Process of hardening a silver halide photographic material with a 1-carbamoyloxypyridinium salt

A process for providing a hardened layer in a photographic material containing a light sensitive silver halide emulsion layer and at least one layer containing a binder selected from the group consisting of gelatin and homopolymers and copolymers which contain carboxyl groups coated on a support wherein the improvement comprises applying to the binder-containing layer a hardening amount of a 1-carbamoyloxypyridinium salt of the formula ##STR82## in which R.sub.1 represents a lower alkyl or aryl group,

• R.sub.2 represents a lower alkyl group or a group ##STR83## in which R.sub.6 represents hydrogen, or a lower alkyl or aryl group,
• R.sub.7 represents a lower alkyl group and
• R.sub.8 represents a lower alkyl group;
• or
• R.sub.1 and R.sub.2 together represent the atoms required to complete a heterocyclic ring selected from the group consisting of pyrrolidine, morpholine-, piperidine-, perhydroazepine-, 1,2,3,4-tetrahydroquinoline- or imidazolidine-2-one ring, or
• R.sub.1 and R.sub.2 together represent the atoms required to complete a piperazine ring in which the nitrogen that completes said piperazine ring is a member of the carbamoyl group of a second carbamoyloxypyridinium group,
• R.sub.3 represents hydrogen or halogen, or a lower alkyl, lower oxyalkyl, cyano, CONH.sub.2 or ##STR84## R.sub.4 represents hydrogen or a lower alkyl group, R.sub.5 represents hydrogen or a lower alkyl group and represents an anion.