Process for improving the light-fastness of leather dyeings

Process for improving the light-fastness of leather dyed with an anionic cobalt or chrome complex dye, which process comprises treating the leather before, during or after dyeing with a composition consisting essentially of a light-fastness improving amount of a compound of copper selected from the group consisting of (1) a copper salt of an inorganic or organic acid, (2) a copper salt of an inorganic or organic acid in admixture with a further organic carboxylic acid, (3) an acylhydrazone copper complex of the formula ##STR22## wherein R.sub.1 and R.sub.2 are each, independent of the other, hydrogen or an unsubstituted or substituted alkyl or aryl radical, Me is copper, Q is oxygen or NH and n is zero or 1, (4) a copper complex of the formula ##STR23## wherein R.sub.1 and Me are as defined above, and X is oxygen or sulfur, and (5) a copper complex of a compound of the formula ##STR24## wherein R.sub.3 is hydrogen, OH, alkyl or cycloalkyl, and wherein the ring A is unsubstituted or is further substituted by sulfo or sulfonamido.