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The Tanning Process

The Tanning Process

traditional tanner with old machines in workshop

Leather making has been around for thousands of years and can be traced back to ancient civilizations. Even as leather making evolves, the durability and desirability of leather remains. Leather is incredibly versatile, used for clothing, shoes, furniture, and any number of other products. It can be molded into any shape or form, making it utilitarian as well as stylish.

If you have ever looked at your favorite leather boots or purse and marveled at the craftsmanship, then you may have wondered – how on earth is this made? The modern commercial leather making process includes three primary stages:

tanner fleshing leatherA traditional tanner fleshes a hide with hand tools.

Preparation for Tanning

This stage is sometimes referred to as cleaning or “beamhouse” operations. A pelt is soaked to remove all water-soluble materials and return it to its original shape and softness. Next, it is soaked in an alkaline solution that removes grease, fat, and keratin, while loosening the hair. This soaking is called “liming” and it prepares the pelt to be fleshed before the hair is removed. Sometimes the hair is left on if the final product calls for it. Finally, the pelt is delimed and degreased. At this point in the leather making process the pelts haven’t been stabilized and can’t be stored for too long. 

wooden tannery drum or trommelA wooden tanning drum, or trommel.

Tanning

This phase stabilizes the pelt, making it durable, resistant to putrefying, and ready to be dyed. The name “tanning” comes from tannin or tannic acid which displaces water from the hide’s protein fibers and binds the fibers together. There are multiple tanning methods, such as vegetable, chrome, brain, and synthetic tanning. These days, chrome tanning is the most popular method and accounts for about 75% of all leather produced. This is largely due to it requiring significantly less tanning time and resources than older methods such as vegetable tanning. Each method’s process varies though they all create long-lasting and sturdy leather.

Fun fact: tanning allows the leather to withstand water that is 212°F without shrinkage.

shot of tanned leatherLeather after the tanning process.

Processing Tanned Leather

Once the leather is tanned, there is still a series of steps before it can be manufactured and sold. Immediately after tanning, the leather needs to be fully dried. Afterwards, it is neutralized with alkali and dyed, with the common methods being drum dyeing or staining. When the desired color is achieved, a blend of oils is then applied to lubricate the leather, making it softer, stronger, and more water-resistant. The leather is then dried to remove water and stabilize the chemical properties. The very last step is to add a surface coating that makes the color and texture even and wearable.

Leather making is a lengthy process that continues to evolve and improve. Regardless of which methods are used, each stage requires great care and attention to create the highest quality leather possible!