OFFAL TREATMENT PROCESS Russian patent published in 2000 - IPC

FIELD: leather industry. SUBSTANCE: invention relates to processing of cattle and small cattle skins that can be used for manufacturing leathers for uppers, clothes, and haberdashery goods. Offal is treated for 5-10 min with ammonium sulfate solution in amounts of 14-16% based on the weight of offal. After that, offal is pickled with sulfuric acid, formic acid, and sodium chloride solutions and then tanned with basic chromium salts in two steps: at low and high basicity. Tannage is carried out for 6-7 hr at 35-40 C with water uptake 30% and chromium salt (on conversion to oxide) uptake 2.5-2.9%. EFFECT: reduced consumption of chromium salts due to their more complete absorption from tanning solution. 2 tbl