Phenolic plastic
The first fully synthetic plastic, and durable enough that its real cleaning risk is what somebody does to it rather than what it does to itself.
What not to do
Water is unsafe on Phenolic plastic
Unsafe
Do not do this. The risk is established, and it is described below.
Evidence
Supported
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)
In detail
Phenol-formaldehyde plastic — Bakelite being the best-known trade name — was the first wholly synthetic plastic and is still found in handles, radio and telephone cases, electrical fittings, cookware knobs and jewellery. Compared with the cellulose plastics it is a stable, robust material. It has two documented vulnerabilities worth knowing. Some phenol-based plastics contain WOOD FILLERS, and conservation guidance records those fillers as susceptible to pest attack — so an insect problem in a phenolic object is possible and is not a cleaning problem. And, like all plastics, it is damaged by inappropriate cleaning: solvent or water-based cleaning can cause stress crazing, swelling or distortion. The practical position is that a phenolic object usually survives ordinary handling well and is most often ruined by an attempt to restore its shine with a solvent or an abrasive.
Why
- Phenolic plastic is explained by Damage versus soiling
- Phenolic plastic is explained by Solvent crazing
The stable plastic. Its realistic failure is somebody trying to restore the shine with a solvent.
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 wood fillers in some phenol based plastics are susceptible to pest attack, and that inappropriate solvent or water based materials will cause stress crazing, swelling or distortion of plastic objects. (states this directly)
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)