Process for the trichromatic dyeing of leather

A process for the trichromatic dyeing of leather, comprising the step of contacting the leather with an aqueous dyebath which contains a red and a yellow dye, each of formula I ##STR18## wherein the substituents Z are each independently of the other nitrogen or a CH group,

• A and C are each independently of the other a radical of the benzene or naphthalene series, which radical carries a hydroxyl or carboxyl group in the o-position to the azo or azomethine group,
• B and D are each independently of the other the radical of a coupling component if Z is nitrogen, which coupling component carries the group X in the o- or alpha-position to the azo group, or are each independently of the other the radical of an o-hydroxyaldehyde if Z is the CH group,
• the substituents X are each independently of the other oxygen or a group of the formula --NR--, in which R is hydrogen or a C.sub.1 -C.sub.4 alkyl group,
• Me is chromium or cobalt,
• Y is the SO.sub.3 H, COOH or PO.sub.3 H.sub.2 group,
• p is 1 or 2 and
• n is an integer from 1 to 6,
• and a grey dye of formula II ##STR19## wherein R.sup.1 and R.sup.3 are each independently of the other and at least one is sulfo,
• A.sup.1 and A.sup.2 are each independently of the other the radical of 1-hydroxynaphthalene or 2-hydroxynaphthalene,
• R.sup.2 and R.sup.4 are ech independently of the other hydrogen or a group of the formula --CO--(O).sub.m --E, in which E is C.sub.1 -C.sub.5 alkyl and m is 0 or 1, and
• Ka.sup..sym. is a cation.