it stable during converting operation. To keep moisture content constant, it is important that paper is conditioned. Conditioning of paper is also of important in many printing and converting operations. In addition to the effect of moisture content on physical properties, it also determines the build up of static of the paper sheet subjected to pressure and to friction. The tendency for paper to develop static becomes greater with increasing dryness. Cellulose fibers are hygroscopic i.e. they are capable of absorbing water from the surrounding atmosphere. The amount of absorbed water depends on the humidity and the

temperature of the air in contact with the paper. Hence, changes in temperature and humidity, even slight changes, can often affect the test results. So, it is necessary to maintain standard conditions of humidity and temperature for conditioning.

Wire side and Felt side   Also referred as wire side and top side. The side which is in contact with the paper machine wire during manufacturing is called the wire side. The other side is top side. Before a thin layer of fibers deposit on machine wire, fines and fillers drain out hence wire side has less fines and fillers compared to top side. Certain properties such as smoothness, texture and ink absorbency differ between wire and felt side and it is customary to measure these properties on both sides. This difference of properties on two sides of paper is known as two-sidedness. Highly filled or loaded or paper made from short fiber pulp will show higher two-sidedness.

  In case of paper to be printed on one side only, best results are obtained by printing on felt side. Postage stamps are printed on wire side and then gummed on felt side, where the smoothness is helpful for attaining an even application.

  Wire side and top side described above are in reference to single ply paper. In case of multi-ply paper/board, every ply will have wire side and top side. The top side of top most layer will be top side and wire side of bottom most layer is wire side of multi-ply board. Different type of fibers, fillers and chemicals are used in different layers for techno-economical reasons.

  The standards procedure is described in TAPPI T 455

Optical Properties

Brightness, Whiteness and Color   Brightness may or may not add much value to the 'useful' properties of the paper but it is the most important selling feature. It is a bragging right every paper manufacturer want to have that he/she produces most bright paper.

  Brightness is defined as the percentage reflectance of blue light only at a wavelength of 457 nm. Whiteness refers to the extent that paper diffusely reflects light of all wave lengths throughout the visible spectrum. Whiteness is an appearance term. Colour is an aesthetic value. Colour may appear different when viewed under a different light source. Brightness is arbitrarily defined, but carefully standardized, blue reflectance that is used throughout the pulp and paper industry for the control of mill processes and in certain types of research and development programs. Brightness is not whiteness. However, the brightness values of the pulps and pigments going into the paper provide an excellent measure of the maximum whiteness that can be achieved with proper tinting. The

colour of paper, like of other materials, depends in a complicated way on the characteristics of the observer and a number of physical factors such as the spectral energy distribution of the illuminant, the geometry of illuminating and viewing, the nature and extent of the surround and the optical characteristics of the paper itself.

  Brightness is measured with two different standards - TAPPI/GE and ISO. Though there is correlation, ISO brightness of a sample is usually lower by 1-1.5 units over GE brightness. The standards are as per Tappi T 452.

  Colour is related to perception and therefore measured or specified in terms of color space. A commonly used system is the CIE L,a,b system. This is based on the idea of color opposites.

  L - measure of luminance and varies from 100 for perfect white to 0 for perfect black.a - redness to greenness.b - yellowness to blueness.

  Whiteness is the extent to which paper diffusely reflects light of all wavelengths throughout the visible spectrum i.e. the magnitude & uniformity of spectral reflectance measured as the percent light reflectance for the whole wavelength range. The procedural standards for the measurement of whiteness are explained in ISO 11475.

 

Typical Brightness Values

Grade % ISO

Newsprint 62-65

Fully Bleached Pulp 90

Office/Business Paper 80-95

Bond 70-92

Coated Paper 85-90

 

American Forest & Paper Association  (AFPA) Brightness Quality Levels

Level % TAPPI

Premium 88.0 & above

No. 1 85.0 - 87.9

No. 2 83.0 - 84.9

No. 3 79.0 - 82.9

No. 4 73.0 - 78.9

No. 5 72.9 & Below

 

Color The quality of light given off by a sheet as described by its hue (tint), saturation (strength), and value (darkness or lightness).  A whiter sheet reflects equal amounts of red, green, and blue light - the entire visual spectrum.  While most balanced white sheets have a slightly yellowish cast, most people will perceive a sheet with a slightly blue tint to be whiter.

Fluorescence Fluorescence measures the amount of fluorescent whitening agent present in the paper. Optical brightening agent absorbs UV light and re-emits it as visible blue light. Under lighting with a UV component this makes the paper appear more blue and brighter. All high white grades have high levels of optical brightener. Less than 5 fluorescence indicates very little optical brightener is present.  

Gloss It is the specularly and diffusely reflected light component measurement against a known standard. Gloss is important for magazine advertisements printing . The level of gloss desired is very dependent on the end use of the paper. Gloss and smoothness are different properties and are not dependent on each other.

  Gloss is the specular reflection of light, which is reflected at an equal and opposite angle. Normally measured at 75° or 20°. Generally, gloss of unprinted sheet/ board is measured at 75° (except for cast coated papers). Printed and varnished surfaces are measured at 60° angle. The standard procedures are laid out in TAPPI T 480.

 

Typical Gloss Values

Grade Gloss at 750

Uncoated Printing Paper 4-6

Matt Coated 10-30

Silk Coated 25-50

Art Coated 65-86

    Opacity

  Opacity is the measure of how much light is kept away from passing through a sheet. A perfectly opaque paper is the one that is absolutely impervious to the passage of all visible light. It is the ratio of diffused reflectance and the reflectance of single sheet backed by a black body. Opacity is important in Printing Papers, Book Papers, etc. The opacity of paper is influenced by thickness, amount and kind of filler, degree of bleaching and coating etc.

  Opacity is measured as the percentage of light absorbed by a sheet of paper. Important in book printing where both sides of paper are printed. The procedural standards are explained in ISO 2471 and TAPPI T425.

 

Typical Diffuse Opacity Values

Grade Diffuse Opacity %

Newsprint (40-49 g/m2) 90-94

Stationery (50-100 g/m2) >88

Tracing Paper (60-110 g/m2) 25-40

 

Strength Properties

Bursting Strength   Bursting strength tells how much pressure paper can tolerate before rupture. It is important for bag paper.

  Bursting strength is measured as the maximum hydrostatic pressure required to rupture the sample by constantly increasing the pressure applied through a rubber diaphragm on 1.20 - inch diameter (30.5 mm) sample. The standards procedure is described in TAPPI T 403.

  Bursting strength depends on basis weight of paper. To normalized the bursting strength for various paper, bursting strength is reported as Burst Index = Bursting Strength (kPa)/ Grammage (g/m2) or Burst Factor = Bursting Strength ( g/cm2)/ Grammage (g/m2) or Burst Ratio = Bursting Strength ( lb/inch2)/ Basis Weight (lbs/ream)

 

Typical Bursting Strength Values

Grade KPa

Coated Paper (130 g/m2) 200-300

Coated Paper (250 g/m2) 300-650

Bond Office/Business Paper (100 g/m2) 250-300

Carbonless Paper (50-60 g/m2) 150-200

Bleached Kraft (60 g/m2) 210-260

Test Liner (186 g/m2) 250-475

Compressibility

  The reduction in thickness under compressive forces or pressure. It influences the ability of paper to change its surface contour and to conform to and make contact with the printing plate or blanket during printing impression. This is highly relevant in gravure and letterpress printing. Compressibility is measured as a ratio of roughness under two different standard pressures in a Parker Print Surf tester.

Folding Endurance (Double Folds)   Folding endurance is the paper's capability of withstanding multiple folds before it breaks. It is defined as the number of double folds that a strip of 15 mm wide and 100 mm length can withstand under a specified load before it breaks. Folding endurance has been useful in measuring the deterioration of paper upon aging. It is important for printing grades where the paper is subjected to multiple folds like in books, maps, or pamphlets. Fold test is also important for carton, box boards, ammonia print paper, and cover paper etc. High folding endurance is a requirement in Bond, Ledger, Currency, Map, Blue Print and Record Papers. Currency paper has highest folding endurance (>2000). Long and flexible fibers provide high folding endurance.

  The procedural standards for measuring Folding Endurance using MIT tester are explained in TAPPI T 511.

  Hardness

  The degree to which paper will resist indentation by some other material such as a stylus, pen or printing plate. Hardness is measured with the help of Bendtsen smoothness tester with load on the measuring head.

  Ply Bond/ Scott Bond

  The Internal Bond Strength of paper or paperboard (also known as Ply Bond Strength or Z Directional Strength) is the ability of the product to resist splitting when a tensile load is applied through the paper’s thickness i.e. in the Z direction of the sheet.   The internal bond strength is often determined on high tack coated Fine papers, offset papers and for multiply papers (e.g. top liner of carton board or abrasive paper used to form belts in grinding machines). One particular application is determining the ply bond strength of “Peelable”    The interlayer strength of the paperboard, measured on Scott Bond Tester, expressed in J/m2. The standard procedures are explained in TAPPI T 403 & T833 & SCAN P80. In paper, it is a measure of the internal strength of the sheet.

 

Typical Scott Bond Values

Grade J/M2

Cover Paper 125-230

Offset Paper 240-290

Xerographic Paper 220-400

Coated Cover Paper 200-315

Coated Text 240-365

 

Resiliency   The ability of paper to recover its original thickness and surface contour after release of the compressive forces of printing nips.

  Stiffness

  Stiffness is the measure of force required to bend a paper through a specified angle. Stiffness is an important property for box boards, corrugating medium and to certain extent for printing papers also. A limpy and flimsy paper can cause feeding and delivery problems in larger sheet presses. A sheet that is too stiff will cause problems in copier machines where it must traverse over, under, and around feed rollers. Bond papers also require certain stiffness to be flat in typewriters etc.

  Stiffness (Taber): A measure of flexural rigidity, Stiffness is the bending moment (g-cm or mNm) required to deflect the free and of a 1.5 in wide vertically clamped sample 15° from its center line when load is applied 50 mm away from the clamp; measured in MD & CD.

  The procedural standards are explained in Tappi T 489 and ISO 2491.

Droop Rigidity CD: Droop rigidity measures the stiffness of the paper or board, more often applied to lighter weight grades. CD refers to cross direction, and MD to machine direction, Droop rigidity is higher in the machine direction. The higher the value the stiffer the paper.

Droop Rigidity MD: Droop rigidity measures the stiffness of the paper or board, more often applied to lighter weight grades. CD refers to cross direction, and MD to machine direction, Droop rigidity is higher in the machine direction. The higher the value the stiffer the paper.

Bending Resistance/ Stiffness (Lorentzen & Wettre): It is a measure of the resistance offered to a bending force by a rectangular sample, expressed in mN (milli Newtons). The standards are as per Tappi T 556.

Typical Bending Values

Grade Bending Moment Stiffness (mNm)Resonance Length Stiffness (mNm)

  MD CD MD CD

Coated Paper (135 g/m2) 65 45 1043 721

Office/Business Paper (80 g/m2)

39 17 493 160

Carbonless Paper (46 g/m2) 7.5 3.3 76 34

  Stretch (Elongation)

  Stretch is the amount of distortion which paper undergoes under tensile stress. Stretch elongation is usually expressed, as percent stretch to rupture. Stretch can be related to the paper's ability to conform and maintain conformance to a particular contour, e.g. Copier paper, multicolor offset printing papers, liquids packing cartons base papers etc. It is an important property in sack kraft papers which are used for cement bags etc. Stretch is higher in cross direction than machine direction.

  The tensile strain developed in a test sample at maximum tensile strength before rupture, measure as the % increase in the length of the sample to the original length. The procedural standards are explained in TAPPI T 494

  Surface Strength (Wax Pick No.)

  A measure of the surface strength of the sample or surface resistance to picking. Pick occurs due to poor internal bonding strength, making it susceptible to adherence to grade wax sticks (Dennison). This test is valid only for uncoated board or paper. For Coated stock IGT pick test is applicable.   Acceptable pick level for uncoated papers =>Wax  #6 Acceptable pick level for Gloss papers =>Wax  #11   IGT is a measurement of the surface strength of the paper. A tacky ink is applied to sample of the paper at an increasing speed. As the speed increases the peeling force applied to the paper also increases and the speed at which the fibers begin to be pulled from the sheet is recorded as the IGT. A high IGT (>300) indicates a strong surface strength suitable for demanding offset applications.

Tearing Resistance   Tearing resistance indicates the behavior of paper in various end use situations; such as evaluating web runnability, controlling the quality of newsprint and characterizing the toughness of packaging papers where the ability to absorb shocks is essential. fiber length and inter-fiber bonding are both important factors in tearing strength. The fact that longer fibers improve tear strength is well

recognized. The explanation is straight forward; longer fibers tend to distribute the stress over a greater area, over more fibers and more bonds, while short fibers allow the stress to be concentrated in a smaller area. Tearing Resistance: Tearing resistance/ strengths is the ability of the paper to withstand any tearing force when it is subjected to. It is measure in both MD & CD, expressed in mN (mili Newton).

  The procedural standards are explained in TAPPI T 414, ISO 1974 & SCAN P11

 

Typical Tear Resistance Values

Grade Elmendorf Tear mN

Coating Base (80g/m2) 500 - 700

Bond (100g/m2) 700

Office/Business Paper (80g/m2) 500 - 600

Test Liner (186g/m2) 1800

Tensile Strength   The tensile force required to produce a rupture in a strip of paperboard, measured in MD & CD, expressed in kN/m. Tensile strength is indicative of fiber strength, fiber bonding and fiber length. Tensile strength can be used as a potential indicator of resistance to web breaking during printing or converting. The procedural standards are explained in TAPPI T 494.

  Tensile Energy Absorption (TEA): TEA is the Tensile Energy Absorption, ie the amount of work required to break the sheet under tension.

Z Direction Tensile Strength: Or internal bond strength provides an indication of strength of board in relation to glue bonding at carton side seams and possible Delamination on scoring, or use of high tack coating. The procedural standards are explained in TAPPI T 541.

 

Typical Tensile Index Values

Grade MD (Nm/g) CD (Nm/g)

Newsprint (40 - 49g/m2) 45 -60 -

Stationery (50-100 g/m2) 40-70 20-40

Tracing Paper (60-110 g/m2) 70 40

Test Liner (186 g/m2) 175 80

Wet Strength  

Some grades of paper such as tea bag paper, coffee filter paper etc. come in contact with water in use. So these paper have to be strong enough to withstand tear, rupture or falling apart when saturated with water. To impart wet strength, paper are treated chemically.

 

Typical Wet Tensile Strength Values

Grade Dry Tensile Strength (g)Wet Tensile Strength (g)

Kitchen Towel  (20g/m2), 2 ply 650 200

Facial Tissue (13g/m2) 2 ply 115 35

Miscellaneous Properties

Ash Content   The residue left after complete combustion of paper at high temperature. It is generally expressed as percent of original test sample and represents filler content in the paper. As it is ash content is not important property of paper but in some grade of papers such as filter papers are ash free and other such as cigarette tissue have certain level of filler to control cigarette burning rate.

  The ash content measurement procedural standards are explained in TAPPI T 413, SCAN P5, ISO 1762.

 

Typical Ash Content Values

Grade %

Market Wood Pulp 0.3 - 0.5

Newsprint 0 - 12

LWC 30 - 50

Fine Paper 0 - 35

Dirt Content   The paper may have number of dirt specks or contraries. These specks can be any unwanted foreign particle that is visible to the eye such as bark, undigested wood (shives), pitch, rust, plastic, slime etc. For pulp, paper and board the number or area covered by such specks on both surfaces and sometimes in the body of the material, can be estimated in either reflected or transmitted light.

The number of specks of each area are expressed either as mm2/Kg for pulp or mm2/m2 for paper

 

Typical Dirt Content Values

Grade %

Bleached Market Wood Pulp < 7 mm2/Kg

Newsprint from deinked pulp 100-300 ppm

Fine Paper from deinked pulp < 10 ppm

  pH

The pH value of paper can show residual acidic/alkaline chemicals in pulp, or atmospheric pollutants (e.g. SO2) in valuable paper archives.  

The pH value of paper can be determined by:

- Disintegrating the paper in hot distilled water  and determining the pH of the extract.- Disintegrating the paper in cold distilled water  and determining the pH of the extract.- Directly using a wet electrode on the paper surface.

These 3 methods measure different solutions and so give different

Permanence   Permanence is degree to which paper resists deterioration over time. Permanent paper can resist large chemical and physical changes over and extended time (several hundred years). These paper are generally acid-free with alkaline reserve and a reasonably high initial strength. Paper containing pure cellulose fiber are more permanent. Permanency is desirable in currency, bond and record papers.

  Pin Holes

  Imperfections in paper which appear as minute holes upon looking through the sheet. They originate from foreign particles, which are pressed through the sheet. Absence of pin hole in electrical grade papers is very important.

  Porosity

  Because paper is composed of a randomly felted layer of fiber, it follows that the structure has a varying degree of porosity. Thus, the ability of fluids, both liquid

and gaseous, to penetrate the structure of paper becomes a property that is both highly significant to the use of paper. Paper is a highly porous material and contains as much as 70% air. Porosity is a highly critical factor in Printing Papers Laminating Paper, Filter Paper, Cigarette Paper. Bag Paper, Anti-tarnish Paper and Label Paper. Porosity is the measurement of the total connecting air voids, both vertical and horizontal, that exists in a sheet. Porosity of sheet is an indication of absorptivity or the ability of the sheets to accept ink or water. Porosity can also be a factor in a vacuum feeding operation on a printing press.

  Air Resistance (Gurely Method): It is the resistance to the passage of air, offered by the paper structure, when a pressure difference exist between two sides of paper. It is measured as the time for a given volume of air to flow through a specimen under specified conditions. Air resistance is indirect indicator of degree of beating, compaction of fibers and type and amount of fillers.   The Gurely Method is explained in TAPPI T 460 and TAPPI T 536 for low and high air resistance respectively.   Air Resistance ( Sheffield Method): is explained in TAPPI T 547  

Typical Porosity Values

Grade Gurley Air Resistance (sec) Bendtsen (mls/min)

Uncoated Paper   500-1500

Coated Paper   0-10

Test Liner (186 g/m2)   25

Gasket   1-5

Blotting Paper 1 -2  

  For more on Porosity, please visit http://www4.ncsu.edu/%7Ehubbe/TShoot/G_Poros.htm

Print Quality

The degree to which the appearance and other properties of a print approach a desired result. Lot of parameters in paper surface like roughness, gloss, ink absorption, whiteness, brightness affect this.

  Printability

  The extent to which properties of paper lends them to the true reproduction of the original artwork. This is influenced by the printing process and can be evaluated in terms of - dot reproduction, dot gain, print gloss, hue shift and print uniformity.

  Sizing / Cobb

 

Because paper is composed of a randomly felted layer of fiber, it's structure has a varying degree of porosity. Thus, the ability of fluids, both liquid and gaseous, to penetrate the structure of paper becomes a property that is both highly significant to the use of paper. The need to limit the spreading of ink resulted in "sizing" the paper with gelatinous vegetable materials which had the effect of sealing or filling the surface pores. Later, the term "sizing" was applied to the treatment of paper stock prior to the formation of the sheet, with water-repellent materials such as rosin or wax. Resistance towards the penetration of aqueous solution / water is measured by Sizing or Cobb values. The surface water absorption over 60 seconds, expressed in g/m2, measured by Cobb Test. The procedural Standards are explained in TAPPI T 441.

 

Typical Cobb Values

Grade g/m2

Bond 24-30

Office/Business Paper 22-26

Test Liner (186 g/m2) 100

Unsized 50+

Carbonless Base 18-22

Water Absorption (EDGE WICK)   Water absorption at the edge, expressed in kg/m2, using Wick Test. Board surface is sealed with waterproof tape on both sides, weighed, placed in water @ 80°F for 20 minutes and weighed again to measure the water absorbed by wicking. It is an important test for measuring the water absorption capacity of cupstock grade, which is used for the manufacture of soft drink cups.

Corrugated Boards - Bursting Strength   The combined tensile strength and stretch of a material as measured by the ability of the material to resist rupture when pressure is applied under specified conditions to one of its sides by an instrument used for testing the property. Testing for the bursting strength of paper is a very common procedure, although its value in determining the potential permanence or durability of paper is suspect.

Corrugated Boards - Ring Crushed Test    Ring Crush is a traditional test of linerboard and corrugating medium strength.  Ring crush measures compression resistance, and this compression strength is considered to relate to the eventual compression strength of combined board made from the component. Linerboard called high strength or high performance linerboard is board that is able to achieve a specified minimum ring crush at basis weights that are lower than traditional basis weights.

  Corrugated Boards - Concora Crush Test 

  The Concora Crush Tester performs a series of tests to determine the rigidity and crush resistance of corrugated material. It is used in conjunction with the Concora Liner Tester. The first test measures the flat crushing resistance of a laboratory-fluted corrugated material. The second test determines the edgewise strength, parallel to the flutes, of a short column of single-, double-, or triple-wall corrugated board. The third test evaluates the ability of corrugated material to contribute to the compression strength of a corrugated box by measuring the edgewise compression strength of a laboratory-fluted strip of corrugated material in a direction parallel to the fluted tips.

  Corrugated Boards - Flat Crush Strength 

  The flat crush test is a measure of the resistance of the flutes in corrugated board to a crushing force applied to the surface of the board under prescribed conditions. Flat crush is a measure of the flute rigidity of corrugated board. A high flat crush value indicates a combination of good flute formation and at least adequate strength medium. Low flat crush may indicate a number of conditions including low strength medium, leaning flutes and crushed flutes.

The three most important Parameters which defines the pulp are. 1.) Fiber Length, 2.) Brightness, 3.) Pulping process used. e.g. Northern Soft Wood Bleached Kraft (NSWBK). The Northern Soft Wood tells it is long fiber pulp. Bleached tells, it has high brightness and Kraft tells that Kraft (Sulfate) pulping process is used to produced this pulp. Similarly Southern Hard Woof Unbleached Kraft, will be a short fiber wood unbleached (low brightness) pulp made by kraft process. Link to a few typical Market Pulp data sheets

http://www.ariver.com/HardwoodDataSheet.pdf

http://www.ariver.com/HardwoodDataSheet.pdf

 

Ash Content in Pulp  Ash content in pulp may consists of various chemicals used during pulping/bleaching, mineral matter from wood or metallic matter from pipes and other machinery. It is not important parameter of pulp.   

  Ash is the residue left after igniting pulp at 525 0C (As per TAPPI T211). Ash is reported in % of residue to dry pulp basis.

  The standard procedure of measuring ash content is laid out in  TAPPI  T211, ISO 1762

Brightness of  Pulp Brightness of paper is discussed in Paper Properties. The paper brightness is mainly dictated by pulp brightness. There are some modification in stock preparation which can alter paper brightness to some extent such as filler, sizing, whitening agent, dying etc.  In short 

  Conductivity of Pulp

Electrical grade papers such as cable paper, condenser tissue or insulation paper etc., require very low conductivity to electricity. The presence of metal ion more specifically iron ion contribute to pulp conductivity The pulp used for electrical grades are washed with demineralized water, beater or refiner use lava or other non-metallic bars and contacting surfaces of all equipment are made of stainless steel.

Values for the conductivity of the water extract of the pulp are expressed in µS/m. 

         S = Siemen (SI unit of electric conductance) = 1 mho.

  Dirt in Pulp

Dirt content of pulp particularly of recycled pulp is important for its suitability to make fine paper. Dirt is any foreign material in pulp. TAPPI defines dirt as foreign matter in a sheet which, when examined by reflected, not transmitted light, has a marked contrasting color and has an equivalent black area of 0.04 mm2

or more.   

The standard procedure of measuring dirt content is laid out in  TAPPI  T213   Drainage Time of Pulp

Here the drainage time of pulp is discussed in reference to market pulp and/or unrefined pulp. The drainage time of pulp or freeness or slowness of pulp is modified to have some desired properties in the paper, here that is not discussed.   Drainage of unrefined pulp which is measured as freeness can give an indication on : 1) Fiber Length of pulp, as long fiber pulps have more freeness compared to short fiber pulps, 2) Damage to fiber during pulping, bleaching or drying as short fibers or fines produced during pulping operation, reduces pulp freeness, 3) Refining energy required to achieve certain slowness during stock preparation.  

  The standard procedure of measuring pulp drainage is laid out in  TAPPI  T221, T227, ISO 5267-1 and ISO 5267-2

  Dry Content of Pulp 

Consistency:  is the term used to describe solid content of  pulp during pulp processing. For pulp and paper maker this is the most important process parameters. All equipments are designed to handle pulp at and up to certain consistency. Pulp consistency is roughly divided in to three ranges:

  Low Consistency: <5% Medium Consistency: 5 - 15%  High Consistency: >15%

  It is the desire of every pulp maker to keep pulp at the highest possible consistency to minimize dilution water usage and which ends up as effluent. Higher consistency also helps in reducing the bleaching chemical consumption. But there are practical limitation of handling pulp at higher consistency such as high viscosity which make pulp flow very difficult.   

The standard procedure of measuring pulp consistency (up to 25%) is laid out in  TAPPI  T240.

  Moisture Content of Market Pulp:  is important from storage, transportation and handling point of view. Most of the market pulp are sold, stored, transported and used as air dry. The useable part of pulp is dry fiber only, so the tendency is to minimize the moisture content op pulp.

  Small quantity of pulp is sold as wet lap also. Wet lap pulp is not dried at source and transported at about 50% moisture content. It is feasible for short distance transportation and if pulp is to be used immediately at user end.

  Extractives (Low Molecular Weight Carbohydrates) in Pulp 

The low molecular carbohydrates indicates an extent of cellulose degradation during pulping and bleaching process, which may effect pulp strength and other properties. Pulp is treated with 1% hot NaOH solution for one hour to estimate loss of yield due to extractives.   

  The standard procedure of measuring 1% Hot Alkali Solubility is laid out in  TAPPI  T212

Fiber Length of Pulp Length of fibers  (arithmetic average, weighted average etc.) is one of the most important parameters of pulp. Pulp strength is directly proportional to fiber length and dictates its final use. A long fiber pulp is good to blend with short fiber pulp to optimize on fiber cost, strength and formation of paper. Softwood with pulps in general have longer fiber compared to hard wood pulp. Pulp made from woods grown in cold climate in general  have longer fiber compared to wood grown in warmer climates.     Chemical pulps in general have higher fiber length compared to semi chemical pulp and mechanical pulp, when made from same wood. More fibers get damaged/shorten by mechanical action than chemical action.

  There are several method to measure /report fiber length of pulp. The 'fiber length of pulp by projection' is described in  TAPPI  T232. The 'fiber length of pulp by classification' is described in  TAPPI  T233. "Fiber length of pulp and paper by automated optical analyzer using polarized light' is described in TAPPI T271.   The coarseness of  pulp fiber  is described in  TAPPI  T234. 

Kappa Number of Pulp Kappa number is determination of relative hardness, bleachability or degree of delignification of pulp. It is important parameter of unbleached pulp which is to be bleached. 

  The method to find kappa # of pulp  is described in  TAPPI  T236.

 

Pulping Process Though the pulping process used is directly not a pulp property but this is one of the most important parameters used in specifying the pulp. As we move  from full mechanical to full chemical pulping process, strength of pulp and bleachability improves. Strength improves due to less degradation of fibers and bleachability as more lignin is removed in chemical than mechanical pulping processes. 

  Yield: Pulp yield is mainly govern by the pulping process. Mechanical pulping processes which provide high yield, retain almost all constituents of wood. Lignin which is second highest to cellulose, does not bond to itself or cellulose fibers as fibers do, don't contribute to any bonding, resulting in weak pulp. Secondly lignin is brown in color and to maintain high yield of bleached pulp, lignin is not removed during bleaching, but only chemically modified. 

  Tensile Strength of Pulp

This is not the tensile strength of individual fiber, which is even higher than or comparable with steel. The tensile strength discussed here is maximum strength of randomly oriented pulp fiber when formed in a sheet. This tensile strength gives an indication of the maximum possible strength of pulp beaten under ideal condition. This again an indication of what level of tensile strength  can be achieved in real paper making environment.

  One way of measuring tensile strength of pulp is "zero span breaking strength' described in  TAPPI  T231. Wet zero span tensile strength of pulp is measured using TAPPI T273. 

Viscosity of Pulp Solution viscosity of a pulp gives an estimation of the average degree of polymerization of the cellulose fiber. So the viscosity indicate the relative degradation of cellulose fiber during pulping /bleaching process.   Dissolving pulps from wood, which contains a large proportion of  alpha cellulose, give higher viscosity values than paper pulps.    The standard procedure of measuring pulp viscosity is laid out in  TAPPI  T230