Film consists of a plastic strip coated with an emulsion on which the actual images are found. The development of long filmstrips that combined flexibility, transparency and resistance were essential for the invention of cinema at the end of the 19th century. In 1889, film stock made of cellulose nitrate was finally perfected, paving the way for the unlimited possibilities cinema offered. Nitrate film was used for 35mm negatives and prints up until 1950.
Although strong and resistant, nitrate film still had a serious flaw: extreme flammability. Even when immersed in water, nitrate film can burn uncontrollably and release highly toxic fumes. The heat from a projector bulb could easily ignite a broken piece of nitrate film lodged in the projector. These accidents led to many fires and a number of deaths during cinema’s early years. Some solutions included fireproofing projection booths and designing projectors that enclosed nitrate film inside a secure compartment.
However, audiences and the authorities continued to worry, sometimes leading to panic as dangerous as the fire itself. Another unfortunate property of nitrate film is that it decomposes quickly, within a few decades of production. The process of decomposition cannot be halted once it starts. The vast majority of films made during the silent era were either lost or destroyed because of nitrate film’s flammability and rapid decomposition.