Vegetable tanning of leather
To manufacture our entire range of Club chairs and sofas, we work in collaboration with a factory, located in Mazamet, in the Tarn region (81). This French family business, in existence since 1898, is a specialist in vegetable tanning.
For 4 generations, it has perpetuated a unique century-old know-how. Today, it is recognized worldwide.
The philosophy of this tannery is to offer high quality services, respectful of the environment.
It works with research and development laboratories to constantly develop new products and new manufacturing processes.
We invite you to discover their workshop and the different stages of the leather processing.
The advantages of vegetable tanning
The advantages of vegetable tanning are numerous.
First of all, it is a healthy process, safe for the health of the end user and the tanner, as no chemicals are used. There is no risk of allergies.
This method is less harmful to our Earth and more respectful of the environment because the tannins are derived from plants. Because of its environmental qualities and its harmlessness, it is called “ecological leather“.
The tannery also respects the REACH standard, certifying that the dyes and other products necessary for tanning are all validated by the French and European authorities in terms of safety and use.
It also has its own water treatment plant and uses a wood-fired boiler to heat its buildings. These actions allow the company to limit its carbon footprint as much as possible.
In addition to being natural, vegetable-tanned leather is very strong, absorbs moisture well and has a very good durability. It has the advantage of ageing well and becoming more beautiful over the years with a nice patina.
Thanks to its natural tones, it gives off deep and very nuanced colors, which makes the leather unique and authentic !
What is vegetable tanning ?
Unlike a tanner, who works with large skins (cows, calves, buffaloes, bulls, bullocks…), the shrewyer works with smaller skins (lambs, sheep, goats).
Both tanners and shippers use tannins to transform these skins into leather. This transformation operation is called tanning. It consists in making the hides rot-proof, durable, resistant to tears, water, high temperatures and abrasion.
Depending on the type of leather required, tanning gives them more or less flexibility or firmness.
There are two types of tanning: vegetable tanning and mineral tanning.
Vegetable tanning uses tannins from plants. These tannins are found in the bark of trees (oak, chestnut, mimosa, acacia …), leaves, seeds, roots or the sap of plants.
It was the first means used by our prehistoric ancestors to work the skins. Indeed, Man quickly understood the interest of transforming the skins of the animals he killed to clothe himself, to put on shoes and to build habitats to protect himself from bad weather.
Mineral tanning uses mineral tannins: chromium salts, iron salts, zirconium salts…
This technique, which is widespread throughout the world, is less expensive and faster than vegetable tanning, but is increasingly criticized. Indeed, these chemicals are very polluting and can cause allergies. What the industry gains in productivity and yield with mineral tanning comes at a cost in terms of product quality and environmental preservation.
Few factories still use the old technique, vegetable tanning, to work the skins.
Mon Fauteuil Club has discovered the benefits of this process and has adopted it for the production of its Club chairs and sofas.
The steps prior to vegetable tanning
Obtaining a finished leather is a long process that includes multiple steps. It is an ancient know-how that is now based on modern techniques and processes.
Before the actual tanning, there are two important steps: the skin working and the “river work“.
This second step consists of bathing the hides in a large volume of water. It was traditionally done directly in the river bed, hence the name.
The tannery in Mazamet is ideally located near the Thoré River, a very singular and chalky river, which was perfectly suited to this work. Today, this step is carried out in large vats.
The work of the skin
The work of the skin consists first of all in carefully separating the skin from the carcass of the animal with the help of specific tools. At this stage, we speak of “fresh skin”. These skins are extremely fragile and perishable. It is therefore imperative to prepare them quickly for conservation and future use.
75% of the weight of these skins is water. They degrade in a few hours. To stop the development of microbes and bacteria and thus this degradation, it is necessary to eliminate this water.
This is done by a first step of salting. Once the salt is removed, a drying stage takes place. At this stage, we speak of “raw skin”.
The skins are then sorted and classified according to their quality, their defects, their size, their weight, the sex of the animals…
Note here that the animals are not killed for their skin. The skin is a waste product of the meat industry, which is recovered and recycled by the leather industry. Without the leather industry, the skin would be just another waste product to be treated and disposed of.
The river work
The purpose of river work is to transform raw hides into hides ready to be tanned.
It consists in soaking the skins in order to :
- rehydrate them
- avoid their putrefaction
- clean them well
The latter still have wool, hair and impurities on their surface, on the epidermis side.
The soaking allows the depilation (destruction of the hairs and the surface epidermis) and the peeling (light degradation of the fibers to make the skin more receptive to the future tanning treatments)
This stage conditions in part the suppleness of the finished leather, because the more the fibers are degraded, the more the leather will be supple.
It is also at this stage that the “flower” is highlighted, in other words the appearance and quality of the hide.
The hides then go to the fleshing process. A machine (a scarfing machine) eliminates all the subcutaneous tissues on the flesh side.
Finally, the skin goes through a stage of abundant rinsing with water, then a last stage of dewatering.
At the end of the river work, of the original skin, only the dermis remains, ready for the tanning stage.
Vegetable tanning
Vegetable tanning is the operation that transforms the skin (free of hair and other residues) into leather, thanks to vegetable tannins.
The action of the latter makes it possible to pass from a putrescible skin, to a rot-proof and resistant matter.
This step consists of immersing the skin in large circular vats, called tannery drums, containing the tannins.
It is done slowly, over periods ranging from a few days to several months. It produces leathers that are often firm, perfect for making Club chairs and sofas. The leather obtained is called basane. The tanning process reveals all the nobility of this material.
At the end of this operation, it is now possible to speak of leather and no longer of skin.
Two last steps are generally added to vegetable tanning : the currying and the finishing.
The currying
It consists of several phases. First of all, a wringing, which is done with a press or machines with felt cylinders. Under the effect of the pressure, the leather loses a large part of its water content. Then, the hides are left to drain for 24 to 48 hours.
Then intervenes :
- the splitting: the leather is separated into two sheets, one is the flower, of uniform thickness (external side) and the other is the crust. It is the grain that is used in the making of our Club chairs and sofas.
- Scrapping to remove excess leather and unwanted parts
- Winding to finish drying the leather, stretching it and giving it a flat surface
- A second winding, called “retenage”.
- Palising to make it more supple
The finishing
At the end of these steps, it is possible to nourish the leather and give it the aspect and the color that you wish.
The food will bring a great flexibility and increase its lifespan.
To obtain a particular color, the leathers go through several dye baths, containing various dyes.
They are colored in a uniform way and more or less in depth.
Then, depending on the desired final result, the leather can be given a satin finish or a graining. It then passes between presses, with smooth or engraved and heated plates, to apply a pattern (surface wrinkles, artificial grain, drawings in relief, “crocodile” look …)
These aesthetic characteristics concern the shine, the color, the touch or the relief.
The leather is then transformed into finished leather.
