Tanning process of hides.

摘要

The invention relates to a process for tanning acidified wet raw hides. This process consists (a) in preparing a water-insoluble organic liquid bath, (b) in suspending in this bath an inorganic tanning agent based on a metal compound, especially a chromium salt or complex, (c) in adjusting the degree of hydration of the hides above a minimum threshold of 200% (weight of water added to the dry weight of hides) and below a maximum threshold corresponding to the limit of retention of water in the hide, (d) in bringing the hides thus hydrated into contact in the organic bath containing the tanning agent for a period of at least 4 hours and in slowly introducing a base into the bath so as gradually to raise the pH of the water retained in the hides to a final value of between a minimum threshold of 3.9 in the case of a chrome tanning agent, and a maximum threshold of 4.4 in the case of this chrome agent, and (e) in removing the hides from the bath and leaving them to rest for at least 24 hours. The process of the invention makes it possible to obtain at the same time a complete exhaustion of the tanning bath, an absence of release of tanning agent in the subsequent finishing operations and a leather of good quality.