Back (leather)

Leather made from the main portion of hide, obtained by cutting off the two bellies.

Back (of animal)

Main portion of hide, obtained by cutting off the two bellies.
Note: In North America a back is a half cattle hide (or side) after the removal of the head and belly.

Bacteria

Bacteria are the smallest organisms that can complete their life cycle independently. They lack a nucleus and membrane-bound organelles. They may be autotrophic or hetrotrophic and occur in a wide range of environments. They are abundant on the remains of dead plants and animals and some cause disease in other living organisms. Bacteria are also responsible for such process as fermentation and decomposition.

Bacterial damage

Hides and skins damaged and rendered evil-smelling by bacterial damage. See: Putrefaction.

Bactericide

Agent or treatment that specifically kills bacteria.

Bag tannage

Mode of tannage, formerly used for Morocco leather, in which the prepared skins are sewn into bags, grain outwards, filled with a slurry of sumac and some air, tied at the opening, floated in a sumac liquor for a period and finally removed and piled upon each other to force the liquor through the skin.

Bagginess

Development of a pouched or bag-like area in leather owing to excessive plastic stretching of the leather.

Bagging test

Test to evaluate the deformation of the leather. For example, in the area of a garment or armchair where the leather is subjected to a stretching without restoring the original form.

Bale

Closely pressed package of goods, such as hides or skins, bound together with cord, wire, plastic hoop, etc., ready for storage or transportation.

Balling up

Forming of small balls when a resin finish is applied by padding or brushing. Usually caused by the presence of buffing dust or to poor mechanical shear of the resin. See: Pilling.

Band

1. Strip of material, such as leather, used to seal junction parts of machines or apparatus.

2. More or less wide zone of a spectrum absorbed or emitted by a material.

Band damage

Caused by metal band used to bale up raw skins for transport.

Bandknife

Long, flexible, continuous knife of a splitting machine.

Barbed wire

Wire to which sharp, protruding, wire points are fixed at intervals. Mostly used around an enclosure.

Bark-tan (v); bark tanning

Tannage based mainly upon the tannins contained in the bark of trees, the leather in process coming in contact with the raw bark.

Base coat

Depending on the type of leather the base coat provides the first coat for all subsequent finishes and top coats. Its purposes are

      correction of the varying absorbing capacities in the different sections of the hide, levelling and filling effect and improvement of adhesion between the leather surface and all following coats.

Base dyeing

Dyeing of a leather to a suitable colour before the final dyeing or the application of a pigmented finish.

See: Sandwich dyeing.

Base lacquer

First of the lacquer coats applied in the manufacture of patent leather.

Basement membrane

Continuous thin film of specialised extracellular material which physically separates cells from the surrounding connective tissue.

Basic chromium sulphate

Salt obtained by treating normal chromium sulphate Cr₂(SO₄)₃, in the form of chrome alum, with an alkaline substance such as sodium carbonate, or by treating a suitable mixture of dichromate and sulphuric acid with an organic substance, such as glucose. The compositions of 33% and 66% basic salts can be represented as Cr₂ (OH) ₂ (SO₄) ₂ and  Cr₂ (OH) ₄SO₄. Used in chrome tanning.

Basic dyestuff

Dyestuff with a dyeing cation, often pasted with acetic acid to assist dissolution.

Basicity

Relationship between chromium atoms and the acid radicals (or the basic hydroxyl groups) in a chromium compound. Usually it is expressed as the percentage ratio between the number of chromium atoms and the maximum number of -OH which is possible to associate with them in a compound varying from 0% in the chrome sulphate to 100% in the chrome hydroxide Cr(OH)_3. (Basicity percentage or Schorlemmer).

Basification

Process of rendering a chrome liquor, or other mineral tanning agent, more basic, either before use or during tannage, by addition of a solution of an alkaline substance (sodium bicarbonate or carbonate).

Basify (v); basifying

To increase the pH of a chromium tanning bath or salt to increase the basicity.

Basil

Unsplit pelt, usually of a woolled sheepskin, vegetable tanned. Note: In the UK, this leather is sometimes called "full sheep".

In Germany the term is not applied to rough tanned sheep leather, but is also used as a description of origin in the case of the woolled sheepskin.

BAT

See: Best Available Technique.

Batch

Number of items forming a group or dealt with together; using or dealt with in batches, not as a continuous flow.

Bate

Natural material, or a synthetic mixture, which by microbiological and/or enzymatic action dissolves and/or modifies certain protein components of the skin.

Bate (v); bating

To treat unhaired and limed pelt with a bate.

Bath

Liquor in which a treatment is given or a vessel for such a liquor.

Beam

Convex structure, fixed at an angle to the ground, over which suitably prepared hides or skins are placed for unhairing, fleshing or scudding.

Beamhouse

Section of the tannery where hides or skins are prepared for tanning, which includes the operations of soaking, unhairing, fleshing and deliming etc.

Beating

Process of removing loose salt and foreign matter from a salted hide prior to weighing by beating, banging or shaking it in an  agreed manner.

Note: By beating the hair and flesh sides once on the ground, or by banging it against a “horse” or “buck” or pack of hides.

See: Tare.

Beaver lamb

Sheep or lambskin with short fine wool, which has been dressed with the wool on, dyed and finished by a process giving a weather-resistant straightness and brightness to the wool.

See: Shearling.

Bellows hide

Curried, flexible and air-proof leather made from split hide.

Belly

1. The part of each side of a sheepskin or cattle hide which cover half the animal’s underside and the upper parts of the fore and hind legs;

2. The extreme left or right side of a cattle hide removed by cutting along a line parallel to the backbone line and such a distance from it determined for an individual hide by noting the change in feel from the denser structure of the crop, or butt, to the looser structure of the belly (USA). Includes belly middle, axillae or leg-pits  and shanks.

Belly grain

Tanned outer (hair or grain) layer split from a belly.

Belly grain

Damage caused by irritation by urine and dung, sometimes found

on the bellies and upper thighs of calf skins and shown in the

leather as unevenly roughened, or eroded, grain areas.

Belly strain

Mechanical damage caused to skins when they are pulled from the carcass. See: Butcher strain.

Belt filter

Filtration of sludge of a suitable consistency which is trapped between two filter belts and compressed through a system of rollers.

Belt leather

Leather used for waist belts as distinct from "transmission belting".

Belting lace

Chrome tanned back, about 2.5 mm thick, heavily dressed with natural grease, suitable for cutting into strips for the purpose of joining transmission belting.

Bend

Half of a cattle hide butt, obtained by dividing it along the line of the backbone.

Best Available Technique (BAT)

EU Definition: The most effective and advanced stage in the development of activities and their methods of operation which indicate the practical suitability of particular techniques. This will provide, in principle, the basis for emission limit values designed to prevent and, where that is not practicable, to reduce emissions and the impact on the environment as a whole. It also takes account of economic considerations.

Binder

Material used in finish preparations to achieve film formation and to fix pigments and other additives on the leather surface.

Binder leather

Vegetable tanned or chrome re-tanned butt leather of uniform thickness, dressed or impregnated to give it heat or abrasion resistance.

Bio-assay

Method for quantitatively determining the concentration of a substance by its effect on the growth of a suitable animal, plant or micro-organism under controlled conditions.

Biochemical Oxygen Demand (BOD)

The mass concentration of dissolved oxygen consumed under specified conditions by the biological oxidation of organic and/or inorganic matter in water.

Note: BOD5 is the mass concentration of dissolved oxygen consumed during 5 days.

Biocide

Agent or treatment that specifically kills micro-organisms.

Biodegradation

Molecular degradation of organic matter resulting from the complex action of living organisms ordinarily in an aqueous medium.

Biofilter

Attached-growth reactor using as bacterial support a granular material which ensures both the filtration of raw water and the biological degradation of the pollution it contains.

Biomass

Total mass of living matter in a given body of water. Activated sludge (unit g/l) is an example of biomass.

Birch tar oil

Oil obtained from the  bark of birch trees by dry distillation. Additive in fatliquors and finishing formulations to cover up offensive odour and to give a  pleasant “leather” smell.

BIT

See: 1,2-benzisothiazolin-3-one.

Blackening (of vegetable-tanned leather)

Operation of staining or dyeing vegetable tanned leather black.

Bleach (v); bleaching

To deprive of colour in a coloured material, as by exposure to the sun and weather or chemicals, in such a way as to remove, or lighten to the maximum its colour. To become colourless, pale or white.

Bleaching agent

Compound used in the process of making the colour paler in leather and textile fibres and fabrics, by treatment with chemicals or exposure to the sun and weather.

Bleaching extract

Vegetable tanning extract, usually heavily sulphited and containing additives, such as acids and water-soluble oils, used for bleaching vegetable tanned leather.

Bleaching tannin

Vegetable, or synthetic, tanning agent having the ability to render a leather paler in colour.

Bleeding

Passage of a component in solution from the interior of a solid onto the surface or onto another solid in contact with it.

Note: Dye from leather into a resin top finish.

Bleeding of tannin

Giving up of tannin in contact with water.

Blend (v); blending

Mix together and make into a more or less homogenous product various liquids, or powdered or granulated solids.

Blend (v); blending

To apply a dye solution to the hair coat in undyed furskins, to accentuate, level or slightly modify the natural colour.

Blind grain

Grain enamel that has been damaged by bacterial, mechanical or chemical action. See: Abraded or low grain.

Blind rib

Rib pattern which is generally not visible in the raw but becomes apparent, mainly in the neck and shoulder, when the skin is held up to the light in the limed state. See: Rib lines.

Blocking marks

Occurs when leather is piled finish to finish, flesh to flesh and the finish surface adheres, causing dull areas or even coats of finish being pulled away when the leather is separated.

Blood

Ox blood used as non-thermoplastic binder in finish preparations. Added to black or dark coloured leather improves the depth of colour and brilliance.

Blood albumen

Evaporated and dried blood serum, after removal of fibrin and corpuscles.

Blood vessels

Tube through which blood circulates in an animal body. When visible in leather the cause is usually poor bleeding or staleness, but can be breed related. See: Veins.

Bloom

Pale yellow to brown precipitate, consisting mainly of ellagic acid together with chebulinic acid, formed on the surface of, or within, vegetable tanned leather, or in a tan-pit when using liquors based upon ellagitannins, such as valonia, divi-divi, myrabolams, algarobilla, as well as oak bark.

Bloom (finishes)

Dullness of the finish or an uneven refraction of light within the film.

Note: Mild fatty spue or interaction between dyes and finish coat.

Bloom-forming tannin

Tanning material, or tannin, whose solution forms bloom on standing, (algarobilla, divi-divi, chestnut wood, myrabolams, oak bark and valonia).

See: Bloom.

Blotchy

Uneven application of finish by spray guns.

Blow fly strike

Scar or open wound left on sheepskin by blow fly attack.

Blue scale

Method to evaluate changes in the colour of a material, such as leather, due to natural or artificial light effect. It includes 8 degrees of change (8 = no change, 1 = total decolouring or change). See: Grey scale.

Blushing

White haze causing dulling of the finish caused by the absorption of moisture because of cooling from rapid evaporation of solvents in the finish.

Board (v); boarding

To work the grain side of a leather by hand with a cork-covered board or by a machine in order to restore and develop the natural grain.

Boarded grain

Grain pattern developed by boarding leather by hand or machine

Boarded leather

Leather that has been softened and the surface of which has been lightly creased by folding grain to grain and then working the fold across the leather to and fro by hand boarding or by means of a boarding machine.

See: Box calf; box side; morocco; willow calf; willow side.

Boardy leather

Leather that is stiffer than it should be.

BOD

See: Biochemical Oxygen Demand.

Boil (v); boiling

1. Transition of a substance from the liquid to the gaseous phase, taking place at a single temperature in pure substances and over a range of temperatures in mixtures.

2. Boiling test - empiric test to evaluate the resistance to temperature by dipping a piece of leather in boiling water and measuring the shrinkage of the area or of the size.

Boiling point

Temperature at which the tension vapour of the liquid is equal to the external pressure applied to it.

Bond

The way two atoms or groups link themselves. Note: Chelate, co-ordination, covalent, cystine, disulphide, electrovalent, ester, hydrogen, interchain, ionic, labile, peptydic.

Bookbinding leather

Leather of suitable thickness, durability and lightfastness, made mostly from sheep, goat, calf, pig and deer skins, usually vegetable tanned, but sometimes, specially in former times, alum-dressed.

Note: Used to bind books, documents and similar articles.

Bottom dyeing

Dyeing base, the lowest part, of a leather  to a desired colour before the application of a pigment finish or in final stage of dyeing.

Bound lipid

Lipid chemically combined with protein matter of the skin.

Bound water

Water held in a material by forces, as hydrogen bonds between it and polar groups.

Bovine leather

Leather made from bovine animals such as ox, heifer, cow, steer, zebu, etc.

Bovine Spongiform Encephalopathy (BSE)

Bovine Spongiform Encephalopathy is a newly (1986) diagnosed disease of cattle that has evolved rapidly into one of  the major veterinary - and human - medicine problems of the past few decades. It is included in the group of Transmissible Spongiform Encephalopathies (T.S.E’s).

T.S.E.’s are a class of rare brain diseases associated with the accumulation of abnormal proteins (Prion’s Theory) in the brains of man and animals. They are characterised by very slow development and the diseases are always fatal. The most common disease of this type is sheep scrapie ( first reported in 1732), the most publicised is BSE or “Mad Cow” disease (1986).

Since March 1996 BSE is related to the new variant of Creutzfeld - Jacob disease (CJD), a new degenerative fatal disease.

Box calf

Full chrome tanned calf leather, black or coloured, smooth or boarded.

Note: In the UK it must be black. When it is in other colours, see willow calf.

Box side

Full chrome or combination tanned leather made from cattle hide sides, black or coloured, smooth or boarded.

Note: In France the leather may also be synthetic tanned.

In the UK any tannage may be used but the leather must be black. When it is in other colours, see willow side.

Brand

Identification mark on the hide or skin of the animal which damages the grain. Applied by hot iron or chemical or freeze branding.

Brasilin

Colourless substance, which is oxidised to the brownish-red dye brasilein.

Note: Brasilin is present in red woods as a glucoside.

Break

Pattern of more or less fine creases formed when certain leathers, for example, box calf, are bent, grain inwards.

Breaking load

Force required to break a material of a specified size and shape under specific conditions, for example, leather.

Bridge

Chemical bond that links two different parts of a compound or polymer chain. Note: Cystine, ester, oxo.

Bridging

Link between two molecules or groups with a group or an atom. Note: Hydrogen bridge, disulphide bridge in keratin, methylene bridge, etc.

Bridle leather

Strong, flexible type of harness leather, made from ox or cow hide, vegetable tanned and curried, of reasonably uniform thickness with a plain finish and a close shaved flesh.

Brightening dye

Selected anionic dye which is added to the pigment base coat finish or to top coat preparations in order to enhance brilliance or the aniline effect.

Brightness-dullness value

Measure between the amounts of incident white light reflected and scattered, and that absorbed by a coloured material.

Brilliance

Ability of a finished leather surface to scatter and/or to reflect a high proportion of the incident light.

Brine

Water which contains salt at a high concentration.

Brine (v); brining

Salt-curing of hides by immersion in a saturated salt solution.

Brine conditioning

Effective control of the brining operation, ensuring solution remains saturated, clean, grease-free and free from micro-organism.

Brined hide

Hide cured by immersion in a saturated salt solution, drained and sometimes salted-down with solid salt.

Brining drum

Drum for brine curing of hides.

Bristle

Short, stiff hair, especially from hogs.

Brittleness

Property of a leather breaking suddenly, completely throughout its thickness, when bent to a comparatively small extent.

Bronze (v); bronzing

Unwanted metallic sheen or lustre often associated with build up of basic dyestuff on the surface of the leather. Can also occur with poorer quality inorganic pigments.

Bruise (v); bruising

Crowding or bumping of the animals or the use of a whip or club can cause a haemorrhage in the skin and underlying tissue. Although difficult to see from the grain side because of the hair, bruises can be visible from the flesh due to excess blood in the affected area. This can quickly putrefy and become a blemish or weak spot.

Brush (v); brushing

Leather is passed between rotating, stiff brushes to bring up the nap or to remove any surplus dust caused by buffing.

      Hand brushes or brushing machines are also used for the application of finishes for splits or coarse-fibred leather.

Brush dyeing

Apply a dye solution to a leather surface by brushing.

Brush dyeing

Dyeing of the hairs of a furskin by applying a dye solution with a brush.

Brush marks

Pattern of the brush used for applying a finish. May be caused by using finishing systems that “set up” too rapidly or by using coarse grade applicators.

Brush mordanting

Process of applying a mordant to a leather surface with a brush.

Brush mordanting

Application of a mordant solution to the top hair of a furskin, rather than the underfur, by means of a brush.

Brush off

Special effect, giving contrasting colours. The top coat of the finish is partially removed to reveal the underlying, contrasting colour.

BSE

See: Bovine Spongiform Encephalopathy.

Bubble (v); bubbling

Air trapped in the surface finish of the leather, either as intact or broken bubbles, giving an uneven appearance to the film.

Bubble diffuser

Aeration system by blowing compressed air into the liquid mass at depths varying from 1 to 10 metres.

Buck

Male deer, antelope, hare, rabbit or goat.

Buckskin

Suede leather made from deer skin from which the grain has been removed, usually by frizing. It is generally tanned with fish oil or aldehyde or a combination of both and may be finished on the flesh or the frized grain side.

Buff (v); buffing

Abrade or grind a leather surface, especially the grain surface, by a moving band of abrasive paper or cloth.

Buffed leather

Leather from which the top surface of the grain has been removed by an abrasive or bladed cylinder or, less generally, by hand.

Note: In the case of upholstery leather the buffing process is invariably carried out by the machine though it is sometimes incorrectly described as "hand buffed". See: Corrected grain; buff (v); buffing.

Buffer

Solution prepared to reduce and resist changes in pH (in the concentration of H₃O⁺).

Buffing depth

Regulation of the depth of buffing to achieve the desired effect on the finished leather.

Buffing dust

Dust obtained from the buffing operation.

Buffing ground

Special grounding agents, such as mucilages or synthetic resin dispersions, to improve the buffing properties of leather, especially for corrected grain leather.

Bundle

Group of parallel fibres.

Burns

Acid or alkali burns usually caused by lack of movement in the process vessel with a concentration of the chemical damaging the grain. Also high temperatures causing gelatinisation. Machinery can cause friction burns.

See: Glazing.

Burrs

Burrs, seeds and prickles from plants caught in the wool of sheep. These can penetrate the grain causing permanent damage.

Butcher strain

Mechanical damage caused to skins when they are pulled from the carcass. See: Belly strain.

Butt

Leather from that part of the hide left after removal of the bellies and shoulders.