Tanning is the process of preparing or processing skins/ hides into leather utilizing tannic acid. The uncooked collagen fibres of the pelt are remodeled into a stable materials that won’t rot. The principal difference between uncooked hides and tanned hides is that raw hides dry out to form a hard, inflexible material that when re-wetted (or wetted back) putrefies, while tanned materials dries out to a versatile type that doesn’t develop into putrid when wetted back. The tanning process significantly improves the pure qualities of the leather similar to its dimensional stability, abrasion resistance, chemical and warmth resistance, its resistance to repeated cycles of wetting and drying.
Significance of Tanning
1. It protects the leather from being dehydrated- The tanning processes all the time ensure that the leather maintains its inner moisture.
2. It protects the leather from decaying when subjected to water- Chemical remedy of leather which is a part of the tanning process prevents the leather from going bad on account of rotting.
3. It makes the leather porous- Working on the leather by means of the tanning processes opens up the leather so that it turns into airy and absorbent.
4. It drastically improves the tensile power of the leather- Tanning builds up resilience in the leather. This makes the wholesale leather resist every kind of climate conditions.
5. It enhances the flexibleness of the leather- Tanning makes the leather supple and soft improving its workability and moulding qualities. This makes it straightforward to be utilized within the production of leather articles.
Sorts of Tanning Processes
1. Vegetable-tanning: This tanning process entails the usage of tannins and other ingredients found in vegetable matter derived from wood and plants. Examples include chestnut, oak, redoul, tanoak, hemlock, quebracho, mangrove, wattle (acacia), and myrobalan. It’s supple and brown in color, with the exact shade depending on the combination of chemicals and the color of the skin. It is the only form of leather suitable to be used in leather carving or stamping.
Vegetable-tanned leather will not be stable in water; it tends to discolour, and if left to soak and then dried will cause it to shrink, render it less supple, and harder. In scorching water, it’ll shrink drastically and partly gelatinize, becoming rigid and eventually brittle.
2. Chrome-tanning: This tanning process was invented in 1858. It’s the most generally used tanning process today. It includes the usage of chromium sulfate and different salts ofchromium. It’s more supple and pliable than vegetable-tanned leather and doesn’t discolour or lose shape as drastically in water as vegetable-tanned. It’s also known as moist-blue for its colour derived from the chromium. More esoteric colors are possible utilizing chrome tanning.
3. Mineral Tanning: In mineral tanning, the pelts are soaked in mineral substances normally the salts of chromium, aluminum and zinconium.
4. Oil Tanning: In this tanning process, the pelts are soaked in sure fish oils which have a tendency to provide a very supple, soft and pliable leather like chamois.
5. Mixture tanning: This is a tanning technique that combines or more of the above tanning methods discussed. Principally, it’s a combination of vegetable and chemical tanning. The pelts are first tanned utilizing the chrome tanning technique and is later re-tanned using the vegetable tanning process. A blend of two tanning methods is deliberately done to achieve a very supple leather. Additionally, leather that is to obtain a finishing approach because of its last use typically goes by means of the combination tanning process.