How to tan leather?

How do you tan leather?

There are 6 common steps in tanning leather. How to tan leather also depends on the type of hide and intent of usage, so these steps may vary.

1. Soaking
   Soaking is done to remove any excess salt or dirt. All non-leather making components should be removed from the hide to prepare for the production a clean and flat pelts.
2. Liming
   The goal of liming is to split the fibre bundles and to remove any unwanted hair from the hide through the introduction of alkali. Hair saving or semi-hair saving systems yield particularly good results. Here, lime is typically added before alkaline swelling occurs from subsequent additions of sodium sulphide and sodium hydrosulphide. This enables the lime to penetrate and diffuse evenly through the pelts, for optimal fibre splitting and separation. From this stage the skin is often referred to as a pelt.
3. De-liming
   The pelt requires an efficient and complete removal of lime and the neutralization of residual alkalinity, after fleshing and/or splitting. This is done most effectively using proprietary organic acids and acid-salts which form highly soluble lime complexes. Additional care must be taken to adequately buffer the de-liming bath and avoid the precipitation of soluble proteins through a rapid drop in float pH.
4. Bating
   The network of elastin fibers, which are insoluble in the highly alkaline conditions of liming, should now be evenly relaxed and flattened through the extended action of suitable enzyme preparations.
5. Pickling
   Acids are added to slacken the pelt and enhance penetration of the tanning agent.
6. Tanning
   By using a tanning agent the collagen structure of a pelt is being altered and converted into a leather intermediate. It is now a durable material and protected against chemicals, moisture and microorganisms.

Once a hide or pelt has been tanned, it is considered leather. It is however not yet ready to be used for the production of a leather item, such as a shoe, a bag or a leather chair. It will need additional treatment. The work processes following tanning are called wet end and finishing.

Overview of all the steps in leather making:

How to choose a tanning agent?

There a many different tanning agents. The best tanning agent for your piece of leather depends on the article type and desired usage of the leather. There are also regulations and environmental aspects to take into account. Around 80% of  leather is tanned with a chrome based tanning agent, but because chrome tanning is not the best option for the environment more and more brands and tanneries are looking for more eco-friendly options, such as Zeology, which is zeolite-based tanning. Zeolite is a natural occurring mineral in the Earth’s crust and produces leather than can be composted after use.

Read more about Zeology