This ppt presentation has 187 slides, some with notes. It is much more than my short presentation. It includes sections on identification, degradation,

this ppt presentation has 187 slides, some with notes. It is much more than my short presentation. It includes sections on identification, degradation, conservation and storage and

display. It is meant as an aide memoire as many of the slides are to support discussions.

Should you need any help or further explanation please email me on [email protected]

Please accept that this ppt presentation is my copyright.I am normally happy to visit collections which may include plastics materials and to give advice on identification and

associated guidance. Please understand that I do not have any organisation to fund these visits so I shall have to make a

charge for this service. Compared to the risks associated with degrading collections, this charge should be considered an

investment!Colin Williamson, Mansion House, Ford, Shrewsbury, SY5 9LZ

[email protected]

Plastics

Colin Williamson

materials

Plastics

Colin Williamson

materialsproduction techniques

Plastics

Colin Williamson

materialsproduction techniques

identification

Plastics

Colin Williamson

all you ever wanted to know about plastics


in 3 x 20 minutes


in 3 x 20 minutes+ questions +discussion

only 2 types of plastic

thermosetting

only 2 types of plastic

thermosettingthermoplastic

thermosets

moulded whilst soft and hot‘set’

demoulded hotonce heated and ‘cured’ won’t melt

againgenerally compression moulded

thermosets

Bois Durcirubber & vulcanite

phenol formaldehyde - Bakeliteurea formaldehyde - Bandalasta

GRP – glass fibre reinforced polyesterepoxies – adhesives

polyurethane

compression moulding - thermosets

Phenol formaldehyde – Bakelite

thermoset

thermoplastics

melted to form shape

cooled to set in mould

can be re-melted

thermoplastics

injection mouldfilm blow

bottle blowextrudecalendar

rotomouldcompression mould

combination

injection moulding thermoplastics

extrusion - thermoplastics

calendar – sheet

thermoformingthermoplastics sheet

thermoplastic materialscellulose esters – Celluloid, CApolyethylene - polythenepolypropylenepolystyrene – also expanded, HIPS & ABSpvc – flexible or rigidPMMA – acrylic (Perspex)- sheetpolycarbonatepolyamide – nylonetc., etc., etc.

Identification

Identification

educationthirst for knowledge

Identification

educationthirst for knowledge

conservation

Identification

non-destructivenon-invasive

Identification

appearance

dating - style & design

Identification

appearance

dating – trade marks, patents

British Patentsprior to 1916 – annually

1916 100,001 1950 634,001

1920 136,852 1955 721,191

1925 226,571 1960 826.321

1930 323,171 1965 978,901

1935 421,827 1970 1,175,851

1940 516,338 1975 1,378,941

1945 566,451 1980 2,023,381

1842 – 1867 1868 - 1883

A letter occupying the top of the diamond indicates the

year A 1845 J 1854 S 1849

B 1858 K 1857 T 1867

C 1844 L 1856 U 1848

D 1852 M 1859 V 1850

E 1855 N 1864 W 1865

F 1847 O 1862 X 1842

G 1863 P 1851 Y 1853

H 1843 Q 1866 Z 1860

I 1846 R 1861

If a number occupies the top of the diamond, the right field indicates the

year

A 1871 I 1872 U 1874

C 1870 J 1880 V 1876

D 1878 K 1883 X 1868

E 1881 L 1882 Y 1879

F 1873 P 1877

H 1869 S 1875

Bandalasta – urea/thiourea f

Xylonite – cellulose nitrate

Identification

appearance

colour and transparency

Transparent (i.e. glass clear) as thick solids (>2mm)

PMMA – acrylic, Perspex, Plexiglaspolystyrenepolycarbonatecast phenolic – normally tintedpolyestercellulose esterssilicones, polyurethane

transparent solids

polystyrene polycarbonate

Transparent (i.e. glass clear) as thin film or sheet

as solid +

PVC both rigid and flexiblepolypropyleneregenerated cellulose (Cellophane)polyethylenePET (polyethylene terephthalate)

Only opaque (at best, translucent)

phenol + urea formaldehyde – mouldedgutta perchavulcanite Bois Durci + most compositionsbitumen + cold moulded compositionscomposites, including GRPABSfoams

Colour

phenol formaldehyde – Bakelite – darkcast pf – shades of amberpigment or compoundwood or cloth fillers

phenol formaldehyde – Bakelite

dark colours

Cast phenol formaldehyde – amber shades

Cast phenol formaldehyde – amber shades

pf – colour in blotches

thiourea formaldehydecolour pigment particles

wood flour filled shellac

cloth filled pf

cloth filled pf - Tufnol

Identification

appearance

surface finish

knife marks in CN sheet

‘orange peel’ on urea formaldehyde

‘sink marks’ modern inj. mld

Identification

appearance

degradation

cellulose nitrate – acidic, wet

cellulose nitrate, acidic, wet

cellulose acetate, plasticiser, dry

CA – distortion due to shrinkage after plasticiser migration

CA, plasticiser migration, constrained shrinkage

Casein, moisture

Identification

appearance

function

Identification

appearance

production method

Thermoformed sheet

cellulose nitrate – very common pre 1950

casein – very limited bending

polystyrene – very common post 1950

uPVC – very common post 1950

PMMA – Perspex , common post 1950

many other modern materials can be post formed from sheet

Blow moulded

polyethylene – eg detergent bottlesPET – eg fizzy drink bottles

also uPVC, polypropylene, polycarbonate

Rotation Moulded

polyethylene, e.g. canoes, road conesplasticised pvc, e.g. footballs, dolls

also nylon and polycarbonate

Injection moulded

most thermoplastics

except casein and cellulose nitrate

thermosets after 1960

Compression moulded

almost all plastics materials but commercially not viable for modern thermoplastics.

typical of thermosets

Casting

polyester (especially embedding resins)

PMMA (especially embedding resins)cast Phenolicpolyurethane foam, e.g. shoes

‘old vulcanite plaque’

‘old vulcanite plaque’ - bubbles

‘old vulcanite plaque’ – reverse raised rim

‘old vulcanite plaque’ – reverse raised rim, crack, sawdust

‘old vulcanite plaque’ raised rim, crack, sawdust

modern polyester

extrusion

most thermoplastics

parallel marks along the long axis film and sheetrod and profile

fibres

Identification

physical properties

hardness

some plastics are softer than a finger nail

polyethylenepolypropylenegutta percha (except very old)plasticised pvcpolyurethanerubber

smell

phenol cast phenolicsulphur vulcanitecamphor cellulose nitratevinegar cellulose acetate

(degrading)waxy polyethylene

Identification physical properties

specific gravitysolventsheat & fumes odoursmelting pointanalytical methods e.g. FTIR

Identification - DatingPre 1840

Compositions wax, resins, shellac, gums, glue, drying oils

Papier Maché

Hoof and Horn

Tortoiseshell

Amber

1840 – 1880

More compositions, especially shellac based

Gutta percha

Bois Durci

Vulcanite

Identification - Dating1880 – 1900

Cellulose nitrate

Compositions decrease

1900 – 1920

Cellulose nitrate increases

Cellulose acetate

Casein

Bitumen

Identification - Dating1920 – 1939

Phenol formaldehyde (cast phenolic, Bakelite)

Thio-urea/urea formaldehyde

Cellulose acetate injection moulded

Melamine formaldehyde

(polystyrene, polyethylene, pvc, pmma etc. )

1945 – 1960

Thermosets decline

Semi-synthetics decline

Thermoplastics increase

Composites introduced

Foams, thermoplastic and thermosetting

why identify ?

why identify ?

to identify potential problems

why identify ?

to identify potential problemsto identify problem materials

problem materials

cellulose nitrate – Celluloidcellulose acetate

pvcpolyurethane foams

questions

questions

there’s no such thing as a stupid question

questions

there’s no such thing as a stupid question

only stupid answers

Degradation

surface bloomdistortionsplitting

colour changeembrittlement

crazing

Degradation



crazing

cellulose nitrate – acidic, wet

cellulose nitrate, acidic, wet

cellulose acetate, plasticiser, dry

Degradation



crazing

CA – distortion due to shrinkage after plasticiser migration

CA, plasticiser migration, constrained shrinkage

CA, plasticiser migration, constraine

d shrinkage

Degradation



crazing

Horn brooch front

Horn brooch back

CN billiard ball, zinc oxide

CA negative film

CN delamination

Degradation



crazing

CA, UV colour fade

CN, iron stain

CN

Polypropylene, UV, phototenderised

Rubber, oxygen +

UV

Vulcanite, UV + water

Vulcanite, UV + water

Vulcanite, UV + moisture

pf (Bakelite) UV

pf (Bakelite) UV on pigment

Degradation



crazing

cn – stage 1

cn – stage 2

cn – stage 2

cn – stage 2

cn stage 3

cn movie film – stage 1

gutta percha sheet, oxygen

Irradiated polyethylene

uPVC, UV

Degradation



crazing

Casein, moisture

Casein, moisture

Degradation



crazingweeping

Degradation

Weeping – typically CA plasticiser loss

Stability of Plastics

Cellulose Nitrate(Celluloid)

hydrolysis Nitrogen oxides off gas

Nitrous and nitric acids

Cellulose Nitrate(Celluloid)

off gassing - corrosionmoist haze

acidic surfacecuboid cracking

movie film dry deepfreeze

Cellulose Acetate

hydrolysis acetic acid - vinegar plasticiser migration

Cellulose Acetatesmell of vinegar

weepingdry plasticiser on surface

distortionblisters

PVCoriginally unstable but UV and ΔH stabilisers added

plasticiser migrationrigid – darkens & embrittlesflexible – stiffens/liquefies

Polyurethanes

unstable as foam as high surface area and O2

exposuredarken, powder, crumbling

Other polymers

all UV sensitive transparent worse than

opaque

amorphous (e.g. PMMA, P’s, Polycarb) – solvent

sensitivity

Caring

basic considerationsstorage inc. passive cons.

cleaninghandling

degradation indicatorsdisplay

Caring


cleaninghandling


Basic considerations

identify the material before acquisition


identify the material before acquisitiononly acquire non-degrading items



physical damage better than chemical



physical damage better than chemicalexposure stress, labels, paint, adhesive

Caring


cleaninghandling


storage

no sunlight, heat, & damp

no lights in stores30-50% RH

<5o C < 30% slows degradation

storage

no sunlight, heat, & damp no enclosed wrappings

allow off gassing

except for passive conservation

storage


acid free tissue

storage


acid free tissuenot touching other items

storage

not touching other items

plasticiser migrationdegradation bi-products

colour bleed

storage



supported

storagesupported

stresssculpted bed

cushionstrongest pointsopen frameworkcheck materials

(cf display)

storage



supportedindicators

storage

indicators

cresol papercresol string

storage



supportedindicators

passive conservation

storagepassive conservation

scavengersactivated charcoal – poss CN CAZeolites – ok CA film long termAgeless – ok for rubber NOT CN

CA

storage



supportedindicators

passive conservationgloves

storagegloves

lint free - snagging

non-absorbent (acids)

Caring


cleaning

Caring

cleaning

advisable for conservation but curatorial ?

Caringcleaning

water (sparingly) generally safe BUT

water generally safe BUT

not immersion? surface dyed casein

not vulcanitenot foam

not degrading CN

Caring

cleaning

olive oil ok for sticky labelsBUT

beware ESC

Caring

cleaning

wax polish ?

Caring


cleaninghandling


Caringdisplay

50 lux max30-50% RH

constant 200 C

clean(ed) airacid fumes, organic vapours

Caringdisplay

suitable plastics for direct contact

polyolefines (check stability and creep)polyethylene foam

PET – polyester eg, Melinex, Mylarnylons

Caringdisplay

un-suitable plastics for display/support

cellulose esters e.g.celluloidplasticised PVC

polyurethane foampaint – esp solvent

So, you’ve got plastics in the collection ???

So, you’ve got plastics in the collection ???

What to do

Survey

identify materials

Survey

identify materials

identify degradation

Survey

identify materials

identify degradation

determine risk

Category A – High Risk

Degradation startedLikely to affect other materials


Degradation startedLikely to affect other materials

Cellulose Nitrate – ‘celluloid disease’Attacked metals, wrapping


Actively degrading –record and discard -active conservation

-isolate

No active degradation –storage -6 monthly inspection -indicators-active conservation-cleaning

Category B – Medium Risk

Likely to degrade but products of degradation inoffensive

Polyurethane Foam

Store in reduced O2 environment

Agelessno light

PVC

Unplasticised – UV sensitive

Plasticised (flexible)Plasticiser loss -embrittlement

Eventually liquifies

Documents

This ppt presentation has 187 slides, some with notes. It is much more than my short presentation. It includes sections on identification, degradation,