HAND-CRAFTED LEATHER GOODS
Descriptive terms used in connection with leather - continued
Skived leather:- This is reducing the thickness of your leather to make joins, overlaps or folds, less bulky, or any other situation requiring the leather to be thinned. It is invariably done on the flesh side. Though one exception would be joining thong (or lace), with an adhesive, as obviously the finished side would have to be skived as well to ensure the thong (or lace), was of a consistent thickness.
Snuffing:- The process of lightly buffing the grain surface of the leather by the use of a fine abrasive. Snuffing leaves some of the surface imperfections still visible; buffing removes them entirely.
Splits:- Thick leather may be split
into two or more layers before tanning. The top, or grain layer, is known as the
grain split or top split. Consequently, the underlying layers are middle and
flesh splits. Grain splits may be finished on the grain or the flesh side.
Middle or flesh splits are sueded on both sides. A suede split is sueded on both
sides, though one side may be fuzzier than the other. Any type of skin or hide
that has not been split or shaved is described as full. Bear in mind that split
cowhide, for example, is not the same as cowhide split. Using split as an
adjective, as in split cowhide, means a grain split. Using it as a noun, in
cowhide split, it means a middle or flesh split.
Steer:- The hide of a freshly killed bull, castrated at a young age and having a mass of more than 17 kilograms.
Stingray:- In Japanese it is referred to as Honzame, in Europe as Shagreen. In France, it is known as Galuchat, named for Jean-Claude Galuchat, an 18th century master leatherworker for Louis XV and the first French artisan to use the material. Related to sharks, Stingray will not burn, break or fray, yet it can be cut with a standard pair of scissors. In Egypt when the tombs of ancient pharaohs were discovered, stingray was found to have been used as armour, decoration and ornamental embellishment.
According to CITES (The Convention on International Trade in Endangered Species of Wild Flora and Fauna) which have three documents known as the CITES Appendices — Appendix I (507 named taxa), Appendix II (259 named taxa) and Appendix III — Stingray is not included in these appendices and therefore legal for commercial use and trading throughout the world.
The Cowtail stingray (Trygon sephect) and the Spotted stingray (Trygon kuhtii) are caught by traditional fisherman for meat, and the skins were previously discarded. Both species are neither endangered nor threatened. They are abundantly found in the shallow and muddy warm waters off Indonesia.
In the old days, the skin was normally used by wood-craftsmen as a sander, because of its rough surface. Creating markets for stingray skin products has increased the income of traditional fisherman families in Java. People finally caught on that the naturally shiny beading, amazing strength and the unique stingray pearl pattern are perfect qualities for some of the finest leather products available in the world today.
Stingray leather is processed from rays caught off the north coast of Java. The
skin has a beautiful appearance and sturdy durability because the microscopic
fibres of the stingray leather are woven together, unlike ordinary cowhide,
which has parallel fibres.
Until recently, attempts at tanning stingray leather failed, considering the fibre structure of marine leather, and the result was a stiff, fragile product, but this has now been overcome.
Struck through:- The dyeing of leather can be controlled by the manufacturer to either fully or partially penetrate it. Since full penetration requires more dye, leather that has been fully penetrated is, therefore, more costly to produce than leather that has only been superficially (the flesh and grain surfaces) penetrated. Leather that has been fully penetrated with dye is known as fully struck through leather. If it has only been superficially dyed, it is called partially struck through.
Suede leather:- Suede is not another kind of leather at all, but a type of finish. All suede is leather, but not all leather is suede. The term "suede" refers to a type of finish originally applied to leather produced in Sweden which had had the grain layer (the outer surface of a hide or skin after hair/wool removal) removed and a fine nap raised by mechanical action. Although normally today suede is made from either the original flesh surface of a hide/skin, or one exposed by splitting laterally the hide or skin into two layers, the grain surface is sometimes abraded to give a very fine suede effect usually called nubuck, but sometimes referred to as degrained leather. It is only leather that is finished by buffing the flesh side to produce a nap. It is unrelated to the type of hide or skin that is used.
Light purple - corrected grain
Orange coloured suede
Black - full grain calfskin
Tawed leather:- The tawing method of making leather is a very ancient one. It was used in ancient Egypt, Assyria and Babylon and India. The Greeks and Romans used tawing and it was widely employed during the Middle Ages in Europe. In tawing, the skins are first soaked in water to soften them, then the skin and hair are scraped off with a concave "scudding knife". Tawing is a mineral process using alum and salt (the best mixtures contain alum, salt, egg yolk, flour and oil) and originally produced a white leather, though later it was dyed in colours (and most prized was the scarlet leather dyed with kermes). The leather is hung up to dry, dampened again (fermented bran can be used to make the highest quality leathers) and then beaten with mallets to soften it, before being staked out ready for use. After the Moorish conquest of Spain in the eighth century in Cordova a process of tawing leather was practised which was made from the mouflon sheep.
Temper:- Defines the pliability/softness of the leather.
FIRM: Leather that has hard and bony characteristics. Firm leather represents products requiring very little flexibility.
REGULAR: Leather is slightly firm and having no bony qualities. When worked, regular leathers display smooth, even folds.
MELLOW: This type of leather is very limber and pliant. No snap when worked, tends to lack firmness.
SOFT: Leather that is extremely flexible and pliant.
Top grain:- This description is intended to define genuine grain leather as opposed to leather which has been pigmented and embossed with a grain finish that is entirely new.
Unfinished leather:- Is usually the description applied to an aniline-dyed leather with unaltered, natural characteristics.
Upholstery leather:- This is leather processed for use in the furniture trade, for use in motor vehicles or aeroplanes. (Though for aircraft the leather must first be treated to make it flame resistant.) Chrome or vegetable-tanned split. Firmer than garment cowhide. Various finishes and imitation grains.
The physical properties which make leather a unique and valuable material for upholstery purposes are:
* High tensile strength
* Resistance to tear
* High resistance to flexing
* High resistance to puncture
* Good heat insulation. Leather contains a great deal of air, which is a poor conductor of heat. This is an important comfort consideration.
* Permeability to water vapour. Leather fibres will hold large quantities of water vapour. This property enables leather to absorb perspiration, which is later dissipated. A significant factor for comfort.
* Thermostatic properties. Leather is warm in winter and cool in summer.
* Mouldability. Leather can be moulded and will retain its new shape. It has both elastic and plastic properties in wear.
* Resistance to wet and dry abrasion. These properties, concerned with wear and maintenance, are controlled by the tannage and surface finish. These have now reached high levels of excellence.
* Resistance to fire. Leather is inherently resistant to heat and flame.
* Resistance to fungi. Leather is resistant to mildew.
* Resistance to chemical attack. The atmosphere of modern cities is polluted from the burning of carbon fuels with sulphur dioxide gas, which can accelerate the deterioration of leather. Modern leathers are tanned and dressed to resist these harmful chemicals.
Vellum:- This is un-split calfskin manufactured into an opaque material with a smooth surface, in the same manner as parchment.
Dirty Jobs - Making vellum
Velours:- Chrome-tanned leather with a polished grain or flesh side. Velour products are made of tanned semi-finished leather with serious grain defects unsuitable for products with a natural outer surface. Used primarily for footwear uppers, clothes and fancy leather goods.
Velvet leather:- Leather with the grain surface abraded to a fine nap or velvet-like finish in contrast to the flesh side abrading of suede.