Celluloid is the first commercially successful synthetic plastic material, developed in the 1860s and 1870s. It offered manufacturers a combination of flexibility, strength, and low-cost production. Celluloid revolutionized manufacturing processes and provided practical alternatives to expensive natural resources. Its introduction launched the modern plastics industry, leading to an expansion in consumer goods and new technologies.
The Chemistry Behind Celluloid
Celluloid is a mixture of two main components: nitrocellulose and camphor. Nitrocellulose, or cellulose nitrate, is created by treating natural cellulose fibers, often from cotton or wood pulp, with nitric and sulfuric acids. This process introduces nitrate groups onto the cellulose chain, creating a material similar to guncotton, which is a highly flammable explosive.
To transform this unstable material into a workable plastic, camphor is introduced as a plasticizer. Camphor, a waxy substance, is dissolved in alcohol and mixed with the nitrocellulose. This process changes the molecular structure into a homogeneous, dough-like gel that can be kneaded and pressed. The resulting mass is then formed into solid blocks or sheets under high pressure and heat.
Defining Characteristics and Risks
Celluloid was celebrated for its ability to be molded, sliced, and polished, making it a thermoplastic that could be reshaped with heat. It could be dyed in many colors and manufactured to imitate luxury materials like ivory, tortoiseshell, and horn. It possesses transparency and toughness, properties unmatched by earlier materials.
Despite these characteristics, celluloid is inherently unstable and presents hazards. Its primary drawback is extreme flammability due to its nitrocellulose base. Degraded celluloid film can spontaneously self-ignite at temperatures as low as 125°F (50°C). Once burning, it is nearly impossible to extinguish because it produces its own oxygen.
Over time, celluloid objects suffer from chemical decomposition. The camphor plasticizer can gradually sublime or “squeeze out,” causing the plastic to become brittle and prone to cracking. The breakdown of the nitrocellulose releases nitrogen oxide gases. These gases combine with moisture to form corrosive nitric acid, which accelerates decay and can destroy nearby materials, posing a serious issue for historical archives.
Celluloid’s Legacy in Early Industry
Celluloid’s initial commercial success was tied to the search for an ivory substitute, driven by the popularity of billiards. A prize offered in the 1860s for a replacement for ivory billiard balls spurred the material’s development by John Wesley Hyatt and his brother Isaiah. Although early celluloid billiard balls were occasionally reported to explode, the material quickly found broader use.
The most significant application of celluloid was in photography and motion pictures. Its ability to be manufactured into a flexible, transparent, and durable film base made continuous film rolls possible, paving the way for modern cinema. Celluloid film was the standard for theatrical 35mm productions from the late 1880s until the widespread adoption of acetate safety film in the 1950s. Beyond film, celluloid was used for consumer items, including doll heads, fountain pen bodies, and detachable collars. The material’s fire risk and instability ultimately led to its replacement by safer synthetic polymers.