PROCESS FOR TANNING FISH SKIN

摘要

A process for tanning fish skin, which process comprises the steps of: a) introducing into the drum-tumbler or any other similar apparatus for the processing of skins, cold water in weight amounts variable between one time and eight times the weight amount of skins to be processed and an amount of salt variable between 2 % and 30 % by weight of the weight of the skins; b) putting said drum-tumbler into rotation for a time period variable between 2 and 45 minutes; c) introducing the skins into said drum-tumbler and let the drum to rotate for a period variable between 5 minutes and one hour; d) introducing into the drum-tumbler an amount variable between 1 % and 10 % by weight of the skins to be processed of a disinfectant having preservation properties with regards to said skins and which is compatible with the same, and causing the drum to rotate for a period variable between 5 minutes and one hour; e) introducing into the drum-tumbler an emulsifying agent in amounts 0.3 and 5 % by weight of the skins to be processed and causing the drum to rotate for a period variable between 5 minutes and one hour; f) unloading the whole amount from said drum-tumbler; g) subjecting the skins so treated to an internal cleaning action by removal of the flesh residues attached to the skins; h) weighing the skins so obtained; i) introducing the skins into the drum-tumbler together with an amount of water between 0.5 and 6 times as large as the weight of the skins according to the step h) and with an amount of salt such as to obtain a degree Baumé (B) of about 6.5; l) putting the drum into rotation for a period variable between 2 and 30 minutes; m) introducing formic acid progressively till a pH value is obtained between 3 and 4, and causing the drum to rotate further for a period variable between 10 minutes and one hour; n) introducing into the drum-tumbler while it is at a standstill an amount of chromium variable between 3 and 30 % by weight of the skins according to the step h); o) causing the drum-tumbler to rotate for a time variable between 1 hour and 20 hours; p) keeping the whole mass at rest about overnight; q) washing the same with running water; and r) arranging the skins so tanned on a beam or the like at rest for at least 36 hours. a