Tanning is the process of making ready or processing skins/ hides into leather utilizing tannic acid. The raw collagen fibres of the pelt are reworked right into a stable materials that will not rot. The principal difference between raw hides and tanned hides is that raw hides dry out to form a hard, inflexible materials that when re-wetted (or wetted back) putrefies, while tanned material dries out to a versatile form that does not become putrid when wetted back. The tanning process significantly improves the pure qualities of the leather reminiscent of its dimensional stability, abrasion resistance, chemical and heat resistance, its resistance to repeated cycles of wetting and drying.
Significance of Tanning
1. It protects the leather from being dehydrated- The tanning processes at all times make sure that the leather maintains its inside moisture.
2. It protects the leather from decaying when subjected to water- Chemical treatment 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 way 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 leather resist every kind of weather conditions.
5. It enhances the flexibility of the leather- Tanning makes the leather supple and soft improving its workability and moulding qualities. This makes it easy to be utilized in the production of leather articles.
Sorts of Tanning Processes
1. Vegetable-tanning: This tanning process involves using tannins and different ingredients present 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 colour, with the precise shade depending on the combination of chemicals and the color of the skin. It’s the solely type of leather suitable to be used in leather pieces for sale carving or stamping.
Vegetable-tanned leather just isn’t stable in water; it tends to discolour, and if left to soak after which dried will cause it to shrink, render it less supple, and harder. In scorching water, it would shrink drastically and partly gelatinize, changing into rigid and eventually brittle.
2. Chrome-tanning: This tanning process was invented in 1858. It’s the most widely used tanning process today. It includes the usage of chromium sulfate and other salts ofchromium. It’s more supple and pliable than vegetable-tanned leather and does not discolour or lose form as drastically in water as vegetable-tanned. It is also often called moist-blue for its colour derived from the chromium. More esoteric colours 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. Combination tanning: This is a tanning method that combines two or more of the above tanning methods discussed. Mostly, it’s a mixture of vegetable and chemical tanning. The pelts are first tanned using the chrome tanning approach and is later re-tanned using the vegetable tanning process. A mix of two tanning techniques is deliberately performed to achieve a really supple leather. Also, leather that is to obtain a finishing technique because of its last use generally goes by means of the combination tanning process.