From skin to leather
How is leather made? Every step from the raw hide to the tannery work, to the finishing of the leather is described in this article. Treatment processes, vocabulary and illustrated explanations. Discover what vegetable leather is and the different grains of leather.
FES Morocco dyeing
1.1.3 Its characteristics
2.1 Leather grains
2.3 The suede
How does tanning work?
TTanning is the process that transforms raw animal or vegetable skin into leather using products* that make the material water repellent, rot-proof and pleasant to the touch. Tanning for large hides, and tanning for small hides.
Tanning has been going on for 50,000 years.
These products, called Tannins, are of plant or mineral origin such as chromium salts III, which have been used since the early 20th century.
A short introductory video: discover the treatment of raw skin, coloring. A commentcestfait.com video.
Decree the manufacturing process in this video.
It takes 16 hours to tan a cow's skin.
Among all phases, from the choice of skins to the preparation through the tanning to the finish, let's remember 6 steps:
- The Temper (or greening): Hydration. A clean-up step of sorts.
- Hair elimination : Hair removal Yespeeling: the hairs are removed. Without the epidermis, hairless and fat-free, the skins are ready to be tanned. 2 shares, 2 machines:
- River work In a rotating barrel, the mechanical action releases the hairs.
- Hair removal 2 rollers between which the skins have been hugged complete the cleaning.
- l’scramging Removing the subcutaneous tissue (see diagram below) using a machine called a scavenger.
- The Tanning literally
- The confiting The process to soften the leather.
- The picklage : Acidification of the skin for tanning.
- Tanning Dehydration and fixation of chemical agents
- In machines called treads, skins are Soaked, often in chromium salts (a classic process that opposes the plant method)
Subcutaneous tissue (Credit Noémie Daval)
The vegetable tanneriesExplanations.
Leather Plant Is it from the plants?
Cat the beginning of the article, the process was more Ecological favouring "natural" tannins allows you to produce a "vegetable" leather: bark, wood, roots, leaves or fruit.
At the industrial level, the following plant tannins can be listed:
- excerpts from québracho, Mimosa Yes chestnut tree for plant tannins
Vegetable leather comes from animals, and the term should not be confusing. It is not a leather from plants or plants.
Historically, this process requiredprocessing time important, especially for maceration. Instead, it was necessary to count Month only in days. That is to say... we probably didn't talk about ecology, or very little then. Was it known only whether inhaling leather products could interfere with Health ? And do we know that anymore? It is recognized, however, that chromium is not the most healthy.
The machines have reduced the delays. The Tanks And Pitsare part of the heritage and have given way to tramps (or treads) Circular more effective.
The trend towards a return to ecology
Treatment Purely Plantwould be less common in the industry today. It would not meet the requirements of trade, in terms of the flexibility of the final product in particular. The processing time, which is prohibitive for profitability, would undoubtedly contribute not to favour this choice. All of these arguments seem to be fuelled by lobbyists. There is a whole history of plant mégisserieIn France. In some regions such as the Mazamet, on the Castres side, the shoe leather, for the sole (first leather) and the lining has long been produced by plant techniques and therefore naturally respectful of the environment. Unvalued, these treasures of know-how are in danger of dying.
Vegetable tanning accounts for 10% of global production. Historically, it was not until 1850 that chromium tanning techniques developed. Basic chromium sulphates (trivalent chromium, Cr III) are said to mineral tannins.
L'Luxury industry however, seems to be turning to "clean labels"to guarantee its customers leathers that respect the environment. Times are changing and fortunately, we can hope for a virtuous rebirth of these techniques. It is up to everyone to be attentive and to be interested in the origin of the materials. Let's mention the label BASANE LBwho unfortunately failed to impose himself and who wanted to put forward an environmentally friendly charter on the leathers of mégisserie (small skins), the ovids like sheep for example.
Another measure related to reassurance, REACH standard(European regulation). All megisseries must follow French and European legislation on classified facilities for environmental protection (ICPE). In the end, French leather is supposed to protect users of substances dangerous to health. More information Here.
Even if we talk about respect for the environment, standards and controls, are tanneries more environmentally friendly? Mineral tanneries still make use of a chemical treatment (mineral tannery, treatment with chrome salt). Information does not filter easily, not in detail. Sensitive subject. The French tannery federation mégisserie is able to provide you with more information about standards and regulations. The Leather Technical Centre, CTC in Lyon, also has a documentation centre.
"Tanneries usually use several hundred chemicals. The tanning operation represents only about ten products" Thierry P., CLC
"Generally speaking, buyers look for leathers based on their properties. Vegetable tanned leather and chrome tanned leathers have quite different properties. Then they check the environmental aspects" Thierry P., CLC
In particular, we know that tanneries claiming to be plant-based consume more water. Total respect for the environment is not easy in this regard.
pits and vats of plant tanning
Modern Fouloir (Credit Noémie Daval)
Fewer chemicals, therefore, more environmentally friendly, also offering safety qualities and anallergic. Natural skin sweating against leather should alert you to the risks of spreading harmful products. This vegetable leather is tannedBark, Fruit, Roots, Leaves. In return, the material is less flexible and elastic. These denser leathers are reserved for "wear" parts such as shoe soles or machine straps. We also think about uses that highlight its good performance in relation to the absorption of moisture.
Vegetable tanning leather offers a stiffer, firmer and stronger material. He has a good hold and he has a better moisture absorption. It also has natural hues that allow for deeper and more nuanced shades.
For soft leather, sought after in leather goods or furniture, vegetable tanning allows to find light brown colors and a pleasant smell. Less flexible and less elastic than chrome tanned leather, it can degrade under the effect of light with browning over time.
If you have the green fiber, if every gesture counts, then choose vegetable leather. In the end, it is the man who wins, and the manufacturer first.
Vegetable leather shoes
The eco-friendly tanneries in France
Tannerie in the country of Rennes, Trublet
DFrench tanneries such as Tanpuy favour these processese vegetable tanning instead of the heavy metal process (such as Chrome).
Vegetable tanneries, listed thanks to the filter "vegetable" thanks to the directory of tanneries megesserie (for small skins favoring tanning with mineral, vegetable or combined salts).
A list of French tanneries provided by "leather interiors" for the promotion of leather: http://www.interieurs-cuir.com/partenaires/coordonnees-39-1.html
Among these tanneries, one of them still existed in 2015, at the time of a fire that ravaged everything. My activity echoes an emblematic building of the canal located next to my workshop. Iat the end of the 19th century, tanneries closed in 1948.
Former tannery of the Canal Saint-Martin in Rennes.
L'Aspect final leather
Anear the manufacture of leather skins, the surface is smooth. The treads cause a natural grain of skin to lose. To explain the Granular, the megissier (small skin tanner in a way) recreates the grain. All is not lost, however. The original animal will dictate the ability of the material to regain a certain relief:
- Leather Cow or cattle is recognizable by a big grain, typical of sofas.
- Leather Calf is much more End, so more fragile.
The look Crumpled (see 2nd image in column below), is obtained in a dry scar.
different grains of leather (Credit AnneCecileCreation)
Leather is above all a pleasure for the eye and the touch. On the internet, we will be enough images of the skins. Rough, smooth, grainy or soft, it makes you want to touch!
different grains of leather (credit anneCecileCreation)
Depending on the animal and the techniques, the rendering is more or less grainy, marked. It is even possible to imitate reliefs. The operation is called the graining : The leather is pressed between two plates.
Leather graining (Credit Noémie Daval)
Look at this leather that would imitate I would say the ostrich. In this case, tinted leather is placed under a Press trays Heated 70oC with a drawing of graining. Needless to say, the pressure is high and the delays and temperatures jealously guarded the preparers.
Blue leather-looking Ostrich (Credit AnneCecileCreation)
What is full-flower leather?
La Mercedes leathers would say some. Particularly noble and precious in appearance and so pleasant to the touch, the full flower leather has its preserved top layer: the dermis. Without her hair, it is therefore the most aesthetic part when undressed from her coat. The skin is removed from the skin and its thickness is retained. The tanner seeks to enhance this leather by working on its small natural defects, traces of time and the aggressions of nature.
Full flower leather with engraving
We name the most beautiful leathers, the ones that Naturally retain an immaculate appearance, full-flower leathers Aniline. Without protective layer it can age in the sun, it is less resistant to fat stains because of its porous texture. Think of a product to protect it. Soon, a post on the products on the blog CREATIONACC. A soft cloth and a natural product with wax and jojoba oil like the "balm of life" do wonders in the meantime. I use it as much to clean my leathers and to preserve them from the passing of time.
The vegetable leather offers, in addition to its intrinsic qualities of use, an ability to beautifying as we get older. If you're looking to live with an old beau, choose a green one!
What is suede?
Le Suede Like nubuck are 2 finishes obtained by grinding or sanding soft. The nubuck is treated face down. The suede corresponds to the inner face, giving a more velvety appearance. We also speak of suede material (English term for deer for that matter).
pink suede leather (credit anneCecileCreation)