Process for hardening silver halide containing photographic layers with sulpho- or sulphoalkyl-substituted carbamoyl pyridinium compounds

A process for providing a photographic material comprising at least one silver halide emulsion associated with at least one supported layer containing protein in which the protein-containing layer is contacted with an effective amount of a hardener to harden the layer

• wherein the improvement comprises the hardener is carbamoylpyridinium compound of the formula ##STR13## in which R.sub.1 and R.sub.2 which are the same or different represent an alkyl group containing 1 to 3 carbon atoms, an aryl group which is unsubstituted or substituted which C.sub.1 to C.sub.2 alkyl or with halogen;
• or an aralkyl group which is unsubstituted or substituted with C.sub.1 to C.sub.2 alkyl or with halogen;
• or
• R.sub.1 and R.sub.2 together represent the groups required to complete a piperidine or morpholine ring which is substituted with C.sub.1 to C.sub.2 alkyl or with halogen,
• R.sub.3 represents hydrogen, methyl or ethyl,
• R.sub.4 represents ethylene or a single chemical bond,
• Me.sup.+ represents an alkali metal cation and
• X.sup.- represents Cl or Br.sup.-.