Condition of hides & skins during and after lockdown

By Kenan Özcan

Most tanneries currently have similar questions for their stock; how to work with longtime resting pickled and tanned hides/skins in the most suitable way?

Pickled skins would last longer due to the natural fat content. These only would require approximately 50% or more wetting back time and lower rpm drum speed in the beginning. Suppose a synthetic fatty auxiliary like Synthol EM 336 would be used during the de-pickling stage at 0,25-1%. In that case, the wetting back can be improved significantly, and a longer running time might be avoided. Synthol EM 336 fastens the wetting back process while dispersing the natural fat, preparing the skins for the next process steps. Depending on the skin’s condition, an anionic or non-ionic surfactant can be used along with Synthol EM 336.

On split or shaved tanned stock which stays well for a longer period of time, the wetting back can be improved by using 0,25-0,75% Synthol EM 336. Most wet-blue supplied by 3^rd tanneries might contain an active basifying agent, resulting in a buffer-effect at the cross-section during a longer storage time. In such a case, a small addition of Sodium bisulfite (0,25-0,5%) can help to reduce the buffer at the cross-section to allow alkali or acids to penetrate evenly. This can enhance the penetration of re-tanning agents, dyestuffs, and fatliquors while avoiding excess running times at later stages.

In the case the end article is Transport Leather related, a fogging optimized auxiliary Synthol PF 991 can be used for the same purposes on bovine material.

Read more about Synthol EM 336 and Synthol PF 991.