Chrome Uptake and Thermal Stability of Wet Blue Leather Tanned by Static and Rotating Drum

Leather tanning can be done by soaking the skin in pits or rotating in tannery drums. Technical soaking of rotate movement and static soaking affects the skin microstructure matrix. This study aims to compare the quality of wet blue leather tanned by static soaking in a vessel and rotating in a tannery drum, particularly in terms of chrome uptake and thermal stability. The penetration time in the soaking experiment varied from 8, 16, 24, 32, 40, 48, and 56 hours. Meanwhile, the control was processed in a small-scale tannery drum with two hours of penetration time. Then, each sample was subjected to basification using HCOONa and NaHCO3. The results showed that all samples increased in weight and thickness after tanning. After penetration, wet blue leather tanned in a tannery drum performed better blue-green colour evenness compared with the soaked ones. Tannery drum leather also showed better chromium uptake, shrinkage temperature, and thermal stability. When the drum rotates, the pickled pelt gets mechanical action, such as being stretched, bent, and slammed, helping the collagen fibre open and the chromium penetrates deeper and faster. This study revealed that darker wet blue leather indicates higher thermal stability and chromium uptake.