Animals as source of leather, Process and steps used in leather industries

 

Goat , Sheep Cow Buffalo, lamb,  snake, tigers crocodile etc are used  in leathers industry.

Remember👌👌The skin of cow is called as kips whereas the skin of Buffalo is called buffs.

Process of skin industry

Flaying -The traditional job of flaying is done by the hereditary peoples. During the process of flaying, some amount of flesh and tissue is attached with the skin to increase the weight of leather. This is also useful when a knife is used to cut the skin.The carcass is hanged with a pole with the hind limb upwards and peoples pulls the skin over the back of dead animals with its left hand. Now it is ready for processing or curing.

Curing - Due to atmospheric temperature and presence of bacteria and humidity, flesh and tissue associated with skin start to decompose soon and swelling of skin occurs in just ten to  twelve hours. The bacteria work on flesh and fat and make them in liquids but this bacterial action must be stopped by the use of antibacterial agents.

Salting - The cured skin now treated with salt. Sodium sulphate, sodium chloride and potassium nitrate are  commonly used salt  for this purpose. These salt is sprayed on fleshy surfaces of skin. Now the salt treated skin is sent for the tanning. 

Tanning- It can be summarised in to pre-tanning , tanning and post tanning.

Pre-tanning process consist of various steps like soaking, liming, scudding, Deliming, pickling.

Soaking -The crude skin are soaked in water for saveral days to restore the flexibility and to remove the extra tissue. Now it is soaked in caustic soda or sodium sulphide in wooden drum.

liming - Soaked skin is now immersed into lime to solublise the epidermis and attach hairs. The lime liquor dissolves mucin. 

scudding - The limed skin is unhaired with the help of knife of unhairing machine. The fleshed skin is now studded by applying a force to take out the remaining of tissue, pigment etc.

Deliming- The Residue of lime is removed by treating of weak acids or acid salt. The skin of lamb and calf are delimed completely for the production of leather of best quality by vegetable tanning.

Pickling - The delimed skin and hides are pickled in drum containing solution of sulphuric acid. It is also called as bath process. Pickling makes the skin uniform with clean surface.

Tanning - The pickled skin is treated with tanning agents like basic chromium sulphate, basic salts of aluminium, zerconium, quinone, fish oil etc. Tanning is of three type-

Vegetable tanning- The delimed skin are immersed in tank containing mellow tan liquor which is rich in non tannins and organic acids which remove last trace of  lime from pelt or skin. Now pelts are treated with liquor of different strengths. The vegetable teenage is used for the production of sole, belt, saddlery etc.

Chrome tanning - It is done with the use of basic chromium sulphate . The chromium sulphate and sodium thiosulphate are used for making upper leather of shoes and other soft leather goods.

Oil tanning - The chamois leather is prepared from the sheep skin by an oil tonnage. The fish oil is used for the this purpose.

Post tanning - After the tanning,  skin is subjected to a number of mechanical chemical and physical process. These process are removal of water, tan liquor, splitting, bleaching, dying,  drying,  buffing to get fancy touch of leather for commercial purpose.

Enemies of skin industry- Warblefly and ticks are prominent enemies of skin. Warblefly makes numbers of hole on skins and decrease the economic value of leather. Tick are also found  damaging the skin and hides. Tick is responsible for almost thirty percentage of leather in leather industries.