Cellulose diacetate

This was the first safety film used by Eastman Kodak for 35mm in 1909, although not extensively available. In 1923 Kodak used it for the first 16mm and many other manufacturers used it for narrow gauges. In the 1930s quite a number of special 35mm films were coated on diacetate, notably Dufay film stocks.

Cellulose diacetate is still inflammable, although by comparison with nitrate is always said to be non-inflammable.

Cellulose diacetate does not last well. Vinegar syndrome film is more sever than with triacetate and the early stocks lost plasticiser and shrink very easily resulting in extremely curled, twisted, shrunken, brittle fragments. Even the best storage conditions are said not to save diacetate base from destruction. However, although the base suffers in time seriously, provided the film is in one piece, the chemical deshrinking processes, using acetone atmospheres, quickly returns the film, temporarily, to a flexible, even supple support which can be printed. Usually the film quickly shrinks back to its old state.