Abstract: The present invention relates to a process for crosslinking hydrophilic colloids, preferably gelatine and most preferably gelatine present in a photographic material. A 1,3,5-triazine compound containing an NC--N.sup.- -- substituent bound to the triazine ring is incorporated into the hydrophilic colloid as a crosslinking agent.

Abstract: Compounds of the formula ##STR1## in which R.sub.1 signifies a group of the formula --NH.sub.2, --NH--R.sub.4 or --O--R.sub.4, in which R.sub.4 signifies a (C.sub.1-8)alkyl radical, a (C.sub.5-8)cycloalkyl radical or an unsubstituted or substituted phenyl, naphthyl or heterocyclic radical,Each of R.sub.2 and R.sub.3, which may be the same or different, signifies a hydrogen atom, a hydroxyl, (C.sub.1-8)alkoxy, amino, (C.sub.5-8)cycloalkylamino, (C.sub.1-8)alkylamino, (C.sub.1:8)dialkylamino, phenyl- or naphthylamino or N-phenyl-N-(C.sub.1-8)alkylamino group,A signifies a nitrogen atom or a group of the formula ##STR2## in which R.sub.6 signifies a hydrogen or halogen atom or a (C.sub.1-8)alkyl radical,Either n is 1 and D signifies the radical of a diazo component,Or n is 2 and D signifies the radical of a tetrazo component,Are useful as coloring materials, especially as pigments for plastics, synthetic resins, varnishes, viscose, cellulose acetate, printing inks and paper stock.