IULTCS Glossary Results O

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Oak bark tannage	Slow vegetable tanning process for sole leather, carried out in pits, using oak bark as the basic material and not involving hot-pitting or bleaching.
Occupational Exposure Standard	Concentration of an airborne substance, averaged over a reference period, at which, according to current knowledge, there is no evidence that it is likely to be injurious to employees if they are exposed by inhalation, day after day, to that concentration.
Odour	Volatile emanations, specific of certain bodies which may be detected by human and animal, due to the stimulation of cells in the nose.
OEL	Occupational Exposure Limit. See: Occupational Exposure Standard.
OES	See: Occupational Exposure Standard.
Offal	1. Solid wastes and by-products from hides and skins, for instance, hair, horns, raw hide trimmings. 2. Parts of hides not used for standard grades of sole leathers; the heads, shoulders, and bellies of heavy leather.
Offer	To present for acceptance or rejection; to present for sale.
Office	Room or department or building used for business.
Oil	Any of various greasy, combustible liquid substances obtained from animal, vegetable and mineral matter. A natural, or artificially prepared substance, viscous, liquid at 30 ºC, insoluble in water, soluble in solvents such as ether and benzene. Organic substance usually consisting of hydrocarbons or esters of glycerol or higher monohydric alcohols and introduced into leather for lubrication and other purposes.
Oil (v); oiling. (oil off (v); oiling off)	Apply a thin film of oil to the leather grain, to prevent oxidation during drying and ensure an elastic grain. See: Grain oil; grain oiling.
Oil tannage	Tannage by means of certain unsaturated fish or marine animal oils which, in contact with the pelt, undergo oxidation and other chemical changes, leading to irreversible fixation of various fatty derivatives.
Oil-in-water emulsion	Suspension of fine particles or globules of an oil dispersed throughout water.
Oil-waxy feel	Leather surface that has a tacky sensation after it has been treated with oils and waxes.
Olation	Condensation of hydroxyl complexes to larger ones by the union of metal ions by O bridges between them, favoured by heating. The degree of olation is the proportion of olated hydroxyl groups to the theoretically possible total amount of hydroxyl groups per chromium atom. The higher the degree of olation, the higher the stability of chrome solutions to acid.
Old lime liquor, (stale)	Lime liquor through which very many packs of hides and skins have passed, which contains notably amounts of ammonia and protein decomposition products in which bacterial action may occur.
Oleophobic	Substance which has no affinity for, or repels, oily liquids.
One-component polyurethane lacquer	Solvent-soluble lacquer with highly polymerised polyaddition compounds used in finish systems to achieve desired properties. Often used as non-reactive one-component system directly applied to the leather surface, causing crosslinking reaction with moisture in the leather, or in the air, or the amino groups of the leather substance.
Ooze leather	Vegetable or chrome tanned skin of bovine origin, generally calf, with a very soft glove-like feel and a natural grain sometimes accentuated by boarding.
OP dips	Liquid containing an emulsified organophosphorus compound into which sheep or cattle are dipped for treatment; especially for killing ticks on sheep or lice on cattle.
Opaque finish	General term for all types of finish containing covering pigments and binders.
Open grain	Coarser or more open grain in contrast to a small, tight grain. Open grain leathers are usually stretchier and of lower quality.
Opening-up (of the hide structure)	Loosening of the corium structural network and of the fibre bundles and fibres and a chemical modification of the collagen, without actual rupture of the polypeptide chains, produced during liming and by the alkaline or acid pre-treatment of collagen or ossein to render it suitable for melting-out for gelatin manufacture.
Optical brightener	Agent used to improve the white effect in the finish of white leather. By conversion of invisible short-wave light into visible long-wave light the white light reaching the eye increases.
Orange peel	Dappled effect, similar to the pattern of an orange skin, caused by too heavy spraying of the pigment finish.
Organic pigment	Coloured synthetic, complex organic materials insoluble in water and in organic solvents. Used in finish preparations as leather coating colours.
Organic solvent	Solvents used in finish preparations to enhance flow-out and to obtain significant film-forming effects by means of their evaporation rate.
Orthopaedic leather	Specially tanned hides or skins for medical purposes, often using an aldehyde tannage.
Osmotic swelling	Uptake of water by, and swelling of, a protein, occurring in acid and alkaline solutions and associated with the strongly ionic protein groups, leading to an uneven distribution of freely moving ions within and without the protein.
Overdried	Excessively dehydrated ‘hard’ dried hides or skins as a result of the hot climate (high air temperature, absence of wind), or drying under direct sunshine (sunburn), or the hot air used for quick drying of sheepskins.
Overspraying	During the application of finishes by hand or automatic sprayings, as much as 40% to 60% of material may be wasted by spray guns continuing to spray after they have passed over the leather.
Overtanned	Containing an undesirably, or unnecessarily, high proportion of tanning agent.
Ox	Large cloven hoofed, frequently horned, ruminant mammal, long domesticated for its milk, meat and hide, and as a draught animal; a castrated adult male of this animal, a steer; in plural, cattle. Note: Bos taurus.
Oxidation	Chemical reaction involving the release of electrons from a substance.
Oxidation ditch	An oval channel with a v-shaped cross-section fitted with rotors for aeration and circulation of wastewater.
Oxidation dyestuff	Dyestuff (organic base) formed in a material by oxidation of a previously applied primary product. This produces intensely coloured insoluble compounds for colouring hair or fur. If this oxidation takes place in the presence of a mordant, even deeper coloured compounds are produced and a larger variety of colours becomes possible.
Oxidative unhairing	Removal of the hair from hides or skins by destroying it with an oxidising agent in acid solution.
Oxides of nitrogen (NOx)	Oxides of nitrogen.
Oxides of sulphur (SOx)	Oxides of sulphur.
Oxidisable matter	Can be defined as (2BDO5 + COD)/3, and is used in some countries as a basis for taxation of polluting discharges.
Oxidise (v) ; oxidising	Combine with oxygen to form an oxide or oxygen compound. Increases the intensity of the reaction in the event of a fire and also results in the fire spreading very fast. It can react very violently with other stored dangerous substances including packing material and thus trigger spontaneous fire.
Oxolation	The formation of a salt, the complex ions of which contain metallic ions linked by oxygen atoms.

General term for all types of finish containing covering pigments and binders.

Agent used to improve the white effect in the finish of white leather. By conversion of invisible short-wave light into visible long-wave light the white light reaching the eye increases.

Coloured synthetic, complex organic materials insoluble in water and in organic solvents. Used in finish preparations as leather coating colours.

Solvents used in finish preparations to enhance flow-out and to obtain significant film-forming effects by means of their evaporation rate.

During the application of finishes by hand or automatic sprayings, as much as 40% to 60% of material may be wasted by spray guns continuing to spray after they have passed over the leather.