Leather is a highly versatile material, which is made from natural sources. It is extremely flexible and durable and hence it finds use in a large variety of things starting from garments like jackets, coats, trousers to accessories like gloves and caps to showpiece models and toys to shoes to many more things. But one may be curious about the methodology that goes behind the manufacturing of this remarkable material. Let us delve deeper into how leather is made.
Leather manufacturing is a long and laborious process and in most cases it is highly labor intensive, meaning there is a great deal of human element that is required in its manufacturing. It undergoes a long process before it is finally ready to be dispatched to manufacturers of leather goods. This process includes cottage industry and goes on to involve heavy industry as well.
Leather manufacturing is different for different kinds of leather. However, there are three basic stages that are involved in the entire process. These are: preparatory stages. Tanning and crusting. The preparatory stages mainly include cleansing the hide or the skin of the animal and getting it ready for tanning. The hide may be from reptiles like crocodiles or from sheep, goats, cows etc. The preparatory stages can include the following methods: preserving, soaking, liming, getting rid of the hairs, fleshing or cutting and splitting the body or the flesh, liming, re-liming and de-liming, getting rid of the greasiness, de-pickling and also bating. Each of these processes are critical to make sure the hide is properly prepared for tanning and leaving out any of these stages would mean that the hide is not ready for tanning.
Tanning is a crucial part of the process of manufacturing leather. Tanning is a process that aims at removing the protein from the hides or the skins, so that the hide becomes more stable as a material and does not putrefy when wetted or rewetted. This also happens to be the key difference between tanned and untanned hides – while the former will not putrefy even on wetting or rewetting, the latter will get putrefied on wetting or rewetting. So naturally tanned hides are more preferable, as they then can be used in a wide range of applications. And that is why tanning is such an important part of the whole process of manufacturing leather.
The most commonly used tanning material is chromium and chromium sulphate is also used. After tanning the material with chromium, the hide assumes a pale blue color and this is why it is called ‘wet blue’. Once the pickling process on the hides has been finished, the pH levels (which indicate the level of acidity or alkalinity of a solution) vary between 2.8 and 3.2, meaning that they are still highly acidic. Then the hides are put inside a drum, in which there will be the tanning liquor and the drum will be capable of turning about an axle. This will ensure that the tanning liquor gets uniformly distributed all over the hide.
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