How leather is processed

Principle

Tanning of leather is the chemical and physical processing of the proteins within the hide with tanning substances. It is through a series of processes, and the use of a number of chemical agents, so that cattle, pigs, sheep and other animals within the raw skin of the proteins undergo a series of changes, so that the collagen denaturation effect. The tanned leather is both soft, firm, and wear-resistant, and is not easy to rot and deteriorate. So the tanned leather can be used to make a variety of leather daily necessities. This experiment according to the conditions of secondary school, only introduce the easier to master the tanning process.

Operation

(1) 500g of dry animal skins soaked in a bucket of water to soft (about 3 to 5 days).

(2) Take out the softened skin, spread it on a flat surface, hair side down, and use a spatula to remove the meat and oil attached to the skin. Then take 300g of saturated lime water, add 50g of sodium sulfide, mix well, made of dehairing liquid. Dip a brush into the dehairing liquid and brush the hairy root of the skin plate, brush as evenly as possible. Then fold the skin, after about 3 to 4 hours, the hair on the skin is easy to fall off, then use a spatula to remove the hair completely.

(3) Immediately after dehairing, put the skin in running water to rinse, remove the vast majority of lime, sodium sulfide, and then soaked in water for 1 to 2 days.

(4) Prepare an iron pot, add saturated manganese nitrate solution of about 2L, slightly heated to keep the solution temperature at about 40 ℃. Remove the skins from the water, wring them out and put them into the pot. Knead the skin constantly with your hands, and so it is basically "full" of manganese nitrate after taking out, dry, about half an hour and then the second and third "eat nitrate", the same method as the first. 500g dry skin can "eat" about 250g nitrate. 500g dry skin can "eat" about 250g nitrate. Eat nitrogen after the skin drying to remove the floating nitrogen on the skin.

(5) another iron pot, add 500g of oil (will not be all used up), heating so that the oil temperature is maintained at about 40 ℃. The "eat nitrate" after the skin into the warm oil, push and pull with your hands, so that the oil and the skin constantly in contact with the skin, evenly seeped into the skin plate. "After eating enough oil, dry the skin on a wooden stick and let it dry naturally.

Instructions

The purpose of the lime and sodium sulfide mixture is to make the skin easy to remove hair, so just paint the hairy side. The liquid is damaging to the leather board, and should be washed and brushed immediately after dehairing.