What is the Leather Tanning Process?
Leather is probably one of the most versatile and well-known materials in the world. Having been around for centuries, leather is used to make a variety of product, from clothing, bookbinding, furniture covering, accessories, and so on. Leather comes from animal rawhide and skin and often undergoes the tanning process to produce an end product for commercial and manufacturing uses. Leather can come from the skin of cattle, where majority of leather comes from, lamb, deer, goat, kangaroo, snake, and a lot more. By undergoing the tanning process, leather can be transformed into different kinds such as vegetable-tanned leather for bookbinding, aldehyde-tanned leather for making shoes for infants and automobiles, synthetic-tanned leather for accessories and clothing, and chrome-tanned leather, which is the most popular and sought-for type of leather tanning. With different sources, where rawhide can come from, and the variety of tanning processes that a leather can undergo to, it is no doubt that leather is one of the most useful products in this world.
Guide of the leather tanning process
So how exactly is the leather tanning done? Although there are different types of leather tanning, the basic steps of doing this remain the same. Let’s take a look at the usual steps taken to tan leather.
- Pre-tanning: Upon arrival at the tannery, or where the leather processing takes place, hides have to be soaked first to extrude the salts that were used to preserve the leather. Next is the liming process where the hair and epidermis are removed from the hide. A solution of sodium sulphide and lime are applied then to hide to soften and enhance it further for the end product. The hide is then split into layers – the top, which will produce fine and smooth grain leather, and the bottom, which can be utilized for suede.
- Tanning: After pre-tanning the hide, the formal process of tanning to convert the hide into leather begins. In this process, alkaline chrome-3 salts are used to penetrate the hide fairly quickly, around 24-48 hours usually. This tanning results in a fine, soft, and modern finish, which is basically what manufacturers look for to create an end product. In case the alkaline chrome-3 salts are unavailable, several tanning methods are available to tan the hide for leather production. Such methods are pure vegetable tanning, synthetic tanning, oil tanning, and combination tanning.
- Selecting: When the tanning process is done, the excess water from the hide will be removed. The hide will be graded then according to quantity and where the natural features and flaws can be seen in the product. Those that are heavily coated or embossed are usually a lesser quality among the hides that were tanned.
- Dressing: This process involves shaving, where hides are given the same thickness; dyeing, to add an additional colour to the leather, usually whatever the buyers or manufacturers require; re-tanning, when an additional tanning substances are needed to further beautify the leather depending on the consumer’s needs; setting, which is a process of mechanically removing the creases and excess water in the hide; drying, where hides are dried, by vacuum or by stretching them on large frames to dry; and trimming, where uneven coarse and untidy edges are removed from the rest of the hide.
- Finishing: In this last step of the process, hides undergo a combination of surface coating techniques to achieve the required physical state of the hide. These techniques include padding, spraying, roller coating, buffing, staking, and embossing. These finishing touches are usually done to lessen the grain blemishes in the hide without losing the natural appearance, and beauty, of the leather product, to provide the needed degree of gloss, to create a more protective surface in the hide, to ensure that the leather is soft and mouldable, to make the surface into something that can be easily cleaned, and to give the hide a special effect such as a vintage look.
Although it involves a rigorous process, there is no doubt that the tanning process creates a material that is beautiful, timeless, versatile, and well-loved by many. Leather is a material that can be used foranything and anywhere, that though trends and style may come and go, the versatility of leather will remain the same throughout the years. From furniture use such as chairs, home accents, and tables, to fashion mainstay for bags, accessories, and even clothing, to bookbinding and covering, and other uses for manufacturing, leather is a durable product that can last anyone for years. One just has to remember the proper ways of cleaning their leather goods, such as maintain the right moisture of the product, cleaning it on a regular basis, and not sealing it in plastic, to maintain the durability, beauty, and versatility of this great product.