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Abstract
Storage of photographic film for long periods of time, particularly under adverse conditions, may lead to a loss in sensitivity and a gain in fog density. The effect of ageing photographic films in various atmospheres has been examined. Storage in oxygen causes a more rapid loss in sensitivity, but less fog formation, than storage in nitrogen. Deterioration of photographic properties during storage of film under reduced pressure appears due, at least in part, to removal of oxygen and moisture. It is concluded that the effect of environmental conditions on ageing is, in general, in agreement with the equation:
where Ag represents a sensitivity or fog centre on the surface of the silver halide grain.
It has been shown that ageing fog predominates at the surface of the silver halide grains. However, an internal fog is also produced, which is attributed to a thermal Herschel effect. The internal fog is not attacked by oxygen.
Notes
* Read to the International Conference on the Science and Applications of Photography, organized by the Royal Photographic Society . London. September 1953.