TANNING PROCESS

PURPOSE:To produce a tanned skin having excellent quality in a short time in high efficiency by immersing untanned hide in lime, defatting the treated hide, immersing in a phosphate buffer solution and tanning the hide by adding an aldehyde. CONSTITUTION:An untanned hide immersed in lime is divided, washed with water, defatted in a solution containing a phosphoric acid salt and a defatting agent and then immersed in a phosphoric acid salt solution to form a buffering region of pH6-7 by the reaction of the phosphoric acid salt and Ca ion in the untanned hide. The hide can be tanned by adding an aldehyde to the above liquid. The aldehyde content of the tanned skin is increased, the thermal shrinkage temperature in the liquid is raised and the total time necessary for the treatment can be shortened by the increased reactivity of the skin and the aldehyde owing to the formation of the buffering region.