The Mechanism of the Photographic Pressure Effect and its Relation to Latent Image Formation

Abstract

. Experiments revealed that desensitization of the total internal image at high intensity exposures has its origin in the fact that part of this total image behaves with respect to the pressure effect as a surface image. The deep internal image nevertheless always shows a sensitization by pressure. The appearance of a surface sensitization by pressure at very low intensities suggests that by pressure new electron traps are formed not only in the interior but also at the surface of the silver halide grains. The drop of surface desensitization by incubation of the pressed layer is explained as a recovery effect of the silver halide grains, whereas the increase of surface desensitization by incubation before pressure is ascribed to a softening of the silver halide crystals by a process analogous to that of annealing.