An improved process for tanning fish skins

摘要

165,199. Knudsen, E. March 22,1920. Treating fish-skins; treatment preliminary to tanning; chrome tanning.-A process for tanning fish-skins, such as the skins of catfish, skate, &c., consists in salting the skins; liming in a. dilute solution, preferably softened with soda, the strength being progressively increased by additions of milk of lime; rinsing and, with or without puering, submitting to the action of a vegetable or chemical tanning agent which is only slightly acid or is neutralized. For chrome tanning, the skins are puered with weak chicken manure, then treated in a solution of sodium chloride to which hydrochloric acid is added gradually in increasing quantities. After soaking in soft water, the skins are then tanned in pure chromate in gradually increasing quantities, with or without the addition of hydrochloric acid. They are then washed in soft water and protected from the action of light, being subsequently treated with sodium thiosulphate, or with soda, and finally freed from acid by means of tepid water and chalk.