Cellulose acetate film

[1] The chemical instability of cellulose acetate material, unrecognized at the time of its introduction, has since become a major problem for film archives and collections.

Cellulose diacetate film was first created by the German chemists Arthur Eichengrün and Theodore Becker, who patented it under the name Cellit, from a process they devised in 1901 for the direct acetylation of cellulose at a low temperature to prevent its degradation, which permitted the degree of acetylation to be controlled, thereby avoiding total conversion to its triacetate.

A cellulose diacetate film more readily dissolved in acetone was developed by the American chemist George Miles in 1904.

Miles's process (partially hydrolysing the polymer) was employed commercially for photographic film in 1909 by Eastman Kodak and the Pathé Frères.

In 1910, a newly discovered, non-inflammable, film format 'BOROID' was presented to the British cinematographic trade using acetate-based cellulose.

The Boroid company commenced trading on 21 November 1910, being originally registered in London at 58 Coleman St., moving to 104 High Holborn in May 1911, and finally to 48 Rupert St. in June 1913.

[3] Beginning in the 1980s, there was a great deal of focus upon film stability following frequent reports of cellulose triacetate degradation.

[6][7] A testing product developed by the Image Permanence Institute, A-D, or "acid-detection" indicator strips change color from blue through shades of green to yellow with increasing exposure to acid.

[9] While there has been significant research regarding various methods of slowing degradation, such as storage in molecular sieves, temperature and moisture are the two key factors affecting the rate of deterioration.

According to the Image Permanence Institute, fresh acetate film stored at a temperature of 21 °C (70 °F) and 40% relative humidity will last approximately 50 years before the onset of vinegar syndrome.

Enclosures that are breathable or that contain an acid absorbent are instrumental in reducing the rate of decay due to vinegar syndrome.

Sealed metal containers can trap the decay products released by the film, promoting the spread of vinegar syndrome.

Current standards now allow for scanning at more than ample resolution to produce a copy of the same picture and sound quality as the original.

)[citation needed] Cellulose acetate film is also used to make replicates of materials and biological samples for microscopy.