A process for the production of leather, wherein tanned animal hides are treated in step (A) with an aqueous liquor which comprises (a) at least one copolymer obtainable by copolymerization of (a1) at least one ethylenically unsaturated C4-C8-dicarboxylic acid or at least one derivative of an ethylenically unsaturated C4-C8-dicarboxylic acid and (a2) at least one C8-C100-α-olefin and, if appropriate, hydrolysis and/or at least partial neutralization, (b) at least one paraffin which is liquid at room temperature, (c) at least one synthetic nonionic emulsifier, the aqueous liquor being free of silicones, and furthermore silicone-free aqueous formulations and their use.