Leather and its origin
The leather industry is one of mankind’s oldest. Our most distant ancestors used skins to protect their body, hands and feed. Leather can be created from the hide of any mammal, reptile, bird or fish thanks to a procedure called tanning. This procedure preserves the skin, without which it would soon rot.
Today, at least half of the leather produced is transformed into shoes, and around a quarter into clothing. Only around 15% is used for furniture, while the rest is transformed into leatherwear and other consumer goods.
Thanks to its durability and comfort, leather has always been used to cover furniture or means of transport. The first leathers were made from cow skin, calfskin, pigskin, fowl and goats. Skins come from animals which have been hunted or bred for food. Current trends mean that most furniture leather comes from cow hide, given that this is easily available and easily adaptable to the needs of today's designers, manufacturers and customers.
Far from losing its popularity, today leather is the material of choice for many - not only for furniture, whether commercial or private, but also in the automobile and aviation industry and the nautical sector.
The natural characteristics of leather
Real leather is a natural product. It breathes, it’s warm and boats characteristics which make each hide unique. Leather will always bear the marks of its natural origin and these characteristics can manifest themselves in the form of scars, stretch marks, areas of dense fibres or uneven pore structure. These marks in no way compromise the quality of the leather, but are rather signs appreciated by well informed purchasers when they buy leather. With time and use, leather develops a patina which underlines its beauty.
Veins and stretch marks
These are indications of the age of the animal, and as such they are like the grain on a piece of wood. They may range from an extremely pronounced mark in the neck area to very subtle strips across the skin perpendicular to the backbone. The most pronounced stretch marks are often placed on the rear of seat backs.
These are generally formed as the result of contact with barbed wire or the horns of another animal. When these marks turn into scar tissue the new layer of skin is as solid as the rest of the skin, but when they do not turn into scar tissue they should be rejected, as stress on this part of the skin risks causing a tear.
Variations in the grain of the skin
The texture of the fibre can vary greatly, from being slack in the stomach area to more tense in the dorsal column area. The slackest areas therefore have more give.
Variations in pore structures are particularly visible in natural grain leather, where it is often possible to observe groups of dilated pores.
Each hide is unique, and because of the different grains mentioned above dyes and finishes penetrate differently into each part of the skin, given elegant nuances. While we seek to maintain a uniform look, this is not always possible or indeed desirable.
The different tanning processes
In this process hides are treated with vegetable tannins extracted from the bark and wood of certain trees. Over centuries, oak bark has been used as a source of tannin, but today, mimosa tannin, extracted from the bark of different varieties of mimosa, is more common. Vegetable tanning is traditionally carried out in pits: hides are suspended in a series of pits or tanks filled with a tanning solution which becomes stronger day after day. This process is slow and can take several weeks, indeed several months, before the hides are fully tanned. Today this method is rarely used in the production of furniture leather. More modern scientifically controlled processes are employed, using tanning agents in the latest stages of the process to speed it up.
This tanning is generally carried out with the use of basic chromium sulphate, a mineral salt which penetrates rapidly into the skin, the tanning process thus being completed in twenty four hours. In this case the leather is a light/ pale leather rag, which after the appropriate treatment becomes a modern high quality and supple leather. Other mineral tanning agents (e.g.: alum) are also used.
Hides are now in the last stage of production. A fulling process enables the addition of dyes, chemical fungicides, a re-tanning agent and fatty liquors which give the finished product a supple feel, as well as, if necessary, fireproofing products.
Hides are firstly dried by wringing the excess water out in a large wringer or blower, and by stretching skins on a frame which is then passed through a drier.
The different types of finishes
Pigmentation and veneering
Pigments are applied to the surface of finished hides. They are added by roller or a combination for the first application, and using a spray for subsequent pigment layers. A final layer of veneer is applied in order to give the finish a protective film against wear and dirt.
Sometimes a grain is “printed” onto the surface of the leather. This creates a more uniform break (the natural aspect which appears on the folds of the skin) and makes it possible to camouflage scars and marks.
Hides are placed in large stainless steel drums. During this process the natural fibres relax, and suppleness to the touch (the handle) is created.
Full grain leather
is a leather which has preserved its original surface: the grain. The finest part of the leather, this shows the characteristics of the skin: natural grains and wrinkles.
is a “full grain” leather which has been dyed in an aniline fuller on which the transparent finish is created by an extremely fine protective film which gives the hide softness and suppleness.
Corrected grain leather
is a leather which has undergone a mild sanding of the grain with the aim of creating a homogenous surface and getting rid of some overly pronounced marks.
is a full grain or corrected grain leather on which an opaque finish gives a more regular surface and greater durability.