Photographic Fogging

the formation of metallic silver or pigments during the development of unexposed black-and-white or multilayered color photographic materials. This harmful effect, which becomes more pronounced with an increase in the development time, reduces the quality of the photographic reproduction of tones and colors of the object pictured, increases the graininess of the photographic image, and decreases the accuracy of measurement of radiation power by the photographic method (photographic photometry). As a rule, the greater the light sensitivity of the photographic material, the higher the degree of susceptibility to fogging. To avoid fogging of the finished material, certain chemicals (potassium bromide, benzotriazole) that increase the selectivity of the photographic development are added to the developer. Fogging is rated by the optical density of blackening, or by the surface concentration of pigment in color developing, on the unexposed portion of the developed film layer.