The film materials will be treated with care and may be used as a future preservation source, but there are no active preservation efforts. Preservation is a more active intervention and refers to the process of gathering the best surviving moving image materials and transferring them to the most stable format possible. Restoration refers to the costly and time-consuming activity of trying to bring a film as close as possible to its initial release form. This requires finding missing footage, replacing altered material, and repairing any physical damage done to the material. The goal of a restoration project is to be able to exhibit the restored film.
Nitrate stock decomposes over time and is highly flammable.
The great majority of films made before 1950 used nitrate-based film. The nitrate film has a high silver content and rich tones, providing a superior black and white image. In preservation programs, nitrate-based films are copied onto acetate stock. Even after the copies are made, both the acetate and nitrate copies are kept in the archives, but in separate areas. Acetate-based films are also known as safety film because they are not highly flammable and do not decompose like nitrate.