Leather that stands the test of time
Twice a year at Paris-Nord Villepinte the major industries supplying materials and services, such as leather, to the global fashion industry come together in Paris at the Premier Vision exhibition. Premier Vision publish interesting newsletters about products and trends in the industry. A recent newsletter discusses the history, benefits and modern production processes for our beloved vegetable tanned leather.
Vegetable tanned leather
As discussed in the Premier Vision Newsletter no.7
It was already known in ancient times that treating hides with vegetable extracts would render them rot-resistant and allow them to be used for other purposes. In the 4th Century BC, the Sumerians, who wore mainly hides and pelts, described their tanning methods on clay tablets to pass their knowledge on to future generations. Six thousand years later, this same procedure is still being used and is appreciated for its natural ingredients and the beauty of the leather it produces.
Leather that stands the test of time
The principles of vegetable tanning have not changed since ancient times, still using the tanning properties of plant materials, mainly extracted from trees: oak, chestnut and mimosa, as well as quebracho and tara from Latin America. But whereas once the skins were hung to macerate in vats in direct contact with the bark, roots, berries and leaves for lengthy periods of time (up to 18 months or even two years), now concentrated extracts are used. These have optimal tanning capacity and have allowed maceration times to be considerably reduced.
In addition, the use of drumming not only makes the tanning more even, it also reduces the time required, as the mechanical action facilitates the penetration of the tannins into the skin fibres. Consequently, the duration of the vegetable tanning process now tends to be between 48 and 72 hours. “The use of hot water has also allowed us to shorten tanning times,” adds our correspondent from the Jullien tannery. However, the traditional vat-tanning procedure is still used to produce very thick and strongly rub-resistant leathers by companies such as the Belgian tannery Masure, which specialises in producing leather for soles from bovine butt hides.
The skins are immersed in a series of five to eight vats containing increasing concentrations of tanning solutions. They spend between 15 to 30 days in each vat, meaning that the complete tanning process can take three to eight months, according to the desired result. However, “with concentrated tannin extracts and drum tanning as a complement, we can reduce the tanning time to one month,” explains Philippe Alfonsi, managing director of the Fortier Beaulieu tannery. Once the hides have been tanned they are dried, preferably in the open air rather than in a tunnel, which further extends the production time but improves quality.
For vegetable leather, as is often the case with life in general, patience brings its rewards. When the vegetable-tanned leather has not been given a final finish that modifies its surface, it boasts a roundness and sensuality to the touch that delights real leather lovers. In addition, as it absorbs humidity better than other types of leather, it is particularly suitable for being in direct contact with the skin. The tanning agents give it a natural beige colour, with different plants giving different shades. Vegetable-tanned leather also takes some of the strength from the wood used to tan it, giving it good rub- and stretch-resistance.
However, one downside of this natural dye is that the leather cannot be given a white or pastel colour unless a finish is applied to the surface. Furthermore it tends to darken over time, as it is light-sensitive, an inconvenience that the defenders of this noble leather seek to play down by focusing on the famous patina that it develops as it ages. It is also sensitive to heat, which causes it to shrink or even to become breakable above 70°C.
But once again, its fans come to its defence by emphasising that, like all noble materials, it requires care and attention. And this ancestral and 100% natural tanning procedure is nicely in tune with the ecological concerns of today.
Uses and applications
Vegetable-tanned leather is strong and resistant and was used in industry for mechanical parts such as belts that were subject to great duress. Saddlery is also a very ancient application, as are the outer soles of shoes, which remains one of the emblematic outlets for vegetable leather in the luxury sector. But footwear interiors also benefit from its capacity to absorb humidity and it is often used for linings and inlay soles. Thanks to its strength and its suitability for contact with human skin, it is also recommended for orthopaedic items. These are often manufactured by moulding, a technique which is unsuitable for its chrome- or synthetic tanned competitors.
Similarly, it is used for upholstery where its patina is considered to be a sign of nobility and naturalness. But it is also benefiting from the boom in leather goods production thanks to the progress made by drum tanning, which makes it suppler and easier to handle. Handbags in particular are currently an important outlet for vegetable tanned leather, where it can be used as the outer or inner material.
A specialist leather
Vegetable tanning naturally gives a beige colour to vegetable leather. Samples from Fortier Beaulieu. For its large thick skins, destined for use as leather soles, the Belgian tannery Masure still tans in vats. Vegetable tanning can be used on all species of hide, but the technique requires very sound experience and expertise and is often the preserve of specialists who are entirely dedicated to the production of vegetable-tanned leather. Each has their own recipes, their own tricks and secrets that confer specific characteristics onto their articles.
Find out more about Premier Vision, Paris, here.