Process for dyeing fur skins with oxidation dyes

A process for mordanting fur skins which comprises the steps of:

• combining at least one metal salt and glyoxylic acid, to form a mordanting solution wherein the metal salt is an iron salt, a copper salt, a copper-iron salt, a chromium-copper salt, an iron-chrome alum salt, a copper-chrome alum salt, potassium dichromate, sodium dichromate, or mixtures thereof;
• bringing said fur skins into contact with said mordanting solution for a time sufficient to effect a mordanting pretreatment of the fur skins with the mordanting solution that contains glyoxylic acid and introducing the fur skins into a dyebath.