Saturday, November 17, 2007

Leather Types

In general, leather is sold in three forms:

  • Full-Grain leather, made from the finest raw material, are clean natural hides which have not been sanded to remove imperfections. Only the hair has been removed. The grain remains in its natural state which will allow the best fiber strength, resulting in greater durability. The natural grain also has natural breathability, resulting in greater comfort for clothing. The natural Full-Grain surface will wear better than other leather. Rather than wearing out, it will develop a natural "Patina" and grow more beautiful over time. The finest leather furniture and footwear are made from Full-Grain leather. Full grain leathers can mainly be bought as two finish types: aniline and semi-aniline.
  • Corrected-Grain leather, also known as Top-Grain leather, is fuzzy on one side and smooth on the other. The smooth side is the side where the hair and natural grain used to be. The hides, which are made from inferior quality raw materials, have all of the natural grain sanded off and an artificial grain applied. Top grain leather generally must be heavily painted to cover up the sanding and stamping operation. Corrected grain leathers can mainly be bought as two finish types: semi-aniline and pigmented.
  • Suede is leather that has had the grain completely removed or is an interior split of the hide/skin. During the splitting operation the grain and drop split are separated. The drop split can be further split (thickness allowing) into a middle split or a flesh split. In very thick hides the middle split can be separated into multiple layers until the thickness prevents further splitting. The strongest suedes are usually made from grain splits (that have the grain completely removed) or from the flesh split that has been shaved to the correct thickness. Suede is "fuzzy" on both sides. Suede is less durable than top-grain. Suede is cheaper because many pieces of suede can be split from a single thickness of hide, whereas only one piece of top-grain can be made. However, manufacturers use a variety of techniques to make suede appear to be full-grain. For example, in one operation, glue is mixed with one side of the suede, which is then pressed through rollers; these flatten and even out one side of the material, giving it the smooth appearance of full-grain. Latigo is one of the trade names for this product. A reversed suede is a grained leather that has been designed into the leather article with the grain facing away from the visible surface. It is not a true form of suede.

Other less-common leathers include:

  • Buckskin or brained leather is a tanning process that uses animal brains or other fatty materials to alter the leather. The resulting supple, suede-like hide is usually smoked heavily to prevent it from rotting.
  • Patent leather is leather that has been given a high gloss finish. The original process was developed in Newark, New Jersey by inventor Seth Boyden in 1818. Patent leather usually has a plastic coating.
  • Shagreen is also known as Stingray skin/leather. Applications used in furniture production date as far back as the art deco period. The word "Shagreen" originates from France and is commonly confused with a shark skin and stingray skin combination.
  • Vachetta leather is used in the trimmings of luggage and handbag, popularized by Louise Vuitton. The leather is left untreated and is therefore susceptible to water and stains. Sunlight will cause the natural leather to darken in shade, called a patina.
  • Slink is leather made from the skin of unborn calves. It is particularly soft, and is valued for use in making gloves.
  • Deer Skin - This is probably the toughest leather in the world, given that most wild deer are constantly getting in and out of thorny thickets in the forests. Deerskin has always been prized across societies - notably the North American Indians who used to treat it with lime and other compounds to make the raw deer hide more supple, often "staking" it out in different weather conditions etc. Modern deer skin is no longer procured from the Wild as it were, with "deer farms" breeding the animals specifically for the purpose of their skins. Such farmed deer skins are usually procured from New Zealand and Australia in today's times. Deer Skin is prized for use in Jackets and Overcoats as well as high quality personal accessories like handbags and wallets. It commands a high price owing to its relative rarity as well as its proven durability.
  • Nubuck is top-grain cattle hide leather that has been sanded or buffed on the grain side, or outside, to give a slight nap of short protein fibers, producing a velvet-like surface.

There are two other descriptions of leather commonly used in specialty products, such as briefcases, wallets, and luggage.

  • Belting leather is a full grain leather that was originally used in driving pulley belts and other machinery. It is often found on the surface of briefcases, portfolios, and wallets, and can be identified by its thick, firm feel and smooth finish. Belting leather is the only kind of leather used in luxury products that can retain its shape without the need for a separate frame; it is generally a heavy-weight of full-grain, vegetable-tanned leather.
  • Nappa leather, or Napa leather, is extremely soft and supple and is commonly found in higher quality wallets, toiletry kits, and other personal leather goods.

The following are not 'true' leathers, but contain leather material.

  • Bonded leather , or "Reconstituted Leather", is not really a true leather but a man-made material composed of 90% to 100% leather fibers (often scrap from leather tanneries or leather workshops) bonded together with latex binders to create a look and feel similar to that of genuine leather at a fraction of the cost. Bonded leather is not as durable as other leathers, and is recommended for use only if the product will be used infrequently. One example of bonded leather use is in Bible covers.
  • Bicast leather is a man-made product that consists of a thick layer of polyurethane applied to a substrate of low-grade or reconstituted leather. Most of the strength of bicast leather comes from the polyurethane coating, which allows this material to be used where strength or durability are required.

The vast majority of leather is sold according to its area. The leather is placed through pin-wheel or electronic measuring machines and its surface area is determined. The unit of measurement is square metre, square decimetre or square foot. The thickness is also important, and this is measured using a thickness gauge (the unit of measurement is millimetres, e.g., 1.8 mm is a standard thickness for a school shoe).

In some parts of the world top-grain thicknesses are described using weight units of ounces. Although the statement is in ounces only, it is an abbreviation of ounces per square foot. The thickness value can be obtained by the conversion:

  • 1 oz/ft² = 1/64 inch (0.4 mm)

Hence, leather described as 7 to 8 oz is 7/64 to 8/64 inches (2.8 to 3.2 mm) thick. The weight is usually given as a range because the inherent variability of the material makes ensuring a precise thickness very difficult. Other leather manufacturers state the thickness directly in millimetres. (source Wikipedia)

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