Real aficionados of leather appreciate the most natural versions of the product, with its inimitable grain and texture. But what is a truly natural leather? And what are its limits? To answer these very important questions, we spoke to experts in producing the most authentic leathers. Precision and clarity were the watchwords.
It is the finish that determines the extent to which the leather is natural. “There are three types of finish: aniline, semi-aniline and pigmented or covered,” says Christian Bardes of Stahl France, supplier of chemical products to tanneries. “Leathers that can be described as “pure” are those with an aniline finish. This finish only adds colour, using a substance that provides colour but not coverage, leaving the grain practically unchanged.
Leather in its purest state
The aniline finish can be used on all types of leather – particularly on lamb and calfskins which are renowned for their fine grain -– and is applied by spraying the material with a transparent colouring solution which does not contain a pigment that will cover the grain. “The term ‘aniline finish’ comes from the colourants based on aniline that we used in the past. That product is now banned, but the terminology has remained,” explains Jean-Charles Duchêne of the Alric tannery. “The interest of an aniline finish is obvious: the skin is truly authentic, from a visual as well as a tactile point of view. The texture of pure aniline lamb leather is incomparably soft and the depth of colour is unique,” enthuses Patrick Couteau of the Bodin Joyeux tannery. “As well as the transparency and the feel of the leather, an aniline finish makes it easier to mould and shape the skin. In the past, it was widely used for leathers produced for binding. Now it represents only a small percentage of our production,” adds his colleague from the Jullien tannery, specialised in goat leather.
A leather for meticulous leather lovers
However, there are many drawbacks with this product. Starting with the skin’s defects, which are not hidden below a layer of pigment. “Using casein on box calf amplifies any defects, rather like looking at it under a magnifying glass,” adds an expert from the Annonay tannery. Given how rare these faultless first-choice skins have become, it is easy to appreciate the challenge for tanneries to offer aniline finished products able to satisfy the exacting requirements of the luxury houses. The second weakness is the fragility of the grain which is exposed almost without protection to all possible aggressions: scratches, stains, dirt, discoloration by light, not to mention the risk of the colour running when the article is rubbed. “That is the price to pay for absolute authenticity,” observes Patrick Couteau. The final drawback, and it is not a minor one when we think of the requirements of the luxury labels, is the irregularity of the colour. Drumming is used to add the colour, and as a result it can appear uneven over the same skin and vary from one skin to another. Without the use of an additional pigmented finish as well, the precision of the colour is too irregular. “For footwear, the colour variations and the problems of colour fastness are less of a problem as the assembled pieces are relatively small,” says Christian Bardes. “We can even out the colour with waxes that also offer a little bit of protection,” explains our contact from Annonay. “We can dye the leather twice, that helps to reinforce the colour,” adds Patrick Couteau. “Or add talc or a wax to enhance the shine,” concludes Jean-Charles Duchêne.
Pure aniline lamb leather from the Alric tannery
Pure aniline baby calf leather from the Alric tannery
Pure aniline lamb leather from the Bodin Joyeux tannery
Pure aniline goat leather from the Jullien tannery
Pure aniline calf leather from the Annonay tannery
Pure aniline calf leather from the Roux tannery
A compromise: semi-aniline
As we have seen, aniline leather as well as being very expensive as it is produced using very rare first-choice leathers, is also very delicate. Therefore, tanneries also offer a semi-aniline finish that includes a light pigmented coating. “Of around 30 to 50 grams of pigment per litre,” says Christian Bardes. “This provides unity and intensity of colour and a degree of protection for the skin”. “A semi-aniline finish allows us to correct the colour and add other properties such as resistance to scratches, light and rubbing. But it is still described as dipped lamb,” confirms Jean-Charles Duchêne. “Pure aniline leather is rarely used for leather goods as it is too sensitive to mechanical and chemical aggressions and is not colourfast. The preference is to use semi-aniline. 95% of leathers used to produce leather goods are pigmented,” says Christian Bardes.
Semi-aniline lamb leather from the Alric tannery
Pure semi-aniline baby calf leather from the Alric tannery
Pure and natural
Tanned using plant extracts, vegetable-tanned leather claims a greater degree of naturalness than chrome-tanned leather. Yet another reason for applying the lightest and most transparent finish possible, namely aniline, providing the skin presents none, or only the slightest, defects. “Our product entitled ‘vache végétale naturelle’ is a vegetable-tanned cow leather than has simply been nourished and dried, softened then sold as is…No colourants have been used for this article and its colour comes from the species of wood used to tan it,” explains Philippe Alfonsi from the Fortier Beaulieu tannery, specialised in vegetable-tanned leather. “We also offer a version that is coloured but without using any pigment, where the original aspect of the grain is unchanged.” The purest of the pure, in short!
Natural pure aniline vegetable-tanned cow leather from the Fortier Beaulieu tannery
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