Leather working is one of the oldest forms of craft. Though traditional and lengthy, mechanization has made the process less labor intensive now. However, it still consists of a series of time and energy consuming treatments, with the whole purpose of altering the protein structure of the skin to increase its durability, texture and appearance.
After the hide is cured with salt to remove water, there are four fundamental steps that leather has to go through, as below:
1) Preparatory Steps- Before being tanned, the animal hide needs to be prepared so it is soaked in water to restore the water lost during salting. The hide is then pelted to remove flesh, muscle and fat, and then again soaked in acids and salts to prevent decomposition.The preparatory step also involves liming and de-liming to reduce the swelling. The hide is then de-greased to remove fatty acids from the skin. Finally it is bleached to make the hide colorless to add the desired colour at a later stage.
2) Tanning- The main motive of this process is it to produce non-decomposable and sturdy material from the raw animal hide, called leather. Tanning actually converts the protein of the hide into a durable material. The most common processes include mineral tanning, vegetable tanning and glutaraldehyde tanning.
Mineral tanning is the most popular form of tanning as it is quicker, affordable and less labor-intensive.
3) Re-Tanning- The process of converting tanned leather into a marketable product is called re-tanning. At this stage, the leather is dried to remove excess water, and then it is split into one or more horizontal layers. The leather is further dyed, more often with soluble dyes. Finally, fats, oils or waxes are added between fibers to make the leather soft and flexible.
4) Finishing- This is the final stage where finishing touches are added to leather. It starts with polishing to create a shiny surface. Then it is embossed using heated hydraulic or roller presses. Furthermore, colour and designs are added to leather. Finally, it is graded before it is dispatched to the customers.
So, you can go with your new found knowledge of leather making and be more discerning while you buy leather. However, if you have queries, we would be happy to answer them!