Leather tanning is an ancient art that has been practised for more than 7,000 years. Its origins began with drying the hides in the sun, softening them, and then preserving them using salting and smoking techniques. As a craft, it’s something which has been perfected over centuries.
Despite its age, the process of tanning leather isn’t common knowledge. As such TORRO are at hand to answer all questions you have about the leather tanning process.
What is Leather Tanning?
At a simple level, leather tanning is the process of converting animal hides into leather. The process creates strong, flexible and long-lasting leather that can be used in many ways.
As animal hides are made of organic material, there is a strong chance that they would break down - eventually falling apart completely. Tanning leather helps to preserve the materials, preventing them from decaying. This allows the material to be long-lasting and durable.
Before the tanning process can begin, the animal hide needs to be prepared to preserve it. There are numerous ways in which this can be achieved.
Salting is one of, if not the most important aspect of preparing leather for tanning. This is generally done in one of two ways. Either by pressing the salt into the hide; or by placing the hide in a brine solution.
When the leather reaches the tannery, it's soaked in water to remove the salt - so it doesn’t completely consume the hide.
Liming is an important aspect of the pre-tanning process. It involves applying an alkaline solution to the hide to loosen the top skin, hair and natural materials. They can then be removed more effectively, allowing for higher-quality leather.
There is also a de-liming process, which is used to keep the hide supple.
Pickling involves adding acidic chemicals to the hide that will make microscopic inroads into the hide, allowing the tanning process to be done more effectively.
The bating process is used to soften the animal hide. When adding chemicals to the hide it can sometimes cause it to harden. This hardening prevents the chemicals from penetrating the hide as efficiently. The bating process helps ensure that the animal hide remains as easy as possible for tanners to work with.
A simple step entails adding water (or another solvent) to the hide to draw out any remaining grease.
With the animal hide prepped, tanners can begin the leather tanning process. At present, there are two main methods of leather tanning – chrome tanning and vegetable tanning.
Chrome tanning is the most recently created method of the two. Typically, it will be used in large-scale tanning operations featuring machines designed to allow more acidic tanning agents to penetrate the animal hide.
The hides are placed into acidic salts to loosen and then placed into the chromium tanning agents. This process can be completed reasonably quickly (often around a day) and as such is the more common type of tanning in the current era.
Vegetable tanning is a method which has existed for a long time. It is believed to have first been used by Ancient Egyptians over 5,000 years ago to protect hides they used for clothing and shelter. Over time the process was refined until the Romans later regulated the vegetable tanning industry.
The hide is placed into the tanning agents and left for weeks (sometimes even months). The tannin blend is based on the colour, strength and feel of the desired leather.
Vegetable tanning is considered more of a "craft" than a manufacturing process. The slower process means that the original grain of the hide is better preserved. It is through this tanning process that the distinct leather smell comes from.
It’s the popular choice for those who seek longer-lasting, higher-quality leathers - that develop unique patinas over time - just like the TORRO range of leather accessories.