Abstract: A restraining layer capable of retarding the diffusion of hydroxyl groups is of particular use in a neutralization system for the dye diffusion transfer process. The restraining layer of the invention comprises a film-forming linear polymer consisting of alternating hydrophilic and hydrophobic segments joined to one another by carbonate, urethane and/or ester groups. The neutralization system provides retarded reduction of pH in the photographic material.

Abstract: A neutralization system for the dye diffusion transfer process comprises an acid polymer layer containing a polymer with free acid groups and a retarding layer. The retarding layer contains a hydratable polymer which in its non-hydrated state is a barrier for hydroxyl ions and in its hydrated state provides no resistance for diffusing hydroxyl ions. The retarding layer is arranged between a laminate consisting of a light-sensitive film unit comprising at least a light-sensitive silver halide emulsion layer and a non-diffusible dye giving compound associated with the light-sensitive silver halide emulsion layer. The retarding layer allows a first high pH value to be maintained during a first time interval which is sufficient and necessary for producing the desired image density in the image receiving layer and thereafter a second low pH value to be adjusted within a second time interval which is less than half as long as the first.