celluloids

Celluloids are a class of early plastics derived from nitrocellulose. The material is formed by dissolving nitrocellulose in solvents with a plasticizer, such as camphor, to produce a transparent, moldable substance commonly known as celluloid. The name can be misleading, since the material is not pure cellulose.

Developed in the 19th century, nitrocellulose-based plastics were marketed as substitutes for natural materials like tortoiseshell, ivory, and gutta-percha. John Wesley Hyatt patented the process, and commercial celluloid found widespread use in film stock for motion pictures and photography, as well as in a variety of consumer goods including combs, buttons, eyeglass frames, jewelry, and knife handles.

Celluloids are thermoplastic and can be shaped when softened; they are transparent and can be colored. However, they are highly flammable and can pose hazards as they age. Aging can cause embrittlement or the migration of plasticizers, leaving sticky residues in some items. The nitrocellulose base also makes film stock prone to deterioration and poses fire risks, especially in older, unprotected formats.

Decline and legacy: By the mid-20th century, nitrocellulose-based film was increasingly replaced by cellulose acetate film, which offered lower flammability and improved stability. Today, celluloids are primarily of historical interest; the term continues to apply to early plastic materials and to certain specialty uses, though modern polymers have largely supplanted their broad range of applications.