Scientific American (magazine, April 2016, page 72) article deals with how a variety of plastics age and change composition in the process, sometimes resulting in unexpected challenges for conservators and the objects they're trying to preserve. Artifacts from NASA's early
history are self-destructing due to their peculiar compositions.
Might be helpful to folks who wish to learn what kinds of materials to keep away from
ancient coins even in display cases or storage boxes. We know about avoiding
PVC 'flips' for long-term storage but there are other plastics (e.g. old photographic film) that decompose into various acids and potentially corrosive substances.
PtolemAE
