Glossary

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ALCA

American Leather Chemists Association, the professional body of leather scientists in USA.

Aniline Dyed

Leather that has been dyed by immersion in a dyebath and has not received any coating of pigmented finish.

Antique Grain

A surface pattern of markings or creases, usually irregular, in which the hollows are often given a contrasting colour to produce a two-tone or two-colour effect. The creases are produced by embossing,boarding or other similar means.

Antique Leather

Leather that has two dye layers, allowing one to be washed off or rubbed off (see rub-off and wash-off) to give an aged or antique look.

Automotive Leather

Leather that has been developed in accordance with CEN 289.

Aviation Leather

Leather that has been specifically treated to pass CAA regulations.

Bally Flexometer

A machine used to test the flexing endurance of leather in accordance with BS:6608.

Beam

A convex wooden slab sloping downwards from about waist height, over which a hide is placed for trimming off excess flesh and ragged edges and for unhairing by hand. Belly That part of the hide below the belly line. For steerhide leather, the belly line passes through a point at or above the top of the rear break. For cowhide leather, the belly line passes through a point at or above the top of the front break and a point not more than 2-1/2 inches below the top of the rear break. a - Part of the hide covering the underside and upper part of the legs of the animal. b - Leather made from (a).

BLC Leather Technology Centre

A privately owned research organisation based in Northampton, that provides a consultancy service in all aspects of leather and its production.

Bleeding

The transfer of materials exuded from leather to other material that comes into contact with it. It is usually designated as staining.

Boardy

Adjective applied to stiff, inflexible leather.

Break

The superficial wrinkling formed when the leather is bent, grain inward, with a radius of curvature like that formed at the vamp of a shoe in walking. Adjectives commonly used to describe this characteristic are tight, loose, coarse, and pipey (see pipeyness).

BS 3144

The superficial wrinkling formed when the leather is bent, grain inward, with a radius of curvature like that formed at the vamp of a shoe in walking. Adjectives commonly used to describe this characteristic are tight, loose, coarse, and pipey (see pipeyness).

BS 6608

This is the former British Standard for cattle hide leathers for upholstered furniture, it is now obsolete and has been replaced by BSEN 13336. It gives guidelines as to the physical specification of leather, e.g. rub fastness, flexing endurance.

BS 7176

This is the British Standard Specification for resistance to ignition of upholstered furniture for non-domestic seating [assessed] by testing composites.

BS-EN 1021-1

Is the test method for assessment of the ignitability of upholstered furniture, with the ignition source being a smouldering cigarette.

BS-EN 1021-2

Is the test method for assessment of the ignitability of upholstered furniture, with the ignition source being a match flame equivalent.

BSEN 13336

The current standard for upholstery leather in Europe.

Buffed Leather

Leather manufactured by removing minor blemishes from the grain layer by an abrasive or bladed cylinder or, less generally by hand. In the case of upholstery leather the buffing process is invariably carried out by machine though it is sometimes incorrectly described as "hand buffed".

Buff Leather

White or cream coloured, flexible, dry feeling, oil tanned cattle hide leather with a velvet-like nap on the grain side.

Butcher Cuts

Damage to hides caused by improper removal of flesh / detritus from the animal. Damage is usually in the form of cuts or furrows on the flesh side, sometimes called flay damage.

Butt

The part of the hide after the bellies and shoulders have been removed.

CAA

Civil Aviation Authority - the regulatory body for aviation in UK.

Chrome Tanned

Leather tanned either solely with chromium salts or with chromium salts together with quite small amounts of some other tanning agent used merely to assist the chrome tanning process, and not in sufficient amount to alter the essential chrome tanned character of the leather.

Chromium (III)

The most popular mineral used in the tanning process, used because of its excellent high shrinkage temperature and lightfastness properties.

Chromium (VI

This is the oxidised form of Chromium (III) and is classified as a human carcinogen. This mineral salt is not used in the tanning of leather.

Cigarette & Match Test

Test that forms part of BS 7176, the resistance to ignition of upholstered furniture. This particular section deals with the resistance to ignition of leather to a smoldering cigarette and simulated match.

Coated Leather

Any leather which has a surface coating in excess of 0.15mm and the thickness of this coating is less than 1/3 of the total thickness of the product.

Collagen

The principal fibrous protein in the corium or derma layer of a hide or skin.

Conditioning

The process where the temperature and humidity are regulated prior to testing. The requirements are that the temperature must be 23oC plus or minus 2oC and 50% Relative Humidity, plus or minus 5%. These are set in accordance with BS 3144.

Corium

The term given to the main component of the hide fibre structure (see figure 2).

Corrected Grain Leather

Leather from which the grain layer has been partially removed by buffing to a depth governed by the condition of the raw material and upon which a new surface has been built by various finishes.

Crib

An open structure wooden crate, whose size determines the nature of various iginition sources, for testing differing degrees of fire retardency.

Crib 5

The term given to a composite flammability test, often involving leather or other surface materials. A crib (see above) of size “5” is used in BS5852:2006 and leather that passes this test is often referred to as “crib5” leather.

Crosslinker

A chemical agent that reacts and crosslinks across the top layer of finish to give enhanced rub-fastness properties to the finish.

Crust

Sometimes used as an adjectival noun, “in the crust”, to describe leather that has been dyed and dried, but not finished.

Curing (Finishing)

The period when the crosslinking reaction in the finish is taking place, a curing reaction proceeds with time and more rapidly with heat. It can be hindered by low temperatures and a humid atmosphere.

EASA

European Aviation Safety Agency - the regulatory body for aviation in Europe.

Embossed

Raised pattern either imitating the pattern of some animal, or giving a different pattern to the grain, quite unrelated to a natural grain pattern.

Leather Embossed

Leather embossed or printed with a 3-dimensional pattern either imitating or resembling the grain pattern of some animal, or unrelated to a natural grain pattern.

FAA

Federal Avition Authority - the regulatory body for aviation in USA.

Fatliquor

A modified oil or grease, usually formulated with an emulsifying agent to form an emulsion of oil in water, used to lubricate the fibres of the leather to impart a soft feel to the leather.

Finish

The final surface coating of the leather. - The surface coating applied to a leather. - The final process or processes in the manufacture of dressed leather. - The final appearance of the leather, e.g bright, matt and velvet.

Finishing

The final process or processes in the manufacture of dressed leather.

FIRA

Furniture Industry Research Association.

Flaying

Damage to hides caused by improper removal of flesh / detritus from the animal. Damage is usually in the form of cuts or furrows on the flesh side, sometimes called flay damage.

Flexing Endurance

A measure of how the finish of a piece of leather will behave over time, with respect to the surface layer cracking.

Full Grain

Leather bearing the original grain surface of the skin and with none of the surface removed by buffing or splitting. In contrast see "corrected grain". Leather bearing the original grain surface as exposed by removal of the epidermis and with none of the surface removed by buffing, snuffing or splitting.

Goad Marks

Small pit marks on the grain layer, caused by farmers prodding the animal with a metal tipped goad, pitchfork or similar implement.

Grain

The outer or hair side of a hide or skin, which is the pattern characterized by the pores that are peculiar to the animal concerned. They are visible on the outer surface of a hide or skin after the hair or wool and epidermal tissue have been removed. Also used as an adjective referring to that side.

Grain-Corium Junction

The boundary of the grain and corium layers. The breakdown of this layer is one of the principal causes of looseness.

Grey Scale

A measure for assessing the change in colour in scales of grey. Used in the leather industry to determine the colour change when examining colour transference in rub-fastness testing.

Growth Marks

Rippling of the hide, usually found around the neck area, that are due to animal’s growth pattern. Associated marking on the hide or leather can be accentuated by the liming process.

Grub Hole

A hole through the hide caused by the penetration of the grub of the warble fly.

Handle

A word used to describe the feel, softness and texture of a piece of leather.

Hand Wash

A type of leather, where the pigment effect is made entirely by hand, ensuring each hide is unique.

Heat Release

An aviation composite test that measures the specific energy output of the composite as it is exposed to a flame source. The energy output is measured in KiloWatts and is typically needed for wall panels and interior components on commercial jetliners globally.

Hide

The pelt of a large animal, such as cow, horse, etc. Also sometimes used interchangeably with ‘skin’. The outer covering of a mature or fully grown large mammal e.g cattle, horse, camel, elephant and whale. Leather made from (a) that has not been split, or from the grain split of such hide.

IULTCS

International Union of Leather Technologist & Chemists Societies, an umbrella organisation for the different leather technologist societies around the world.

Leather

Hide or skin which still retains its original fibrous structure more or less intact, and which has been treated so as to be imputrescible even after exposure to water. The hair or wool may or may not have been removed. Certain skins, similarly treated or dressed, and without the hair removed, are termed "fur".

Leather Studs

To add further value for our customers, the supply chain can be organised to deliver leather as cut parts. Automated cutting makes the optimum use of the natural shape of a hide, producing the maximum number of components with minimum waste - and all at a fixed price. The latest laser-guided technology lets us cut with precision and allows for a just-in-time supply of leather parts. Deliveries can be made by grouping pre-cut parts together by project to ensure that clients are never short of leather. There's no need to maintain a minimum stock-holding - a key benefit for our clients' cash flow.

Looseness

A term given to leather where: - The grain corium junction has broken down and the result is that the boundary has become very loosely joined. - The grain layer has been allowed to relax, to emphasise that its area is bigger than the corium. - Too much substance is removed from the corium during chemical processing early in the process of making the leather Looseness gives an appearance of large wrinkles when it is distorted, the leather feels empty and almost bubbly.

Mange

Mites that penetrate into the corium layer and encyst themselves as the fibres grow around them The contents of the cysts dissolve during the beamhouse processing and small depressions in the grain layer are the result.

Mineral Tanned

Leather that has been tanned with mineral salts such as aluminium(III), chromium(III) or zirconium(IV) salts.

NAMAS

The former name of UKAS, the government accreditation organisation.

Nappa

Soft full grain gloving or clothing leather made from unsplit sheep or lambskin or kid-skin. It is usually tanned with alum and chromium salts and dyed throughout its substance. Soft full grain leather, formerly made from unsplit sheepskin or lambskin or kidskin for gloving or clothing, but nowadays also made from split hide. It was originally tanned with chromium salts and dyed throughout its substance. Originally made in the town of Napa, California, from whence it derives its name.

Natural Defect

Defects in the hide or skin that occur naturally throughout the life cycle of the cow, examples include scars, scratches and growth marks.

Nubuck

Cattle hide leather buffed on the grain side to give a velvety surface that has a distinctive nap to its surface.

Raw Hide

A hide which has only been treated to preserve it prior to tanning.

Retannage

A modifying secondary tannage applied after intermediate operations following the primary tannage, either to even out the primary tannage or impart different properties to the leather.

Retanned

Leather which has been subjected to an additional tannage after primary tannage, with similar or other tanning materials.

Rub-Fastness

If something has a fastness to something, then it will not change its properties in its presence, e.g. something that is fast to rubbing or has good rub fastness, will not change colour easily when rubbed. The resistance of a leather to the rubbing effect of a felt pad, either wet or dry, to simulate wear in use.

Rub-Off

A type of leather with a fugitive top coat that, once treated with the appropriate chemicals, moves and creates an antique effect. This effect must then be sealed with a lacquer to stop any further movement.

Russet

A type of leather with a fugitive top coat that, once treated with the appropriate chemicals, moves and creates an antique effect. This effect must then be sealed with a lacquer to stop any further movement.

Sammin

A piece of leather is sammed after it has passed through a samming machine. This is a machine that reduces moisture in leather in a similar way to a high pressure mangle.

SATRA

Shoe & Allied Trade Research Association, a testing house that started out solely with the shoe leather industry, but now covers all sectors of the leather industry and many other industry sectors.

Sauvage

A very soft aniline type leather that is dyed using a similar process to tie-dyeing, the effect means that the colour is always different.

Shank

Leg portion of hide pattern.

Shoulder

The fore part of the hide, cut off at right angles to the back bone, with the belly cut off and the head cut off behind the horns.

Side

A side is half a hide cut along the back bone line.

Skin

The outer covering of small animals and other vertebrates, e.g. sheep and goats or of the immature animals of the larger species, e.g. calves and colts or of reptiles.

SLTC

Society of Leather Technologists & Chemists, a society that is the technical and professional body of all leather scientists.

Solvent-Based Finish

A finish that is delivered to the substrate with a non aqueous solvent as the medium.

Spec8

Specification 8, is the old name for FAR/JAR 25.853 with respect to flame resistance testing for aircraft interior materials. It is adopted from FAR 25.853 and FAR 25.855, which is the specification set by the United States Federal Aviation Authority.

Spectrophotometer

A device that measures the spectral absorption of an object, i.e. the colour. It has many advantages over a colorimeter, mainly that it is more accurate and colorimeters cannot detect metamerism.

Split

A single layer from a hide or skin that has been separated over its whole area into two or more layers. The layers thus obtained are termed: (a) grain split (outer split); (b) flesh split (inner split).

Splitting

The process of cutting leather into two or more layers.

Spue

Spueing is the term given when a component of the leather migrates to the surface. The two most common types are fatty spues and salt spues. Fatty spue looks like white fluffy clouds on the surface of the leather and disappears with localised heating because it is due to low melting point fatty acids. Salt spue can be removed with a damp cloth

Staking

A process where finished leather is subjected to a pummelling type of mechanical stressing by a machine, to soften it.

Stucco

A polymer that is used to fill small cuts and scars. It comes in a putty type form that, when allowed to air dry, forms a dry but flexible filling.

Substance

The measure of the thickness of the leather.

Tannage

A product that has bonded with the fibres of a skin or hide to modify the properties of the collagen, to provide resistance to microorganisms, so that it will not putrefy.

Tannery Run

Used to describe leather that has not been sorted and graded before selling by the tanner.

Tanning

Processing whereby putrescible raw hides and skins are converted into leather.

Tick

A tick is a mite, that attacks an animal, by piercing the skin with its long proboscis and sucking blood. The marks that it leaves are like many pin pricks in the grain and scars.

UKAS

United Kingdom Accreditation Service, a government body that accredits companies and organisations to ensure they follow whatever standard they claim to use. Most well know for accrediting laboratories and ISO 9000 assessment bodies.

Upper Leather

Leather produced for the outside upper part of footwear.

Vegetable Tanned

Vegetable tannins are plant polyphenols, which may be supplied as an extract of part of a plant eg the bark of trees or they may be supplied as powdered plant parts eg seed pods. Vegetable leather is tanned exclusively with vegetable tanning agents, or with such materials together with small amount of other agents used merely to assist the tanning process or to improve or modify the leather.

Veiny

Veins can show up on the flesh side of leather as branch marks. The cause is inadequate bleeding after the animal is killed or the selective degradation of the vein material by elastolytic enzymes, during the earlier stages of processing. The areas that used to contain a vein can become very loose, the leather is then said to be veiny. In extreme cases, the veins can show up in the grain layer.

Veslic Rub-Fastness Tester

A machine used to determine the rub-fastness of a piece of leather.

Warble Fly

A warble fly causes damage to skin, by laying eggs in the hair or on the legs of cattle. The larvae then burrow into the flesh of the animal and live and grow inside the animal. After some months, the larvae create breathing holes through the skin, usually seen in the middle of the back, towards the neck.

Wash-Off

Leather that has two dye layers, allowing one to be washed off or rubbed off (see rub-off and wash-off) to give an aged or antique look.

Water-Based Finish

A finish that is deposited on the substrate with water as the solvent medium.

Wet-Blue Leather

Leather which has been chrome tanned, but has not been further processed and is sold in the wet condition.

Wrinkle

A permanent crease or furrow on the grain surface of a hide or leather, incapable of removal by rolling or plating.