Photographic image is composed of a carrier, usually cellulose acetate and an image. The image of a black and white film will be converted into metallic silver during development. When color material developed, the image is formed by three organic color layers: cyan, magenta and yellow which are layered as a sandwich on the carrier. Both carrier and image are susceptible to deterioration. This is stronger for color, especially where organic materials are susceptible to a slow chemical reaction.
The degradation of organic material starts soon after the development of the film. This is why there is a disclaimer on the film packaging for the decline of the color. This problem was from 1950 to mid-1980 reinforced by the many development laboratories who were not familiar with this problem and developed with inappropriate material.
Deterioration of photographic material can be recognized first in parts with the least coverage: the high light areas for slides and the outer layer or the most unstable layer color layer. The photo or slide shows green or purple, degrading in a stronger color cast that continues until the image completely disappears
This discoloration occurs in color positives (slides), color negatives and printed photos.