R&D

See: Research & Development.

Raceway brining

Raceway, such as a tank shaped like a racecourse, in which brine solution and hides are moved around by a paddle, for brine curing of hides.

Radiation curing

Method of curing hides by radiation.

Rapid tannage

See: Quick tannage.

Rash

Skin reaction to insects, bacteria, chemicals etc. See: Dermatitis.

Raw hide lace

Buffalo hide, limed, unhaired, dried out and lightly oiled, cut into strips for the purpose of joining transmission belting.

Raw material

Unprocessed natural product used in manufacture.

Rawhide

A more or less translucent product, made from bovine hides, with the hair and flesh removed by liming, unhairing and fleshing, and dried out in the limed state, usually without any tanning treatment.

Rawhide trimmings

Pieces cut from raw hides or skins to give them a satisfactory shape.

Reactive dyestuff

Dyestuff that contains functional groups capable of forming covalent bonds with active sites in fibres, such as hydroxyl groups in cellulose, amino, thiol, and hydroxyl groups in wool or amino groups in polyamides. These are especially suitable for gloves and other garments required to withstand wet conditions and also dry-cleaning.

Reactive resin

Resin which contains reactive organic groups, that are capable of attaching to the fibre by chemical union.

Reconstituted leather

Made by forming leather fragments and fibres into sheet material with the aid of adhesives, resins, etc.

Recycle (v); recycling

Recovery and/or reuse of what would otherwise be a waste material.

Red heat

Red colouration found on the flesh side of salted hides after storage. Caused by salt tolerant (halophilic) bacteria that are aerobic so they stay on the surface of the hide. Long term storage of hides with red heat can lead to pitting of the surface. The origin of salt may influence the development of red heat, with marine salt containing high levels of halophilic bacteria compared to rock salt. Kiln dried solar evaporated salts have been found to be free of halophilic bacteria.

Reduced chrome liquor

Solution of trivalent chromium salts, mainly basic sulphates,  prepared by the reduction of a dichromate solution, by sulphur dioxide or by an organic substance, such as glucose, in the presence of acid; used for chrome tanning.

Re-dye (v); re-dyeing

Subject a previously dyed material (leather) to a second dyeing treatment, which could be in a similar or different colour.

Reed bed

Also called reed bed filters (RBF). The process does not rely on microbial degradation as a major process but uses the reactive/adsorptive potential of soil and the uptake by plants. A system successfully used for treatment of COD.

Reflesh (v); refleshing

To give hides or skins a second fleshing.

Refrigeration

1. The science of producing and maintaining temperature below that of the surrounding  atmosphere.

2. Extract heat from a body or substance by lowering the temperature of the body, such as a  hide or skin, and by keeping its temperature below that of its surroundings.

Rehydration

Absorption of water into dried hides, skins or leather.

Rein

Long, narrow leather strap, each end of which is attached to the bit and which is used to guide or check a horse.

Rejects

Hide, skin or leather of inferior quality to the established grades and usable only for poor quality articles or not at all.

Reliming

Second liming step.

Rendement

Yield figure for a vegetable-tanned leather calculated from its analysis, namely the weight of leather at 14 % moisture content per 100 parts hide substance.

Rendered tallow

Harder kinds of fat (melted down) obtained from cattle and sheep body tissue by rendering, using either a heat process or a heat and chemical process.

Render (v); rendering

1. Convert packing house (abattoir) waste, livestock carcasses and tannery waste, such as fleshings, into industrial fats and oils (for instance tallow for soap) and various other products (for instance fertilisers and protein supplement in feeding stuffs for livestock).

2.   Process of extracting, melting or clarifying fat.

Rendering plant

Unit for the treatment of animal carcasses and waste offal in order to recover products such as tallow. It is also a plant to treat some tannery waste (fleshings).

Repair bend

Sole leather bend produced for the repair of footwear.

See: Manufacturing bend.

Replacement tannin

Synthetic tanning agent which can largely, or entirely, replace the vegetable tannins without fundamentally altering the tanning process or the character of the finished leather.

Resalted

Treated with salt for a second time to ensure thorough saturation and hence better preserving properties.

Research & Development (R&D)

Work directed towards the innovation, introduction, and improvement of products and processes.

Reset (v); resetting

Treatment to increase the area of the hide or skin for the second time.

See: Set (v); setting out.

Reshaving

Giving hides and skins a second shaving to ensure a correct and level thickness. See: Shave (v); shaving.

Resin

Organic substance of natural origin, (exuded in the sap of trees and plants) with high-molecular weight, amorphous, and sticky. These substances could be insoluble in water, but soluble in several organic solvents.

Resin

Organic substance of synthetic resins, made by polymerisation or polycondensation, with similar properties to natural resins, such as the polyacrylates.

Resin binder

Material such as polyacrylate, for incorporation in a pigmented finish to fix the pigment and form a film.

Resin finished

Leather with a pigment finish, incorporating a synthetic resin binder.

Resin retannage

Second tannage with a resin, generally for filling purposes, applied in the post-tanning operation after the primary tannage.

Resin tannage

Deposition within the fibres of pelt, or leather, of high molecular, water-insoluble polymerisation, polyaddition or condensation, products without these and the fibres necessarily combining.

Note: Resin tannin.

Resin tannin

High molecular weight organic polymerisation, or condensation, product deposited within the fibres of pelt or leather without combination necessarily occurring; introduced either as a water solution and deposited through subsequent growth of molecular size (urea or melamine/formaldehyde condensates, vinyl or acrylic compounds) or as water dispersions (dicyandiamide/ formaldehyde condensates); used for pre-tanning and for filling leather.

Resin top coat

Synthetic resin used as a film-forming agent to give a protective top coat.

Resinous spue

Resinous exudation onto the surface of leather, which may be difficult to dissolve in organic solvents.

Resist

Substance which is applied to the tips of the hairs of furskins to protect them from uptake of dye whilst the shafts are dyed.

Resist wax

Wax mixture applied to the elevated areas of an embossed leather to prevent these taking up dye.

Note: Used in the preparation of  “antique” leathers.

Resistance to hydrolysis

Resistance of a compound to being hydrolysed.

Restraining action

Slow down the dye uptake, by means of certain ionogenic (inorganic and organic) auxiliaries.

Retan (v); retanning

Subject an already tanned leather to a further tanning treatment to modify its properties, using an agent of the same, or entirely different, type.

Retannage

Modifying second tanning treatment, applied to leather that has already received a primary tannage to modify some of its properties, using an agent of the same, or an entirely different, type.

Retanned leather

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

Retanning material

Substance of diverse chemical properties able to be used in the retannage to impart specific properties to the leather.

Reticular layer

The deeper layer of the dermis formed by interlacing fascicle of white fibrous tissue.

See: Dermis.

Reticular tissue

The inner, thick, dense layer of the dermis that blends into the subcutaneous connective tissue. Reticular tissue, because of its netlike structure is also known as ‘fibre network layer’. The reticular tissue forms the major part of leather, hence the properties of leather depend to a considerable extent upon the condition of the reticular tissue in the finished leather.

Reverse calf

Water-resistant suede calf leather finished on the flesh side.

Reverse coating

Application of finishes by a roller coater where the print roll is counter-rotating to the leather fed through the machine.

Reverse lamb

High-grade gloving leather with a suede finish on the flesh side, made from the skins of slink or unweaned lambskins.

Reverse Osmosis (RO)

Filtration process which consists of applying greater pressure on the water than the osmotic pressure, in order to force the water to pass through a semi-permeable membrane against the direction taken by the natural osmosis process. This technique is used in the production of drinking water from salt or brackish water. It retains particles of between 0,01 nanometre and 1,0 nanometre.

Reverse side

Water-resistant suede side leather finished on the flesh side.

Rewetting

See: Condition (v); conditioning.

Rib lines

Generally not visible in the raw but become apparent mainly in the neck and shoulder when the skin is held up to the light in the limed state. See: Blind rib.

Ribbiness

Naturally occurring defect in woolled sheepskins, especially of the merino, finer wool types, consisting of numerous long, raised ridges on the surface, usually running across it in parallel lines from the backbone to the belly and flanks.

Ringworm

Naturally occurring defect in woolled sheepskins, especially of the merino, finer wool types, consisting of numerous long, raised ridges on the surface, usually running across it in parallel lines from the backbone to the belly and flanks.

Rinse (v); rinsing

Cleansing of a material with a stream of running water.

RO

See: Reverse Osmosis.

Rock salt

Common salt obtained by direct mining of underground deposits in contrast to that obtained by evaporation of brines or solar evaporation. Calcium, potassium and magnesium compounds commonly occur with rock salt.

Roll (v); rolling

Mechanical process after drying performed, for example, on vegetable tanned sole leathers. The purpose is to give the leather fibre structure a high density by high pressure to improve the stiffness and water resistance.

Roller coating

Application of finishes by a roller coater machine. Most advanced and most economical coating of leather.

Roller leather

Leather with compact structure, smooth, fine grain, of high resistance to abrasion, smooth flesh side and firm feel; made from chrome, chrome/synthetic or synthetic tanned calfskins or sometimes sheepskin, for high draft belting in cotton spinning machinery, or from skins of calf or close structure sheep, mainly in natural colour or dyed red for covering rollers in such machinery. When used for belting it is sometimes interlaid with different colour synthetic materials. Uniform thickness of a tolerance not exceeding ± 0,05 mm is essential.

Rope damage

If rope is used for tying bundles of hides and skins for shipping, the rope should be oil-free. Oiled rope may form stains on the hides which will show in the finished leather.

Ross

Outer, scaly layer of the bark of older trees.

Rough tanned leather

Leather which after tanning has not been further processed.

Note: It can be in a damp or dry condition. Differentiation is made between (a) wet blue leather which has not been fat-liquored and is in a damp condition and (b) crust leather which has been vegetable, chrome or combination tanned and which has been dried.

In the UK the term "rough tanned" is used chiefly in connection with vegetable tanned hide leather, such as rough tanned strap butts. See: Crust leather.

Roughing

Imparting a rough surface by abrasion.

Roughness

Rough surface feel to the finish of the leather. Possible causes are poor buffing, contamination in the finish, solvent finish too dry

Note: The solvent evaporates even before the finish reaches the surface of the leather, etc.

Round feel

Term used to describe the feel of a leather which is full, soft and flexible.

Rove

Apple-like gall on Quercus infectoria, produced by insect Cynips insana.

Rub (v); rubbing

To polish or abrade a material.

Rubbed grain

Grain enamel that has been damaged by bacterial, mechanical or chemical action. See: Low grain/sueded grain.

Rubbing off polishing

See: Brush off.

Run (v); running

Paddle or drum goods, continuously or intermittently, to treat hides and skins in different operations in beamhouse, tanning and post-tanning.

Run mark

If concentrated chemicals come into direct contact with hides or skins, damage can be caused. This damage is seen in the form of run marks where the concentrated chemical has spread over an area of the hide.

Note: Alkali, acid or chrome run marks.

Run pelt

Sheepskin dewoolled by sweating whose grain and flesh surfaces have become pitted, or liquefied, in spots by a worm-like organism.

Russet leather

Vegetable tanned cattle hide leather which has been dressed ready for staining or finishing.

Note: In Austria see: Cowhide.

In France this term is also applied to finished leather.

In the UK sometimes termed "skirt leather". The leather may now be combination or chrome tanned.

Russia calf

A calf leather tanned with the bark of willow, poplar and larch, curried on the flesh side with a mixture containing birch tar oil which gives it a characteristic odour.

Russia leather

Smooth finished, dyed side or calf leather scented with birch tar oil, vegetable tanned and made in imitation of the old-fashioned genuine Russia calf. Now also chrome or combination tanned and given water-repellent properties.