Casein plastic
A plastic made from milk protein. It is the only material in this catalogue that pests eat because it is food.
What not to do
Water is unsafe on Casein plastic
Unsafe
Do not do this. The risk is established, and it is described below.
Why we say this
Supported
Stated as a flat prohibition in the leaflet's do-not column, for plastics generally.
Sources
Conserve O Gram 8/4: Care and Identification of Objects Made from Plastic
National Park Service, US Department of the Interior · Government or regulator
Relied on for: That solvents and water must not be used to clean plastic, and that if in-depth cleaning is needed a conservator should be consulted. (states this directly)
Verification: a person has read the passage relied on.
Read on — The sections headed Plastics Identification, Causes of Deterioration and Signs of Deterioration, plus the ventilation guidance. Supports the claim as stated. Gives the household-plastics record a deterioration mechanism and explains the sticky-remote-control problem, which the catalogue previously had no account of at all. Also establishes that improper cleaning is itself a named cause.
Last reviewed by a person on .
In detail
Casein plastic is a protein-based material derived from milk, used from the early twentieth century for buttons, buckles, knitting needles, pen barrels and jewellery. It is included here for a property no other plastic has. Because it is protein, it is edible. Conservation guidance warns directly that casein plastic may attract parasites, and lists it alongside the wood fillers in some phenol-based plastics as susceptible to pest attack. A button collection or a set of vintage buttons showing small holes or surface grazing has a diagnosis that no cleaning product addresses. It is also water-sensitive in a way most plastics are not, being a protein rather than a hydrocarbon polymer. The general plastics rule applies with more force: dry methods only, no solvents, no water, cool and stable storage, and inspection every six months for the pest damage the material specifically invites.
Why
- Casein plastic is explained by Damage versus soiling
Related
- Casein plastic is commonly affected by Frass and pest residue
Sources for this page
Sources
Conserve O Gram 8/4: Care and Identification of Objects Made from Plastic
National Park Service, US Department of the Interior · Government or regulator
Relied on for: That casein plastic is a protein based material derived from milk which may attract parasites, that wood fillers in some phenol based plastics are susceptible to pest attack, and that objects should be monitored every 6 months with deteriorating objects removed. (states this directly)
Verification: a person has read the passage relied on.
Read on — The sections headed Plastics Identification, Causes of Deterioration and Signs of Deterioration, plus the ventilation guidance. Supports the claim as stated. Gives the household-plastics record a deterioration mechanism and explains the sticky-remote-control problem, which the catalogue previously had no account of at all. Also establishes that improper cleaning is itself a named cause.
Conserve O Gram 8/4: Care and Identification of Objects Made from Plastic
National Park Service, US Department of the Interior · Government or regulator
Relied on for: That plastics are subject to ageing and degradation, that the first visible signs are weeping, tackiness, discoloration, distortion, warping, crazing and embrittlement, that once present deterioration is rapid and irreversible, and that solvents and water must not be used to clean plastic. (states this directly)
Verification: a person has read the passage relied on.
Read on — The sections headed Plastics Identification, Causes of Deterioration and Signs of Deterioration, plus the ventilation guidance. Supports the claim as stated. Gives the household-plastics record a deterioration mechanism and explains the sticky-remote-control problem, which the catalogue previously had no account of at all. Also establishes that improper cleaning is itself a named cause.
Last reviewed by a person on .