Haematein

Red dyestuff, formed by the oxidation of haematoxylin, which is contained as glucoside in logwood.

Hair

Keratinous fibres growing from the skin of most animals, except certain types of sheep, characterised by its stiffness, straightness and special surface pattern of scales.

Hair bulb

Lowest part of the hair inserted into the hide or skin.

See: Hair root.

Hair drying

Drying of hair recovered from the unhairing.

Hair follicle depth

The depth of the rounded sack-like structure which extends downwards into the thickness of the dermal tissue. In this narrow- mouthed follicle the hair or wool is developed and an attached sebaceous gland discharges. The follicle depth is different in various body sites.

Hair immunisation

Reduction of the solubility of hair in sulphides by means of an alkaline pre-treatment.

Hair looseness (slippiness)

Condition of the hair on a hide or skin, brought about by bacterial action or a depilatory process, such that it can be readily scraped away.

Hair loosening

Release of hair from the hide or skin.

Note: During unhairing or because of insufficient preservation.

Hair pieces

Areas with hairs left on the unhaired pelt.

Hair pore

More or less fine opening of the hair follicle on the skin surface.

See: Grain pattern.

Hair recovery

Recovery of more or less whole hairs during the unhairing process.

Hair root

Part of the hair below the grain layer.

Hair save unhairing

Any method of unhairing in which the hair is recovered more or less undamaged.

Hair screening

Elimination of whole hairs from a liquid by the means of screening.

Hair shaft

Part of the hair above the grain layer.

Hair sheep

Type of sheep having a coat of straight, stiff, fibres instead of soft and curly, and occurring in the higher, drier and more tropical regions, such as Africa, India, Java, Brazil and the Middle East.

Hair slip

Hides and skins which have undergone sufficient putrefaction to loosen the hair or wool.

Hair washing

Washing of hair removed from the unhairing.

Hair-on leather

Leather tanned without removing the original hair in the beamhouse.

Note: Textile leather such as picking band leather.

Halo

Halocarbon, halogenated hydrocarbon, hydrocarbon containing one or more halogen atoms (chlorine, fluorine) in the molecule. Note: CFC solvents.

Halotolerant bacteria

Class of bacteria that do not require salt (NaCl) for growth but can tolerate salt and are capable of growth in 20% salt environment. Halotolerant bacteria are frequently equated with halophiles, a group of archaeobacteria that require salt for growth.

Hammameli tannin

Crystalline degalloylhexose, without tanning properties, isolated from the bark of Hammamelis virginica.

Hammer (v); hammering

Process of striking repeatedly with a hand or mechanically operated hammer, to consolidate bottom leather, to flatten a welt after attachment or to shape an upper to the last.

Hand boarded

See: Board (v); boarding.

Hand buffed

See: Buff (v); buffing.

Hand grained leather

See: Board (v); boarding.

Hand stuffing

Application of grease by means of a pad or brush, to the surface of damp leather, spread upon a table.

Handle

Sensation or feeling of certain physical properties of leather, such as flexibility and smoothness, which can be perceived by touch with fingers and hands.

Handle (v); handling

Removing  hides or skins from a processing vessel or liquor   and replacing them in the same or another vessel or liquor.

Hang (v); hanging

Suspend a hide from above by means of one or more nails, hooks, strings, etc., through one end or edge.

Hang drying

Drying method of leather, generally under cover in a normal atmosphere with ventilation or with the addition of warm air.

Hard grain goat

Goatskin leather with a characteristic pinhead grain pattern, produced by hand boarding, after glazing, in a damp condition in at least four directions. Vegetable tanned.

Note: Sometimes called Morocco. In Germany also combination tanned and especially sumac tanned.

Hard resin

Synthetic resin which produces a film, inflexible and not easily penetrated.

Hardened fat

Solid fat made by chemical reaction (hydrogenation) from certain animal and vegetable oils.

Hardener

Agent in finish preparations to assist film-forming or to improve the properties of a finish by a hardening effect.

Hardness

Amount of calcium carbonate dissolved in water, usually expressed as parts of calcium carbonate per million parts of water.

Harness leather

Strong, flexible, curried, cattle hide, grain leather with a plain finish, usually having a thickness of 4 mm to 6 mm.

Hat leather

Sheep or calf leather, usually vegetable tanned, specially prepared for the sweat bands of hats or caps.

Note: Also termed "Hatband leather".

Hat leather

Type of hydraulic leather moulded in the shape of a hat.

Haul (v); hauling

Removing individually hides or leather in process from a pit.

Hazardous wastes

Waste which can cause or significantly contribute to an increase in serious irreversible incapacitating illness or pose a substantial hazard to human health or the environment because of its quantity, concentration or physical, chemical or infectious characteristics.

Health and safety instruction

Instructions for a machine or a process, intend to prevent injury to an operator.

Heat damage - (in paint)

Damage to skins caused by temperatures rising which may be due to exothermic reaction of the alkalis used, or if the paint solution is too warm when applied.

Heat pump

Device for transferring heat from a substance or space at one temperature to another substance or space at a higher temperature. It consists of a compressor, a condenser, an expansion valve, and evaporator. Is used in raw sheepskins and leather drying.

Heating up - (in paint piles)

Elevation of temperature in the middle of a pile of sheepskins that have been painted  with an aqueous depilatory mixture.

Heavy metal

Metal whose specific gravity is approximately 5.0 or higher (such as lead, copper, chromium, nickel). The heavy metals content in wastewaters is usually strictly limited by the environmental legislation as well as in final goods asking for “ecolabel”.

Note: Lead, copper, chromium, nickel.

Heel

Raised component under the rear of the shoe consisting of any of a wide variety of shapes, heights, styles and materials.

Helvetia leather

In Italy, Spain and the UK a yellow, very tough, flexible, greasy, cattle hide leather, traditionally salt and alum pre-tanned and then stuffed with a mixture of fish and animal oils. The yellow colour is caused by oxidation.

Hereford hide

Hide of a breed of a hardy red beef cattle with white faces and markings that originated in Herefordshire, England, but are now extensively raised in the Western USA and other grazing regions. The Hereford hide is carrier of a genetic peculiarity associated with pure Hereford breed; the fibres of the hide tissue are arranged in a parallel manner nearly perpendicular to the grain surface.

See: Vertical fibre; cauliflower effect.

Hide

The outer covering of a mature or fully grown animal of the larger kind.

Hide powder

Powder from an untanned or lightly chrome-tanned hide, used in the vegetable tannins analysis.

Hide powder method

Method to evaluate the tannins and non-tannins content in a liquid or a material (in solution) by measuring the amount of matter bound by the hide powder.

See: Filter bell.

Hide processor

More or less long and large diameter, rotatable drum, inclined at an angle which may be fixed or variable, with an open upper end for loading and unloading and with an internal spiral blade system; used for treating hides or skins with liquors.

Hide salt

Common salt of appropriate purity and grain size for salting hides; sometimes denatured.

Hide substance

A way to express the protein content in a leather.

Hide wringer

Machine for squeezing superfluous liquor from prefleshed, brined hides by passing between rollers. These hides are sufficiently ‘dry’ to be bundled immediately.

High frequency conditioner, dryer

Drying or conditioning unit, mainly as through-feed process. It is possible to achieve accurate moisture contents in the leather by means of electromagnetic waves with very high oscillation frequencies.

High Performance Liquid Chromatography (HPLC)

Method used in chemical laboratory to separate the chemical compounds of a chemical mixture. This separation is carried out in a liquid phase at high pressure in a column.

High Performance Liquid Chromatography – Diode Array Detector (HPLC-DAD)

Same as High Performance Liquid Chromatography, with a specific detector used to detect, for example, such products as azo dyes.

High Volume Low Pressure (HVLP)

System used in spray finishing of leather, based on a high volume of air at a low pressure feeding the spray guns.

Hippy velour

Ragged-looking patchy or mottled suede leather made from an unfleshed hide or skin, finished on the unfleshed side.

Note: Also known as "Wild suede".

HLB

See: Hydrophilic Lipophylic Balance.

Hogskin

Grain gloving leather made from the skins of the peccary and carpincho and in Germany also the domestic pig. This leather is sometimes buffed on the grain and then is known as buffed hogskin.

Hold up

Poor hold up refers to the appearance of the surface pigment finish. A patchy appearance  may be caused by excessive penetration of the base coats.

Hole

Hole caused by butchers when removing hides from the carcass. Also mechanical damage holes. Note: Fleshing machine damage.

Hoof

Hard, horny casing of the foot of certain animals such as  horses, cattle, deer, swine.

Horn

Permanent growth, often curved and pointed and usually one of a pair, on the head of cattle, sheep, goats and other mammals; it consists of a keratinous sheath over a bony core.

Horn rake

Long narrow surface lesion caused by the horns of cattle too closely herded together.

Horse butt

Rear part of a horse hide obtained by cutting from flank to flank at right angles to the backbone.

Note: A horse butt represents about one-third of the whole hide.

Horse butt

Leather made from the rear part of a horse hide.

Horse leather

Leather made from equine animals.

Hot pit (v); hotpitting

Used at the end of pit vegetable tanning. A high strength liquor (17 °Bé to 18 °Bé ) with a raised temperature of 40 °C to 43 °C which reduces  the particle size, allowing greater penetration and fixation.

Hot stuffing

Introduction of grease into leather by treating in the dry or damp state with hot, molten grease by surface application, drumming or dipping.

Hot water mark

Localised area of hide or skin affected by hot water or steam pipe where the collagen has partially or completely gelatinised.

Hot-air stuffing

Introduction of grease into leather by milling it in a damp state in a drum heated by hot air.

HPLC

See : High Performance Liquid Chromatography.

HPLC - DAD

See : High Performance Liquid Chromatography – Diode Array Detector.

Humidity

Atmospheric water vapour content expressed in any of several measures, such as relative humidity.

Humidity controller

Device for controlling the moisture content of the atmosphere in a system.

Hunting calf

Suede upper leather with the suede on the flesh side, made from a larger calf skin or from a veal.

Note: Somewhat coarser than suede calf.

Hunting suede

Suede upper leather, finished on the flesh side, made from calf skin, heavy goat or cattle hide. See Hunting calf.

Husk

Dry, outer covering of certain fruits or seeds, such as the seed pods of Teri.

Note: Caesalpinia digyna.

HVLP

See: High Volume Low Pressure.

Hyaline layer

Very thin, glass-like film, said to exist between the Malpighian layer and the grain membrane.

Hyaluronic acid

Viscous mucopolysaccharide (glycosaminoglycans) composed of acetylglycosamine and glycuronic acid units widely found in animal tissues (for instance in synorial fluid, in the ground substance of  connective tissue and in the vitreous tissue of the eye), as well as in bacterial capsules.

Hydration

Incorporation of molecular water into a complex molecule with the molecules or units of another species; the complex may be held together by relatively weak forces or may exist as a definite compound.

Hydraulic leather

Hide leather specially prepared to be flexible enough for moulding to shape.

Note: Usually supplied in the mellow rough tanned state but sometimes dressed or wax impregnated.

Also known in North America as packing leather.

Hydraulic leather

Leather items made from hydraulic leather, moulded to shape and impregnated with wax.

Hydraulic plating press

Obtain desired plating effect and film formation of finished leather by high pressure from a heated, polished steel plate.

Hydro-extractor

Centrifugal machine, with a perforated inner cage, rotating at very high speed.

Note: Used to extract water from skins.

Hydrogen Sulphide (H₂S)

Colourless gas with characteristic odour of rotten eggs, heavier than air and toxic when inhaled. In the tanning industry, the liming liquor containing sulphide is drained off and sent to the effluent treatment plant where hydrogen sulphide gas may concentrate.

Hydrolysable tannin 

Vegetable tannin of the class which, in contrast to tannins of the condensed class, can be split by enzymes (tannase), or dilute acid into simple units, (glucose and phenolcarboxylic acids), such as gallic, digallic and ellagic acids.

Hydrolysis

Decomposition or alteration of a chemical substance by water.

In aqueous solutions of electrolytes, the reactions of cations with water to produce a weak base or of anions to produce a weak acid.

Hydrometer

Device for measuring some characteristics of a liquid such as its density (weight per unit volume) or specific gravity (weight per unit volume compared with water). Hydrometers may be marked in any of  four scales: Specific gravity, Twaddle, Baumé, and Barkometer. Specific tables show the relationship between BK, Tw, Bé, and specific gravity and allow the conversion of the readings.

Hydrometer method

Method to evaluate the concentration of, for example, vegetable tanning floats, by measuring the density.

The density can be expressed in different ways.

Note: g/v, Barkometer degrees, Baumé degrees.

Hydrophilic group

Group which has affinity for water.

Hydrophilic Lipophylic Balance (HLB)

Relative simultaneous attraction of an emulsifier for two phases of an emulsion system. For example: Water and oil.

Hydrophobic group

Group which has no affinity for water, or repels water.

Hydrophobing

Rendering a material such as shoe or garment leather, water repellent.

Hydroxyproline

C₅ H₉ O₃ N. Amino acid that is essentially limited to structural proteins of the collagen type.

Hygroscopic equilibrium

Equilibrium between the moisture content of a material and the surrounding moist atmosphere.