Definition, History & Facts
Leather is defined as skins (smaller animals) or hides (bigger animals), that is preserved through tanning, which is a chemical treatment, that converts the perishable skin to a stable and nondecaying material.
Man has used leather for thousands of years, and leather is per definition a waste material or biproduct of food industry and has been always. The Egyptians and Hebrews developed vegetable tanning 400 BC, and leather tanning was widespread in Europe by the 15 century.
Finished leather has many uses, about half of all finished leathers worldwide are used for shoes, 10% on furniture, 15% on automotive, 5% on gloves, 10% on garments, and the last 10% on other leather products as leather goods.
Almost 70% of leather is bovine (cow or buffalo) and pig, sheep and goat is around 10% each.
These figures varies constantly, as they are under influence by demand for meat, and climate, agriculture and politics.
Tanning & types of Finishing
Raw hides can be up to 1 cm thick, so before tanning each hide is split into two layers, which we refer to as top grain leather and split leather.
Most of Sipos collection are top grain leather, as thinner leathers, which are more flexible and smoother are preferred for garments and upholstery.
Once the hide is split, the top grain leather can be used to make various types of leather. Basically, you can make full grain if the hide is beautiful and has less defects, or you can make corrected grain of the hide is lower quality. Corrected grain hides are lightly sanded or buffed to removed small defects, hereafter the corrected grain can be pigment with color, embossed with prints or left sanded as nubuck for a velvet look.
The hides which are beautiful enough to be left as full grain is used for Aniline or Semianiline. Aniline is the most prestigious, and aniline hides has no sanding, or coating of the grain. They are simply dyed through with a transparent dye, and maybe have a light finish in form of wax and oil. Semianiline is dyed the same way as aniline but has a protecting coating or pigment to cover some defects in the grain. Usually semianiline in good quality has a similar touch and feel as aniline.
Just to make things confusing, many refers to full grain as to leathers that has not been split, and still have the thickness and core of the leather intact, but full grain just mean that the grain of the leather has been left intact, and natural, during all tanning processes.
Aniline can usually be recognized by a nice warm touch and softness. Besides this the follicles can always be seen (through a magnifying glass or by zooming with the camera lens). Since aniline means natural and open surface, the follicles are seen open. Aniline is delicate and all stains will remain, and count as patina and be a part of the leathers history. Aniline are breathable and the most comfortable, both for garments and upholstery.
Semianiline can also have visible follicles, but they covered and closed. Touch and softness can be almost same as aniline, if it is done by a skilled tannery. Semianiline are more durable to use and still offers great comfort, but on upholstery and garment. Semianiline can be produced on corrected grain.
Pigment and corrected grain. Corrected grain is nubuck, and nubuck is as open as aniline. Only the best hides of corrected grain can be selected for nubuck. Most leather produced are corrected grain. A pigment is applied and grain-pattern is printed, leaving a very robust surface, which will last longer with greater stability. Stains from liquid and fat is seldom an issue with corrected and pigmented grain. Corrected and pigmented grain are not breakable.
Suede is upside down. Grain is left intact for securing the leathers strength, and fleshside is buffed to a velour. This is suede. If buffing/velour is made in the grain side, it is nubuck.
Suede for garments are made on skins with the grain intact, suede for shoes and bags are usually made of split leather.
Doubleface is leather or fur which can be used as reversible or without lining. Classic doubleface is lambskins with wool on, sheared (shearlings) and with back side made to suede or pigmented with finish or embossing. Many standard garment leathers are today finished with a light silicone on backside, not to make reversible, but to give opportunity to use without lining in garments or accessories.
Fancy leathers or Fantasy are leather with prints, embossing or coating, either to imitate exotic leathers, or to give a fashion effect.
Animal skins used for leather.
Cow leather can be up to 4-5 mm thick depending on the age and sex of the animal. Usually cow leather is sold in whole hides or sides (half hides), unless it’s heavy leathers for bags, shoes and belts. Depending on the use, it can be cut and sold as shoulder, croupons, double butts and more.
Cow leather can have anything from a very smooth to a very distinct grain, all depending on the natural character of the animal, and the skills of the tannery. Whole cow hides are usually between 45-65 squarefeet/hide (4-7 m2). Cow and calf leather very strong and durable.
Lamb leather can be up to 1,5-2,0 mm thick, depending on race and ages of the animal. Very thick lamb leather is difficult to find. Lamb are always sold in whole hides, and usually grain is very smooth and fine. Since lamb leather holds a lot of wool, the fiber structure in the leather is more loose, and therefore the leather is weaker compared to cow and goat. Special breeds of hair sheep offers same strength as goat and cow/calf.
Goat leather can be up to 1,5-2,0 mm thick, and are always sold in whole hides. Since goat has great strength it is popular for suede, but is also offered as grain leather. Grain is usually very distinct and recognizable.
Pig leather can be up to 1,0 mm thick. Thicker leathers can come from sows, but is a limited resource. Pig leather offers great strength and used for suede, and lining in shoes and bags. Pig leather is also popular for fantasy and fancy leathers, because of the low raw material price. Pig leather grain and split is always recognized by very visible follicles.
Many other leathers from more or less exotic species of animals are also offered.
Crocodile………….. just to name a few.
When choosing leather as fabric for your product, you have chosen exclusivity, durability, and made the right environmental and a sustainable choice.
Leather is not only in same category as cotton, wool, flax, bamboo, viscose and fur, it is also a bi-product of the food industry.
Your product, being a piece of garment, an accessory or a piece of furniture, most likely has its design or features from the leather chosen. Long pieces cut if cow or calf is used, density and lightness of lamb or goat suedes, or comfort and durability from upholstery cow hides, just to name a few.
All leather sold in Europe must comply to REACH which is the regulation of chemicals used in product in EU. Despite origin products always must comply to REACH (Regulation, Evaluation, Authorization and Restriction of Chemicals).
When choosing leather choice is often between Chrome tanning or Vegetable tanning.
Chromium tanning used to have a bad reputation, but thanks to REACH, it’s guaranteed that only harmless chromium III is used. Chrome tanned leather can cause allergy with a miner percentage of the consumer, but it is usually a problem, with skin contact under warm and humid conditions (imaging wearing shoes without socks in the summer). Usually problem is solved with using vegetable leather as lining inside the shoe.
Advantages of using chromium are many, most important are that chromium makes soft leather, tanning process is fast and highly effective, chromium tanning saves water and minimizes use of chemicals in later dyeing and finishing process. Tanning cow hides to wetblue facilitates global trade and processing.
Vegetable tanning has been marketed as an environmentally friendly alternative to chromium tanning. Vegetable tanning can be dated thousands of years back in time. Vegetable tanned leather is not as soft as chrometanned leather, and usage of water in tanning is noticeably big. Besides this vegetable tanned leather is time consuming, and when dyeing leather is usually retanned with chromium to stabilize colors.
Today tanneries with strong environmental profiles uses chrome tanning combined with very strict wastewater management.
Other types of tanning are mineral tanning, synthetic tanning (wetwhite) and chamois (oily tanning)