It involves soaking the hides in baths containing acidic salts until they are ready for the next step, chrome tanning. There are many ways to tan hides, but the end result is that the hides will not putrefy and are ready for dyeing and other uses such as manufacturing goods.Ĭhrome tanning is a relatively recent method of tanning, but easily the most dominant. Tanning ProcessĪfter the preparation stage comes the tanning. This process uses solvents or water-based systems to remove excess grease before tanning. This process is important because it prepares the collagen for maximum penetration of the tanning agents in the tanning stage.ĭegreasing comes next. The salt prevents the adverse effects of a sharp increase in acidity from the acids used in pickling. Bating involves the addition of enzymes to the hides to soften them.Īfter bating is pickling, which involves treating the hides by salt and then acid. The hides can then be bated, depending on the intended use of the leather. The deliming process can take about 2 hours for cattle hides. The swollen fibers of the hides shrink once more in preparation for the bating process. Next comes deliming, the step in which the alkalinity of the hides is reduced by adding acids to the hides in a drum or pit. After applying unhairing agents like sodium hydroxide and calcium hydrosulfide, most of the hair is then removed, first with a machine and then by hand using a dull knife. Unhairing follows fleshing, which sounds exactly like what it is the removal of hair from the hides. This process, fleshing, involves removing connective tissue and meat residue from the flesh side of the skin. It also causes the swelling and splitting of fibers to the desired extent and prepares the collagen in the hide to a condition that is ideal for tanning.Īfter liming, the pelt goes through a machine to remove fleshy tissue from the flesh side. Liming results in the removal of natural grease and fats as well as keratin and hair. This means soaking the hides in a drum or pit filled with milk of lime, an alkaline solution. This process involves soaking the skins in water which has certain chemicals added to prevent bacterial and fungal growth.Īfter soaking, the hides and skins go for liming. The first step is to remove the salts left over from the curing in a process called soaking. The steps after curing are called Beamhouse operations. Another way is to soak them in a saltwater brine for about 16 hours. One way to cure the skins is by wet-salting, in which the hide is heavily salted and then pressed into packs for up to 30 days. It greatly reduces the moisture content of the hide. Curing prevents putrefaction by preventing bacterial growth on the hide between procurement and processing. The next step is to cure the hides with salt. Once the hides arrive from the slaughterhouse or farm, the next step is to remove any scraps of flesh from them. The stages before tanning may include fleshing, preservation or curing, soaking, liming, unhairing, splitting, deliming, bating, degreasing, bleaching, pickling, and depickling. Preparation For TanningĪnimal hides go through several stages before they are ready for use in making products like belts, wallets, shoes, furniture and clothing. Tanning of hides for leather has been done for thousands of years by ancient civilizations like those in Sumer and India. The change depends on how long it takes and the tanning agents used. Tanning also changes the appearance of the hide. The main difference between tanned and untanned dry hides is that untanned hides will putrefy after getting wet, while tanned leather will not. The tanning process stabilizes the protein of the raw hide or skin, preventing putrefaction, and preparing it for a wide variety of end applications. Tanning is necessary for leather because if the raw hide is not tanned, it will rot and putrefy. We’ll look at the tanning process and discover just why the kind of tanning done on the hide impacts the final result so much. Ever wondered about the steps that go into producing the leather for that product you bought? The production of all leather involves several steps, from drying and curing to tanning and dyeing.
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