CN

CN is the abbreviation for celluloid, a group of thermoplastic plastics that are produced from cellulose nitrate and camphor as a plasticiser. Although highly flammable, celluloid was used in various products due to the lack of alternatives.

Originally intended for gears, it found use in combs, knife handles, ballpoint pens, spectacle frames and toys. Only with the introduction of polyethylene terephthalate (PET) was a safer alternative found. Until the 1950s, celluloid served as a carrier material for cinema films before it was replaced by safety films.