Alphabetical Search

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Pad (v); padding	Application of finish coats, by manual padding with a plush-covered pad or by a padding machine using pads, mechanically moving to and fro across the leather surface.
Pad marks	Marks left by a plush-covered pad used for applying pigment finish. The marks are visible as streaks and can be caused by an uneven surface on the pad or poor flow-out of the finish.
Paddle (vat)	Semi-cylindrical vessel (of metallic, wood, concrete or plastic materials) fitted with a revolving paddle wheel for keeping skins and liquors in motion. This type of vessel could be used in different beamhouse processes such as soaking, liming, and rinsing.
Paddle dyeing	Dyeing in a paddle or vat fitted with rotating blades, to keep the contents in motion.
Paddle liming	Liming of hides, or skins, in a paddle.
Paint (depilatory)	Pasty, aqueous mixture, applied to the flesh side of certain hides and skins, especially sheep and goat skins, to loosen the hair or wool. Note: Mixture of slaked lime and sodium sulphide or of an enzyme and a thickener.
Paint (v); painting	Application of a pasty, aqueous, depilatory mixture (paint) to the flesh side of certain hides or skins, especially sheep and goat skins, to loosen the hair or wool.
Paint marks	Water resistant and lightfast pigment formulation applied to a domesticated animal (especially sheep), that indicates its owner, class, etc.
Painted hair	Hair removed from hides or skins after loosening by application of a depilatory paint to the flesh side.
Painted wool	Wool removed from sheepskins after loosening by sulphide paint applied to the flesh side.
Pancreatic enzyme	Enzyme originating from the pancreas, often used in bating.
Papillary layer	Papillary dermis is commonly referred to as the papillary layer  or the ‘thermostat layer’. The papillary dermis or thermostat layer contains hair, hair follicles, sebaceous glands, sweat glands, erector pili muscles, etc. Surrounded and supported by connective tissue (collagen) fibres.
Parchment	A translucent or opaque skin material, having a smooth surface, suitable for manuscripts, bookbinding and other purposes. Made from calf, sheep and other unsplit skins by drying the dehaired, limed skin without applying any tannage, the material being thoroughly cleansed and degreased and the grain surface being smoothed during the process. In the UK parchment is made from the flesh split of a sheepskin. In other EU countries parchment may be made from any type of skin. See: Vellum.
Paste (v); pasting	Mix a dye powder with water or other liquid, to obtain a paste for dyeing.
Paste (v); pasting	Process of sticking wet leather to a smooth plate for drying. See: Paste drying.
Paste drying	Drying method mostly used for upper leather with corrected grain. A glass plate is covered with a thin starch paste and the wet leather is slicked out, grain side to the glass, to which it adheres thereby preventing shrinkage on drying in the drying chamber.
Pastel	Character of a delicately coloured surface, scattering, emitting and/or reflecting a high proportion of incident white light.
Pasteurisation	Pasteurisation aims at making a product aseptic. By way of example, the use of sludge on pastureland. Pasteurisation can be achieved by heating the sludge  to 70 °C for 30 minutes.
Pasting agent	Glue, such as carboxymethyl-cellulose or starch paste, used to stick the wet leather on to the glass plate during paste drying.
Patchiness	Uneven colour due to irregular uptake of dyes.
Patent laminated leather	Plastic surfaced laminated leather with the appearance of patent leather.
Patent leather	Leather with a lustrous mirror-like surface, built up by the application of one or more coats or daubs, varnishes or lacquers, pigmented or non-pigmented, based on linseed oil, nitrocellulose, polyurethane and/or other synthetic resins. Note: In certain countries laminates of a similar appearance may be classed as patent leather, but different countries limit the proportion or thickness of the plastic film in different ways.
PCP	See: Pentachlorophenol.
Pearlised leather	Coloured leather with a pearlised lustre.
Pebbled grain	Wrinkled grain layer caused by the corium contracting during the tannage more than the grain layer, which therefore seems to be “drawn up”. Can be caused by excessive agitation in the process vessel or chemically. See: Drawn grain.
Peccary	Grain leather, mainly gloving, made from a wild boar indigenous to Mexico, Central American countries, Brazil and Argentina.
Peel (v); peeling	Undesired removal of a thin layer of finish from the leather surface.
Peeling Grain	Grain layer separates from the corium. Usual causes are too high a temperature during storage and processing, as well as bacterial damage.
Pelt	Skin in the trimmed, dehaired or dewoolled, limed, fleshed, perhaps bated, and scudded condition. In other words, the isolated corium layer more or less ready for tanning.
Pelt split	Split in the fully hydrated and untanned state, as cut from skins after removal of the hair or wool, epidermis and flesh layer.
Pelt trimmings	Pieces cut from pelt to give them a satisfactory shape.
Pelt weight	Weight of pickled, dewoolled sheepskins.
Penetrate (v); penetrating	Enter one material into or through another. Note: Liquor, solution or dissolved chemical, into leather.
Penetrating ability (of a dyestuff)	Ability of a dyestuff during dyeing to penetrate into the interior structure of a material.
Penetration time	Time needed for the required degree of penetration of a chemical into the inner layers of the leather.
Penetrative dyeing	Dyeing which penetrates deeply into a material.
Penetrometer	Device to measure the dynamic water resistance of flexible leathers. The penetration time, water absorption and water transmission are all recorded.
Pentachlorophenol (PCP)	Chemical substance sometimes used as a preservative in leather, wood, cotton and other natural materials.
Peptidase	An enzyme which hydrolyses the peptide links of polypeptides, though not of native proteins.
Peptide	Any compound in which two or more amino acids are linked together in a linear sequence, the carboxyl group of each acid being joined to the amino group of the next. Depending upon the number of amino acid residues per molecule, they are known as dipeptides, tripeptides, and so on, and finally polypeptides.
Perch (v); perching	Softening and stretching method for light leathers by means of a perching machine with a bladed cylinder.
Perchloroethylene washing fastness	Fastness (mainly colour fastness) of a dyed leather to a perchloroethylene washing test (dry cleaning).
Perforation	Holes punched in shoe uppers for decorative effect. The holes are punched by machine according to pre-designed patterns, usually before the parts are stitched together.
Permeometer	Device for measuring the coefficient of permeability by measuring the flow of fluid through a sample across which there is a pressure drop produced by gravity.
Persian	Crust, vegetable tanned leather made from the hair type sheepskin originating in the Indian sub-continent and tanned in India, mainly in the South, and especially around Madras (Chennai).
Persian	Leather made from crust, vegetable tanned leather made from the hair type sheepskin originating in the Indian sub-continent and tanned in India, mainly in the South, and especially around Madras (Chennai).
Persian skiver	Thin grain layer, split after dressing from an E.I. (East Indian) tanned sheepskin.
pH	Term used to describe the hydrogen-ion activity of a system, that is the acidity or the alkalinity. The pH range is generally from 0 to 14, with pH 7 being neutral. Less than pH 7 is acid, with pH 0 being the strongest acidity. Above pH 7 is alkali, with pH 14 being the strongest alkalinity.
pH Difference figure	Difference between the pH of a solution, for example, water extract of a leather, and the pH of the same solution diluted ten-fold. It is an index referring to the amount of free acid. Often shown as “D pH”.
Phlobaphenes	Reddish-coloured, more or less insoluble condensation products formed by the condensed tannins, such as quebracho, mimosa and oak barks, when their solutions are boiled with acid or are allowed to stand.
Phosphatide tannage	Tannage with phosphatide-containing materials, such as brains, bone marrow and egg yolk.
Phospholipids	Compound whose products of hydrolysis include fatty acids and phosphoric acid; any lipid containing phosphoric acid, especially one with a structure based on glycerol phosphate.
Picking band leather	Butt or sometimes shoulder leather with or without the hair, combination tanned (such as oil/vegetable) or chrome tanned, curried to produce leather with high tensile, tear and flexural strength, for use on textile looms.
Pickle	Acid liquor, such  as  sulphuric acid and sodium chloride, used to preserve pelts and hides and to prepare them for tanning.
Pickle  meal	Pickle prepared from fermented oats, barley, etc., and salt.
Pickle (v); pickling	Treatment of pelts with an acid liquor, such as a solution of sulphuric acid and sodium chloride, to preserve them or to prepare them for tanning, especially chrome tanning.
Pickle creases	Occurs during the storage and/or transport of pickled stock. The creases are caused by the partial drying out of the stock.
Pickled weight	Weight of hides or skins after the pickling process and draining to approximately 55% to 60% moisture.
Pigment coat	Finishing coat using organic or inorganic pigments in the finish preparation.
Pigment finished leather	Leather to whose surface a finish containing fine pigment particles in suspension has been applied. Sometimes called “doped”.
Pigment paste	Homogenised, finely dispersed pigment paste manufactured by chemical suppliers. Mainly offered with ready-to-use consistency.
Pigskin	1. Skin of a swine; in Britain the term applies to all swine; in the United States to younger swine weighing less than 50 kilograms, the ‘heavier’ being called ‘hog’; hog-skin = pigskin. 2. Leather made of  pigskin.
Pile (v); piling	Lay wet tanned hides flat in a pile to drain and allow the tanning agent to become fixed.
Pilling	Forming of small balls when a resin finish is applied by padding or brushing. Usually caused by the presence of buffing dust or poor mechanical shear of the resin. See: Balling up.
Pin seal	Seal skin leather with a characteristic very fine pinhead pattern obtained by hand boarding.
Pinhole - Bovine	Enlargement of the individual hair follicles due to bacterial damage.
Pinhole - Ovine	Defect of fine woolled sheepskins consisting of prominent small holes penetrating the skin to a considerable depth but not through it. Caused by the gaps left  by groups of wool fibres which grow together in clumps and are pulled out together during dewoolling.
Pinned vegetable sole leather	Set out and rolled leather made from vegetable tanned cattle hide belly or shoulder.
Pit liming	Liming of hides, or skins, in a pit.
Pit salted	Curing of hides and skins by placing in a pit one by one, flesh-side upwards, sprinkling each with solid salt as it is introduced and leaving in its own liquor until required.
Pit soaking	Soaking of hides or skins in a pit.
Pit tannage	Tannage, mostly for vegetable-tanned sole leather, carried out in a series of pits.
Pitting	Indentations in the grain of the hide caused by large crystals of salt. The pressure of the pile of hide adds to the formation of pitted areas.
Plastic surface laminated leather	Leather covered with a sheet or film of plastic or other artificial material. Note: Different countries limit the proportion or thickness of the plastic film in different ways. In the EU, Directive 94/11/EC dated 23 March 1994 lays down that if the synthetic layer is thicker than 0,15 mm but less than one third of the total thickness, the composite must be defined as "coated leather".
Plasticity	Ability of a solid material, such as a finish film, to be deformed, bent or stretched, without damage, and retaining the newly acquired shape.
Plasticiser	Finishing agent added to a finish to increase the stretchiness and elasticity of the coat and to render the film flexible during storage and use of the final leather products.
Plastometer	Equipment to measure the tendency of a leather to recover the initial shape and surface after having been subjected to a deformation. Note: Test methods IUP/21.
Plate (v); plating	Mechanical finishing process used to subject the surface finish of a leather to a high pressure from a heated, polished plate or cylinder to obtain desired smoothness, flow-out, gloss and film formation.
Plated	Finished leather which has received high-gloss, smoothness or film formation by using a plating machine.
Plating marks	Marks left by the plating machine either as join marks or edge marks. Edge marks can be caused by the leather being in the incorrect condition when presented to the plating machine.
Plating press	Mechanical or hydraulic press where the leather is pressed to a heated smooth, polished steel plate.
Plump	Describes a hide or skin which is resistant to compression because the fibres have become distended by water under the influence of osmotic forces.
Plump (v); plumping	To become resistant to compression through distension of the fibres by water.
Plumping (swelling) tannage	Tanning process designed to tan pelt in a plump, or swollen, condition.
Plumping force, (swelling)	Osmotic, or other force, tending to cause collagen fibres or hide to plump or swell in an aqueous solution.
Plumpness	See: Plump.
Plush (v); plushing	Subjection of the grain surface of leather to the action of a rotating, plush-covered cylinder, or wheel, to give it a gloss. Sometimes a sheepskin covered wheel used for removing dust from the nap raising process for suedes.
Plush pad	Plush-covered pad for applying a liquid or solution evenly over the surface of leather by hand.
Pocket - (Axillae)	Part of the hide or skin which covered the hollow between the body of the animal and each limb and which, in the flayed skin, forms a loose zone between the belly area and the fore and hind shank.
Pod, (seed)	Longish fruit of certain plants, consisting of a case containing seeds. Note: Algarobilla, bablah, divi-divi, cascalote, teri.
Poisoned	Dried hides treated with an aqueous solution (0,2% to 0,3%) of arsenous oxide (dissolved with an equal weight of sodium carbonate) to prevent insect attack. After ‘poisoning’ the hides have to be dried again.
Pole dried	Air drying method by hanging the leather lengthways over a pole.
Pole dryer	Drying unit in which the leather hangs lengthways over a pole.
Polish (v); polishing	Polishing of leather by means of special polishing machines with a rotating plush covered wheel or cylinder. Stone cylinders, such as agate, are also used, heated by the contact pressure, which give the leather a glossy effect.
Polishing agent	Finishing auxiliaries containing mainly modified synthetic wax or oil emulsions to achieve a smooth, glossy surface of the leather, or used as a polishing ground for aniline or pull up finishes.
Polishing wheel	A plush-covered, rotating wheel for polishing the grain of finished leathers.
Pollution load	Quantity of emitted pollution. The parameters used to specify this pollution may be BOD5, COD, etc. See: Biochemical Oxygen Demand (BOD); Chemical Oxygen Demand (COD).
Polyacid tannage	Tannage with the iso- or hetero-polyacids of tungsten, molybdenum, vanadium or silicon.
Polyacrylates	General term for polymerisation products of the different acrylic acid esters and also copolymers, occasionally with methacrylic acid esters, as well as some monomers bearing amide groups.
Polyamide lacquer	Used as top coating agents either alone or together with nitro-cellulose lacquers. Copolymers which have obtained additional condensation with dicarboxylic acids and diamines to be soluble in mixtures of alcohols and hydrocarbons.
Polyaromatic tannin	Tannin agent whose molecule is composed of several joined aromatic nuclei; the term includes the hydrolysable and condensed vegetable tannins, as well as most artificial tannins.
Polyazo dyestuff	Dyestuff which contains several azo groups (-N=N-).
Polybutadienes	Film-forming polymer dispersions used as thermoplastic binders in finishing preparations.
Polydisperse emulsion	Emulsion which has particles in a wide range of sizes.
Polymer binder	Most important group of binders mainly used as polymer dispersions in finishing. Film-forming as well as other finishing properties depend on the monomers used, the degree of polymerisation and the varying components during copolymerisation.
Polymer dispersion	Polymer binder preparation offered by chemical suppliers as ready-to-use dispersion with a solids concentration of 30% to 60%.
Polymerisation tannage	Process of tannage involving the introduction of monomers, or low molecular weight polymers, into the pelt where they are polymerised to macro-molecules which are not necessarily combined with the collagen, such as  tannage by glyoxal or dialdehyde starch.
Polynuclear complex	Complex ion containing several central atoms, with ligands, bound to each other by linking groups, such as o, oxo, etc. groups.
Polyphosphate tannage	Process of tanning involving treatment with sodium polyphosphate in acid solution.
Polyurethane dispersion	Polyurethane binder preparation offered by chemical suppliers as water soluble one-component polyurethane dispersion. Modern top coating agents, used as well in combinations with polyacrylates, polyesters and other thermoplasts.
Polyurethane finish	Finish type using highly polymerised addition compounds on the basis of polyether or polyester polyols. The binder preparations are dissolved in organic solvents as reactive/non-reactive products or dispersed in water in crosslinking or non-crosslinking form.
Polyurethane lacquer	Finishing agents used in pigment preparations and as top coats. The products are highly polymerised polyaddition compounds of polyether or polyester polyols and of aromatic or aliphatic polyisocyanates. To be divided into reactive and non-reactive polyurethane systems. The reactive systems have to be subdivided into two-component and one-component systems.
Polyurethanes (PU)	Polyurethanes are products of an addition of disocyanates to polymeric bivalent alcohols. They are used in finishing of leather as thermoplastic and crosslinking binders. Many combinations with polyacrylates, polyesters and other thermoplasts are used depending on the desired properties of the finish coats.
Polyvinyl chloride (PVC)	Polymer substance.
Pony skin	Leather traditionally made as a hair on product from pony skins but now a hair on fashion leather made from either bovine or equine raw materials.
Pore-filling	Ability to fill the pores in a material such as leather.
Poromeric	Synthetic upper material, imitating leather, having a microporous structure, giving it water vapour