Leather tanning – How does it work?
Leather is stylish, timeless and durable and therefore a popular material for many beautiful products. But how does leather actually become the product as you know it when you buy it? In this blog you can read what kind of processing the material undergoes before you hold it in your hands. Most leather products are made from cowhide and calf hides. Such a skin consists of several layers: the epidermis (vein), the dermis and the subcutaneous connective tissue. To make usable leather, the hair and subcutaneous connective tissue are removed. The dermis remains and is made suitable for productions. You can read how that works here.
Preparing for the tanning process – washing and splitting
After arrival at the tannery, the hide is first washed for a day in a large drum and soaked with lime so that the hairs come off. The hides are also cleaned of manure, mucus and blood. The fat and meat residues are then scraped off in a fleshing machine with a sharply sharpened blade cylinder.
Cleaning done, tanning!
After this, the hide is tanned in barrels. Why is that necessary? If hides are not tanned, they would spoil over time. The barrels contain special substances to prevent this. They replace one part of the skin fibers for the tanning agent, so that bacteria no longer break down the skin fibers. This makes the skin resistant to decay.
Various substances can be used for this process. Nowadays, chemical tanning using chromium salts is widely used. This ensures a faster and more affordable process than before and it makes the skin nice and smooth.
It is also possible to vegetable tan the leather. The substance gallic acid is often used, the strongest antioxidant that can be found in nature. You can also find this substance in tea, wine, extra virgin olive oil and cocoa. Other natural tanning agents are so-called catechins. These antioxidants are also found in white tea, chocolate, fruit and many plants. Unfortunately, this process usually does not achieve the suppleness of chrome tanned leather. It is also a more expensive process.
After this, the top layer and bottom layers are split apart, because the skin is then still about 6 to 8 mm thick and therefore not suitable for processing. The smooth top layer is called grain and is the most beautiful and strongest layer of the skin. The bottom layers are called split.
After splitting, the hide is tanned a second time in barrels for the desired finish, color and suppleness. The sorted hides are now dyed and greased here. After dyeing, the leather is beaten smoothly and left to dry in the vacuum press (crust). The leather is now ready for finishing.
Last but not least – the finishing touch
Finally, the finishing layer is applied to the skin with, for example, a spraying machine. In this phase, designs or structures can also be applied to the leather using stamps. For example, you get fantasy leather with a crocodile or ostrich structure. The grain leather can also be sanded to achieve a very soft result. You know this as nubuck leather.
The entire process from arrival at the tannery to finishing to a beautiful end product takes about 3-4 weeks. That is why leather is a relatively expensive, but a natural and special material. No skin is the same and that is why you always have a unique product in your hands.