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C.I.E.	Commission Internationale d’Eclaraige (= I.C.I. International Committee of Illumination). This Commission defined some standard illuminants, and observers.
C.I.E. triangle (thrichromatic diagram)	C.I.E. trichromatic components, which represent the sensitivity of the eye to red, green and blue and defined the colorimetric reference observer.
C.I.E.L.A.B. co-ordinates system	CIELAB colour space is a system to represent the tristimulus values in which there is a plane (A-B) with the bright colours and a perpendicular axis (L) on which white-black is represented.
Calfskin	Skin from a young bovine animal not exceeding a certain weight, which varies from country to country.
Canaigre	Plant growing in Mexico and California, whose tuberous roots contain 18% to 43% tannin. Note: Rumex hymenosepalus.
CAP	See: Common Agricultural Policy.
Cape leather	Originally a soft, grain gloving or clothing leather made from South African hair sheepskin; now any similar leather made from hair sheepskin, but not finished leather made from East Indian  native vegetable tanned hair sheepskin.
Carbon dioxide	A heavy, colourless, odourless gas, present in the atmosphere or formed by the burning of fuels. Carbon dioxide is also exhaled by animals and used by plants in photosynthesis. It is also produced during biomethanation.
Carbon dioxide deliming	Deliming by means of carbon dioxide.
Carcinogen	Substance or preparation which, by inhalation, ingestion or skin penetration is believed to cause cancer in humans.
Carding leather	Butt leather, vegetable (originally, oak bark) tanned, lightly curried and fairly flexible, for holding the steel wires that form the periphery of the cylinders on the carding machines used in the woollen industry.
Carpincho	Grain gloving leather with a grain pattern somewhat like that of peccary, made from the skin of a water rodent indigenous to Argentina, Uruguay and Brazil. Note: One of the leathers commonly designated as Hogskin.
Cascalote	Pods of a tree found in Mexico. Note: Caesalpina cacolaco.
Case hardening	Outer surfaces of the hide or skin are tanned too rapidly thus preventing the tan liquor reaching the interior of the skin. Excessive build up of tanning agent on the surface leads to hardening and even eventual cracking of the grain.
Casein	Protein obtained from skimmed milk by precipitation with hydrochloric acid and used in finishes. Dried casein is available in a great number of commercial products having different viscosities depending on their application and composition.
Catechin tannin	Strictly speaking a tannin somehow formed from a catechin  (5 : 7 : 3’ : 4’ tetrahydroxyflavan – 3 – ol) unit ( gambier), but also sometimes applied to tannins formed from related units, such as a trihydroxyflavan-3-ol (quebracho) or a trihydroxyflavan-3-4-diol (mimosa).
Catechol tannin	Tannin presumed to contain a catechol nucleus because it gives a green colour with a ferric salt or yields fragments with a catechol nucleus on alkaline fusion.
Cationic dyestuff	Ion, molecule or radical from a dyestuff with a positive charge.
Cationic fatliquor	Ion, molecule or radical from a fatliquor (oil globules) with a positive charge.
Cationic resin	Ion, molecule or radical from a resin (organic substance) with a positive charge.
Cationic soap	Ion, molecule or radical from a cleansing substance with a positive charge.
Cationic surfactant	Ion, molecule or radical from a surfactant with a positive charge.
Cauliflower effect	Loss of substance during wet processing due to vertical fibre effect, leads to a “cauliflower” like pattern on the flesh side. See: Vertical fibre.
Cellulose aceto butyrate lacquer	Film-forming product in finishes, abbreviated CAB. Good stability to yellowing on exposure to light and heat. Excellent fastness to migration and resistance to free amines of polyurethane foams.
Centrifugation	Partially separating sludge contained in water by means of centrifugal force.
CFC	See: Chloro Fluorocarbon.
Chain	Chain of molecules bound to each other to form a new chain. For example, a chain of amino acids to form a protein or a chain of monomers to form a polymer.
Chamois	Leather made from the flesh of sheep or lambskin, or from sheep or lambskin from which the grain has been removed by frizing, and tanned by processes involving the oxidation of fish or marine animal oils in the skin, using either solely such oils (full oil chamois) or firstly, aldehyde and then such oils (combination chamois). Note: France and the USA restrict the term "chamois", without any qualification, to the flesh split of sheepskin tanned solely with oils. In Germany the term "Sämischleder" is applied to an oil tanned suede leather made from sheep, lamb, roedeer, red deer, chamois, goat and kid skins and cattle hide splits. In Italy and Switzerland this leather is incorrectly termed "pelle di daino" and "Hirschleder" respectively.
Chamois tannage	See: Oil tannage.
Chatter marks	Ridges in leather caused by fleshing, shaving or splitting machines where the cylinders are worn, poorly balanced or the bearings on the grinders may be worn. “Wire edges” on the cylinder will also cause chatter marks.
Chemical coagulation	Destabilisation of colloidal particles brought about by the addition of a chemical reagent known as a coagulant.
Chemical Oxygen Demand (COD)	Analytical determination of the amount of oxygen chemically consumed by the oxidation of the organic or oxidisable inorganic matter in an effluent. Potassium dichromate is used as oxidant.
Chilling	Hides chilled down immediately after flaying to between 8 °C and 10 °C can be stored over a week, as is done today in some areas for fresh hide processing. This chilling can be successfully achieved by distribution of shredded ice on the flesh side of the hides and storage in boxes. Dipping or spraying with chilled fresh water also can be used, and is also in current practice.
Chlorinated hydrocarbon	Organic substance (hydrocarbons) treated to combine with chlorine.
Chlorinated-paraffin wax	Solid, wax-like mixture of chlorinated higher paraffin hydrocarbons.
Chloro Fluorocarbon (CFC)	Any of a class of gaseous compounds of carbon, hydrogen, chlorine, and fluorine, used in refrigerants, aerosol propellants, etc., and harmful to the ozone layer in the earth's atmosphere owing to the release of chlorine on exposure to solar ultraviolet rays.
Cholesterol	Sterol produced by all vertebrate cells, particularly in the liver, skin and intestine. It is a component of the animal fatty materials.
Chondroitin sulphate	Nitrogenous  polysaccharide occurring in cartilage and in the interfibrillary material of hides and skins in the form of condroitinsulphuric acid.
Chromatic triangle	Triangular diagram with the three primary radiations (red, blue, green) placed at the corners. Mixing the primary colours, in varying proportions, it could produce all the colours.
Chromaticity	Quality of a colour which is defined by its dominant or complementary wavelength, taken together with its purity.
Chromatin	Protoplasmatic substance in a cell nucleus forming chromosomes, staining intensely with basic dyes.
Chromatogram	Result of chromatography. In Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC) and Ion-exchange Chromatography (IC), it is a diagram where peaks represent different compounds separated by the chromatography from a mixture.
Chromatography	Method of separating and analysing mixtures of chemical substances. Note: Gel permeation, thin layer, ion-exchange, two-dimensional, absorption, ascending, column, descending, liquid, paper, partition. See: High Performance Liquid Chromatography (HPLC)
Chrome (v); chroming	Treat hides and skins with chrome liquor for tanning.
Chrome complex dyestuff	Anionic dyestuff containing metal chrome complexes, type 1:1 or 1:2.
Chrome complex, (chromium) (cationic, anionic, neutral)	Complex formed by the co-ordination of various ligands to one or more Cr+++ ions, which may have a net positive (cationic), negative (anionic) or zero (neutral) charge.
Chrome leather	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.
Chrome liquor	Basic chromium sulphate liquor prepared by reduction of a dichromate by glucose in the presence of sulphuric acid.
Chrome mordant dye	Dye, which  needs a mordant to fix. Note: Chrome as a metallic salt could be a mordant.
Chrome oxide	Dark green, amorphous powder, forming hexagonal crystals on heating that are insoluble in water or acids; used as a pigment to colour wares and as a catalyst. Also known as chrome green. The chromium content of a chrome tanned leather and of a chrome tanning material is usually expressed as chrome oxide (Cr2O3) content.
Chrome retanned leather	Second tannage treatment of a leather tanned with chrome tanning salt, and then with other tanning materials. Note: As vegetable tanning.
Chrome stain	Irregular shaped darker coloured area on chrome leather, seen after tannage, due to increased deposition of chromium compounds, often related to too rapid basification.
Chrome tanning	Chrome tanning using a single solution of a basic trivalent chromium salt, usually primarily the sulphate.
Chrome tanning salt, (liquid; powder)	Commercial preparation of basic chromium sulphate, of a certain basicity, containing more or less of neutral salts; in the liquid, or powder, form.
Chrome-alum liquor	Basic chromium sulphate liquor prepared from chrome alum by addition of an alkaline substance, usually sodium carbonate.
Chromium	Metallic chemical element, symbol Cr, atomic number 24, atomic weight 51,996. ·    Hexavalent: the hexavalent form (Cr+6 or CrVI) of chromium ion as in chromates and bichromates. It has no tanning properties. ·    Trivalent: the trivalent form (Cr+3 or CrIII) of chromium ion as in chrome sulphate, chloride, etc. This is the chrome tanning form. ·    Total: The chromium content in leather, float, wastewaters, etc. in whatever form it is.
Chromophoric group	Group of atoms, such as –N=N-, -C=C-, =C=O, -N=O, in an organic substance which, when present in suitable structural positions, and in sufficient numbers, enables electron displacement to occur along the group or groups, and gives rise to colour.
Chrysoidine	Monoazoic basic dye.
CITES	CITES is an abbreviation for the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Also known as the Washington Convention, as CITES was signed in Washington DC on 3 March 1973 and came into force on 1 July 1975. The purpose is to control the exploitation of wild animals and plant resources. CITES has established a worldwide system of controls on international trade in threatened wild life and products derived from them by stipulating that government permits shall be required for such trade.
Clarifier	Settling tank  which allows activated sludge to be separated from purified water.
Clariflocculator	Device in which the floc is settled. The floc is obtained by agglomeration of destabilised particles into microfloc and later in bulky flocules.
Classification (for chemicals)	European classification of chemical substances or preparations explaining the risk associated with their use. The possible classifications are : Explosive, Oxidising, Extremely flammable, Highly flammable, Very toxic, Toxic, Harmful, Corrosive, Irritant, Sensitising, Carcinogenic, Mutagenic, Reproductive toxic, Dangerous for the Environment.
Claws	Pointed, horny nails or protrusions, from the feet of certain animals and birds.
Clean (v); cleaning	Removing dirt, spots and impurities from the surface of a material. It may be performed dry and/or wet. For example, by solvent.
Cleanability	Ability of an upper or clothing leather to be maintained in a clean and good condition.
Clear (v); clearing	Cleanse the leather grain surface from grease, etc., prior to seasoning by rubbing over with a solution of ammonia or lactic acid.
Clear grain	Grain surface free from blemishes or stains.
Clear lacquer	Pigment-free transparent lacquer used in finishes, especially as top coating agent.
Clone (v); cloning	Create genetically identical copies of a population of organisms derived originally from a single individual. To clone an animal or a plant means to propagate or produce it as a clone, for example create genetically identical copies. A clone is an animal or plant that has been produced artificially from the cells of another animal or plant, and is identical to the original one.
Closed grain	Tight formation of the surface grain on leather.
Clothing leather	Soft, flexible, non-stretchy, grain or suede leather of a thickness suitable for clothing. It may be made from full substance, or split, hides or skins and tanned in various ways. Note: It should be fast to light, perspiration and wet and dry rubbing and be capable of being washed or dry cleaned.
Cloudy	Visible uneven appearance caused by transparent or opaque whitish blush on the surface of the finished leather.
Clumping	Aggregation of small particles into larger ones, as a thick cluster, difficult to break up. This process occurs if an aqueous solution is added to a powder pigment instead of stirring the powder into the solution.
Coagulant	Soluble substance which under certain conditions, such as rise of temperature, pH alteration or chemical action, forms a semi-solid or jelly-like insoluble precipitate, which can carry along fine suspended solids. Note: Ferrous sulphate, organic polyelectrolytes.
Coagulate (v); coagulating	Cause a substance in solution to separate out as large particles, or to change to an insoluble form and separate from solution as large aggregates. Note: As do blood globulins when their solutions are heated.
Coagulation (of finishing products)	Finishing products are often susceptible to extreme temperatures. Frost will cause aqueous-based finishes and especially thermoplastic binders to coagulate irreversibly. Heat will cause irreversible coagulation of albumens and globulins.
Coagulation-flocculation	Process of injecting one or more chemical products with the objective of destabilising dispersed colloidal matter, aggregating it and then agglomerating it into large separable particles.
Coarse emulsion	Emulsion in which dispersed droplets are comparatively large.
Coarse grain	Grain surface that is somewhat rough, due to the nature of the pelt and the method of treatment during tannage etc., and in which the hair or wool follicles are large, forming a prominent pattern.
Coarse woolled	Sheep having long, strong, coarse fibre wool especially suitable for carpet manufacture, such as various large mutton breeds of English origin. The impression of coarseness or fineness is given by the diameter of the individual fibre. The smaller the diameter the finer the fleece cover will feel. Coarse woolled  sheep breeds are covered with a low density wool coat of medullated ‘thick’ fibres that can have - in the coarsest types - a diameter over 38 ìm (1000 ìm= 1 mm). Comparatively, the finer wool types, such as merino, have a fibre diameter of approx. 18 ìm to 26 ìm.
Coarse-pored leather	Leather whose grain shows large pores which can be improved by buffing. See: Fine-pored leather.
Coat (v); coating	Application of liquid system, such as a dye solution, or a pigmented finish, to a material such as leather. See: Brushing; padding; spraying; curtain coating.
Cockle (Keds)	Defect on sheepskins (rib cockle), first recognisable after unhairing and appearing on the grain surface as small, firm nodules, usually over the butt, in lines running at right angles to the backbone towards the flanks. It is due to infestation by keds. Scatter or spread cockle is more diffusely spread over the skin and has been linked to lice. Note: Ked - melophagus ovinus.
Coconut oil	Oil from the kernels of the fruit of the coconut palm.
COD	See: Chemical Oxygen Demand.
Coil	Continuous length of material in a spiral shape like the thread of a screw. For example, collagen helix.
Cold crack	Possible damage to a finish film when the leather is flexed at low temperatures. Shoe uppers, therefore, need cold crack stability.
Cold stuffing	Introduction of a mixture of oils, fats and waxes into damp leather at room temperature by hand, drumming or impregnation.
Cold sweating	Process of loosening the hair or wool of hides or skins by keeping them damp and cool (up to about 12 °C) so that bacteria develop and attack the hair roots and lower epidermal layer.
Cold-stable	Oil which does not deposit solid fatty matter on cooling to a specified temperature.
Collagen	Protein comprising the white fibres of vertebrate connective tissue, such as the dermis of skin, the matrix of bones and the dentine of teeth. Collagen is the leather making protein of the hide. Collagen in the hide or skin is perfectly structured to act as a protective covering for all animals and these same features are ideally suited for additional processing as an accessory for man (1997 IULTCS Congress, London). Dermis, the leather giving layer of the hide or skin, after the removal of epidermis, hair and flesh layer, is almost entirely collagen. In the animal kingdom, this bio-polymer is unique in its amino acid composition, structural diversity and physical properties. The basic structure of the collagen molecule is simple. The key to its ubiquitous presence is the ability of nature to modify this simple structure so that the biological diversity of the collagenous structures and their functions are unequalled by any other protein. At the time of the Centenary Congress (1997) of the International Union of Leather Technologists and Chemists Societies (iultcs) in London, 19 genetically distinct collagens were known. The fibres of the leather giving layer dermis are copolymers of the major type I - fibrous collagen,  together with minor amounts of collagen types III (fibrous), V (fibrous), VI (filamentous), and possibly XII (fibril associated collagen). See:  Ageing;  amino acid; angle of weave; bond; dermis;  denaturation; structural features; hydroxyproline;  isoelectric point; grain layer; papillary layer; reticular layer; maturity; interfibrillary matter
Collagenase	Enzyme which hydrolyses collagen, a substance that accounts for 75% of the dry weight of skin tissue.
Colloidal suspension	Describes particles - often electrically charged - which are dispersed in a fluid but fail to settle naturally. This term is also used for fine suspended solids which settle only with considerable difficulty. They can be removed by coagulation - flocculation.
Colophony	Yellowish, glassy resin obtained as a residue from the distillation of turpentine, an exudation from certain pine trees.
Colour	Visual sensation produced on the eye by radiation of bodies or substances, reaching it after reflection or scattering by a surface or transmission through a material. These special characteristics depending upon the spectral composition of the wavelengths of radiant energy capable of stimulating the return and its associated neural mechanisms. This sensation is defined by three characteristics: Value (or intensity), hue or tone, and croma.
Colour (v); colouring	Apply or give colour to a material, as by dyeing, painting or staining.
Colour base	Insoluble organic substance which, when dissolved in acid, gives a dyeing cation.
Colour change	Alteration in the colour of a coloured material produced by chemical treatment, alteration of pH, light, etc.
Colour circle	Circle designed to exhibit the proportion of primary colour in any shade of colour.
Colour levelness	Visible evenness of the coloured surface of a dyed or finished leather.
Colour matching	Application of an adequate blend of dyestuffs to a material, such as leather, to obtain and duplicate the same colour as that of a sample in any kind of material.
Colour shop	Place (zone, area, or department) where colour recipes are prepared.
Colour sorting	Classification of dyed skins with similar colour for making a leather garment.
Colour stripping	Lose the colour from a material, by chemical treatment or sunlight effect.
Colour triangle	Triangular diagram showing the three primary colours (red, green, blue) placed at the corners. Mixture of any two primaries will be found in the line joining the corners, and the centre of the triangle will, theoretically, be black..
Combination chamois	Chamois tanned by using aldehyde prior to fish or marine animal oils.
Combination oil tannage