Process for dyeing leather with dye mixtures

A process for dyeing leather, which comprises applying a dye mixture to the leather wherein the dye mixture comprises at least two dyes selected from the group consisting of

• a) a yellow dye of formula ##STR32## wherein R.sub.1 is C.sub.1 -C.sub.4 alkyl,
• R.sub.2 is OH or NH.sub.2,
• R.sub.3 is hydrogen or halogen,
• R.sub.4 is hydrogen or sulfo,
• R.sub.5 is hydrogen, halogen, sulfo or a group ##STR33## the phenyl rings of which last three mentioned groups may be substituted by halogen, and
• R.sub.6 is hydrogen, halogen or a group ##STR34## wherein R.sub.7 is hydrogen or C.sub.1 -C.sub.4 alkyl, R.sub.1 is C.sub.1 -C.sub.4 alkyl and n is 0, 1, 2 or 3,
• b) a red dye of formula ##STR35## wherein R.sub.8 is sulfo or ##STR36## R.sub.9 is sulfo, ##STR37## or a group ##STR38## wherein R.sub.7 is hydrogen or C.sub.1 -C.sub.4 alkyl, R.sub.1 is C.sub.1 -C.sub.4 alkyl and n is 1, 2 or 3,
• R.sub.10 is hydrogen, C.sub.1 -C.sub.4 alkylcarbonylamino or halo-C.sub.1 -C.sub.4 alkylcarbonylamino, and
• R.sub.11 is hydrogen or halogen, and
• c) a blue dye of formula ##STR39## wherein R.sub.12, R.sub.13 and R.sub.14 are each independently of one another hydrogen or C.sub.1 -C.sub.4 alkyl,
• R.sub.15 is hydrogen, methyl, --SO.sub.2 --NH--R.sub.17 or --CH.sub.2 --NH--CO--R.sub.18, and
• R.sub.16 is hydrogen, C.sub.1 -C.sub.4 alkyl or R.sub.15, and R.sub.17 is hydroxy-C.sub.1 -C.sub.4 alkyl and R.sub.18 is phenyl or halo-C.sub.1 -C.sub.4 alkyl.