The Premier Vision Show twice a year in Paris runs a leather show in an adjacent hall. It is always interesting as France is a centre for the manufacture of luxury products, the great majority of which are based on traditional craftsmanship using leather. Considerable efforts have been made to keep these crafts alive in France and the tanneries that supply them.
Earlier this year the show produced one of their interesting newsletters – their no 7 – that focused on vegetable tanned leather. This blog is based on it, and for those interested to delve further, a link to the original is attached at the end. There is quite a lot about the individual tanneries who show at the Fair.
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, today mainly extracted from trees: oak, chestnut and mimosa, as well as quebracho and tara from Latin America. But whereas once the skins were hung 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. This is much faster and only tanners of authentic oak bark leather stick to the rule of the leather being tanned for one full year in the pits.
Many tanners today mix pits with the more modern process of drumming, which shortens the process time even more. The article suggests that drumming can shorten the process to 48-72 hours and makes the skins more even, but certainly for bovine vegetable tanned leathers to be seriously used for other things than linings tanners still prefer to use mostly pits and stay with about three months of processing. For thicker hides, too much drumming damages the grain and the look of the leather. Working with thin skins like sheep or goat where getting the initial penetration is much easier, will allow for faster processing, and will also depend a bit on the end use in mind for the leather.
The article notes that the French tannery Jullien, which makes goat leather, also suggests that heating the water will help speed the process. This is true if it is done with care and at the correct stages. On the other hand, the Belgian tannery Masure which makes heavy bovine leathers, including thick butts for soles, has stayed with the more traditional pit process. The Masure tanning process can take between three and eight months.
Philippe Alfonsi, head of Tannerie Fortier Beaulieu, which also makes bovine leathers is quoted in the article on how they move a bit faster. “With concentrated tannin extracts and drum tanning as a complement, we can reduce the tanning time to one month.”
Once the hides have been tanned they are dried, preferably in the open air (not outside) rather than in a tunnel. Hanging in a shed allows slow drying that further extends the production time but improves quality.
For vegetable leather, as is often the case with life in general, patience brings its rewards. The natural leather, surface oiled and polished, 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.
Furthermore, vegetable tanned leather will darken over time, as it is light-sensitive. Perhaps this be an inconvenience but the defenders of this noble leather seek to play it down by focusing on the famous patina that it develops as it ages.
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 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 are currently an important outlet for vegetable-tanned leather, where it can be used as the outer or inner material.
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, and most top quality leather goods buyers like to see the natural grain.
A specialist leather
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.