Desensitization by Spectral Sensitizers

Abstract

AbstractIt is well known that high concentrations of spectral sensitizers cause an overall desensitization. The degree of desensitizing action and the percentage of surface coverage, for which a sudden decrease in gamma and sensitivity takes place, are dependent on the structure of the spectral sensitizing dye, on the type of emulsion, on the pAg and on the kind of development.In the discussions about the mechanism of this desensitizing action, the retarding of development caused by the spectral sensitizers as mentioned already by James and Vanselow is often overlooked.In order to get an appreciation of the importance of this factor, the silver halide emulsions were exposed (to blue light) in liquid state. In this way it was possible to compare the action of the dye added before exposure with the dye added after exposure. For some emulsions, desensitization can be attributed to a large extent to a retarding of development, although certain desensitization also occurs during exposure.