|
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 permeability.
|
|
Post mortem
|
1. Post mortem
1a. After death
1b. Taking place, formed or done after death
1c. An autopsy to determine what caused the death
2. Postmortem: of or relating to the period
after death
(postmortem changes).
3. Post mortal: concerning death.
Note: the changes in
the cadaver.
Post mortem, postmortem, post
mortal; are of fundamental importance for the
taxidermist, hide curer, tanner.
|
|
Potlife
|
Maximum storage time of a certain
finish preparation. If the prepared solutions
are not processed within this potlife they may
loose their desired film-forming or finish properties.
|
|
Pouring head
|
Head of a curtain coating machine
regulating the flow of a liquid finish onto
the leather.
|
|
Pre-flesh (v); prefleshing
|
Removal of more or less of the
subcutaneous tissues, or flesh layer, at an
early stage.
Note: After soaking, rather than
after liming.
|
|
Preliminary tannage
|
See: Pretannage.
|
|
Premetallised dyestuff
|
Type of anionic dyestuff which
contains 1:1 or 1:2 metal complexes with metal
atoms (Fe, Cr, Cu).
|
|
Preservative
|
Chemical used to prevent microbiological
action.
|
|
Preservative pickle
|
Pickle liquor having a composition
specially adjusted to ensure preservation of
the pelts treated with it.
|
|
Preserve (v); preserving
|
To treat something in such a
way as to protect it against harmful influences.
Note: To dry or salt hides.
|
|
Pre-soak
|
Initial washing process in order
to remove dirt, dung, etc., from the hides or
skins.
|
|
Pretannage
|
Incomplete and more or less superficial
tannage of pelt with some special tanning agent
before the main tannage in order to facilitate
this.
Note: Aldehyde pretannage.
|
|
Pre-treatment
|
First stage in the treatment
process consisting of removing coarse solids,
sand, gravel and floating matter from wastewater.
See: Sand/grit removal.
|
|
Primary colour
|
One of the three colours, red,
blue and yellow, from which all other colours
in leather dyeing can be obtained by mixture.
|
|
Print (v); printing
|
Applying transfer prints to a
leather surface.
See: Emboss (v); embossing.
|
|
Print retention
|
Ability
of the grain of the leather to retain a print
pattern that has been applied by means of pressure
from an engraved plate or roller.
|
|
Printed grain
|
Artificial or simulated pattern
on the grain of the leather obtained by hydraulic
plating press or cylinder plating machines,
using steel plates or rollers engraved with
a desired grain pattern instead of the ironing
plate or roller.
|
|
Printed leather
|
Leather bearing a surface pattern
produced usually by embossing, but sometimes
by other methods. See: Embossed leather.
|
|
Protease
|
Enzyme that degrades proteins.
|
|
Protected leather
|
Leather in which certain special
chemicals have been incorporated to render it
less liable to deteriorate through exposure
to polluted atmospheres.
Note: The treatment is often
applied to vegetable tanned upholstery and bookbinding
leather.
See: Impregnated leather.
|
|
Protective lacquer
|
Finishing agent used in top coats
applied in the finishing process to protect
the leather surface from soil, moisture and
damage caused by impacts and scratching.
|
|
Protective layer
|
Top coat layer to protect the
leather surface.
|
|
Protein
|
Member of a class of high-molecular
weight, soluble or insoluble, nitrogenous compounds
forming the main constituents of protoplasm
and of animal tissues and composed of various
amino acids, joined by peptide links into one
or more inter linked polypeptide chains. Sometimes
this complex is linked to a prosthetic group.
|
|
Protein binder
|
Agents, such as blood albumen,
egg albumen or casein, used in top coats.
|
|
Protein meal
|
Protein supplement used in feedingstuffs
for livestock. Usually produced by converting
packing house (abattoir) waste and livestock
carcasses.
See: Bovine Spongiform Encephalopathy
(BSE)
|
|
Proteolysis
|
Break down of protein by enzyme
action.
|
|
PU
|
See: Polyurethanes.
|
|
Pull (v); pulling
|
Pull off the wool from sweated,
or painted, sheepskins.
|
|
Pull up effect
|
Leather has a greasy feel and
shows the pull up effect which means that on
stretching the former dark surface becomes lighter
and shows more details of the grain structure.
This is usually achieved by the application
of a special oil/grease.
|
|
Pulled wool
|
Wool removed from a sheepskin
by a fellmongering process.
|
|
Puller
|
Something
for pulling with or something which has to be
pulled, such as a cord or the slide of a zip-fastener.
|
|
Pulped hair
|
Hair removed from hides and skins
in the hair-pulping process.
|
|
Pulping
|
Reduction of the hair on hides
or skins to a mass of fine particles, or pulp,
which can be subsequently washed away.
|
|
Pure colour
|
Colour composed of monochromatic
light, not mixed.
|
|
Pure dressed
|
Leather which has been dressed
after tanning solely by the introduction of
grease, this being achieved by hand application
of dubbin.
|
|
Purple heat
|
Purple
colouration found on the flesh side of salted
hides after storage. Caused by salt tolerant
organisms that produce a purple pigment wax
that is a type of quinone. This purple colour
is destroyed by acid.
Note: Pickling.
|
|
Putrefaction
|
Hides
and skins damaged and rendered evil-smelling
by bacterial damage. See: Bacterial damage.
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PVC
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See: Polyvinyl chloride.
|
|
PVC : EC Permanent Veterinary Commission
|
EC Permanent Veterinary Commission.
|
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Pyrethrum
|
Naturally occurring contact insecticide.
Synthetic pyrethrins have also been developed.
|
|
Pyrocatechol
|
o-dihidroxybenzene, C6H4(OH)2.
|
|
Pyrogallol tannin
|
Tannin presumed to contain a
pyrogallol nucleus because it gives a blue colour
with a ferric salt or yields fragments with
a pyrogallol nucleus on alkaline fusion.
|
|
Pyrolysis
|
Thermal treatment of a material
(generally solid waste) producing gas, coke
and unburned residues under low concentration
of oxygen.
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