Can anyone give me some expedient advice on the breakdown of synthetic rubber? I am working with Museum Studies students on a Hat show, and one item featured is a 1950s moulded synthetic rubber bathing cap. This cap was originally bright yellow with moulded sunflowers, but over time has begun to show mottled brown areas which have hardened, and begun to split. This appears to be an oxidisation process. The question I have is exactly what chemical process is occurring here? What compounds are reacting with oxgen, innate in the rubber? Any suggestions would be gratefully received, as the students' show opens tommorrow night, and the conservation label gets written this afternoon! Roxanne Fea Curator of Social History The Science Centre & Manawatu Museum, Palmerston North, New Zealand