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Oak bark tannage
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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.
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Occupational Exposure Standard
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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.
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Odour
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Volatile emanations, specific
of certain bodies which may be detected by human and animal,
due to the stimulation of cells in the nose.
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OEL
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Occupational Exposure Limit.
See: Occupational Exposure Standard.
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OES
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See: Occupational Exposure Standard.
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Offal
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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.
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Offer
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To present for acceptance or
rejection; to present for sale.
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Office
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Room or department or building
used for business.
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Oil
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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.
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Oil (v); oiling. (oil off (v); oiling off)
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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.
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Oil tannage
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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.
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Oil-in-water emulsion
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Suspension of fine particles
or globules of an oil dispersed throughout water.
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Oil-waxy feel
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Leather surface that has a tacky
sensation after it has been treated with oils and waxes.
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Olation
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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.
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Old lime liquor, (stale)
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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.
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Oleophobic
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Substance which has no affinity
for, or repels, oily liquids.
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One-component polyurethane lacquer
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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.
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Ooze leather
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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.
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OP dips
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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.
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Opaque finish
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General term for all types of
finish containing covering pigments and binders.
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Open grain
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Coarser or more open
grain in contrast to a small, tight grain. Open grain leathers
are usually stretchier and of lower quality.
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Opening-up (of the hide structure)
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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.
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Optical brightener
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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.
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Orange peel
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Dappled
effect, similar to the pattern of an orange skin, caused by
too heavy spraying of the pigment finish.
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Organic pigment
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Coloured synthetic, complex organic
materials insoluble in water and in organic solvents. Used in
finish preparations as leather coating colours.
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Organic solvent
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Solvents used in finish preparations
to enhance flow-out and to obtain significant film-forming effects
by means of their evaporation rate.
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Orthopaedic leather
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Specially tanned hides or skins
for medical purposes, often using an aldehyde tannage.
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Osmotic swelling
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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.
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Overdried
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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.
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Overspraying
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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.
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Overtanned
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Containing an undesirably, or
unnecessarily, high proportion of tanning agent.
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Ox
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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.
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Oxidation
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Chemical reaction involving the
release of electrons from a substance.
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Oxidation ditch
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An oval channel with a v-shaped
cross-section fitted with rotors for aeration and circulation
of wastewater.
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Oxidation dyestuff
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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.
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Oxidative unhairing
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Removal of the hair from hides
or skins by destroying it with an oxidising agent in acid solution.
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Oxides of nitrogen (NOx)
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Oxides of nitrogen.
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Oxides of sulphur (SOx)
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Oxides of sulphur.
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Oxidisable matter
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Can be defined as (2BDO5 + COD)/3,
and is used in some countries as a basis for taxation of polluting
discharges.
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Oxidise (v) ; oxidising
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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.
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Oxolation
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The formation of a salt, the
complex ions of which contain metallic ions linked by oxygen
atoms.
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