Process for making a pressure fog-resistant photographic element

Abstract

A method for controlling pressure-induced fog in a silver bromide photographic material involves surface treatment of the emulsion AgBr grains with thiocyanate and an iodide salt. In particular, a process for making a pressure fog-resistant photographic emulsion includes steps of forming a photographic emulsion containing cubic or cubooctahedral silver bromide grains, surface-treating the AgBr grains with a thiocyanate by adding the thiocyanate to the emulsion, chemically sensitizing the emulsion, maintaining the emulsion at a temperature and for a time sufficient to allow the thiocyanate to react with the grain surfaces, and then surface-treating the AgBr grains with an iodide salt by adding the salt to the emulsion in an amount and under conditions effective to fill in cubic faces of the AgBr grains. The latter step partially or fully converts the AgBr grains to octahedral grains. A photographic element can then be made by coating the emulsion on a suitable base.

Dependencies are inferred from the claim text.