Method for producing a leather semi-finished product

A process for the production of a semifinished leather product from an animal hide comprising:

• pretanning an animal hide with a chromium-free tanning agent to produce a pretanned animal hide,
• wherein pretanning is effected with the additional use of a clay mineral which, after stirring for 30 minutes in water at 50° C. at a circumferential rotor speed of from 5 to 25 m/s, has a number average particle diameter of less than 2 μm or a bimodal size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 μm and a second, coarser fraction whose number average particle diameter is less than 5 μm, in each case determined by the method according to ISO 13320-1, by combined laser light diffraction and light scattering, the proportion of the first, finely divided fraction being from 10 to 90% by weight, and
• wherein the pretanned animal hide is dried to a water content of from 5 to 45%, based on the total weight of the semifinished leather product.