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Unlike most manufactures, the tanner has no control over the supply or quality of his raw material. The supply of hides and skins depends on the level of meat consumption: the quality depends on the farming and abattoir. Because hides and skins are a by product and a commodity which in the internationally traded, prices are subject to very significant fluctuations,(farming and abattoir practices leading to impaired leather quality, leather trade house kings park road. Moulton park Northampton nn3 1JD.)
The raw material for leather industry is derived from the integument of higher vertebrates' particulary mammals. Generally, the hides and skins of domestics animals are used and to a less extent those of wild animals and reptiles. One of the conditions for manufacturing leather of good quality is that the hides and skins should be free from surface defects. Such defects may arise from a variety of causes (PITMAN'COMMON COOMMODITIES AND INDUSTRIE by K.J.ADOCOCK) and printed by SIR ISAAC PITMAN & SONS, LTD, LODON, BATH, and MELBOURNE AND NEW YARK.).A remarkable feature of the leather trade is the great waste due to the carless preparation of large number of hides and skins. Naturally, owing to their greatly increased value in recent years, there has been a decided improvement, but much less occurs every day from damage to hides which ought to be avoided. The chief faults are in flaying and curing, but there are other important defects due to natural causes. Bad flaying may be due (1) to cutting holes in the hides or skins(2) to "scoring "or "siding"(ice, cutting in the hide without going completely through), this generally occurring in the flanks or sides which are the most difficult parts of the hide to remove from the carcase: and (3) to miss-shaping the hide, which ought to be left square.
Primarily the defects are grouped into two major categories.
Ante mortem defects (Occurring on the living animals)
Post-mortem defects (occurring on the dead animals)
1. Congenital defects.
a.perodermiab.congenital alopeciac.congental Ichthyosisd.congenital hypertrichosise.congenital hyperpigmentationf.Congenital hypopigmentation.g.congenital hyperkeratosis
11. Defects due to metabolic disturbances:
a.calcigranulomab.Presternal calcificationc.Amyloidosisd.Xanthomatosis.e.Acquired Pigmentationf.Yellow fat diseaseg.Ceroid deposition.
111. Defects due to hypertrophy (required nature from miscellaneous causes) of the skin.
a. Hypertrophy of the skin.b.Dermatosis with hyperkeratosis and parakeratosisc.X-diseased.Coal tar diseasee.Callus (Tyloma)f Wartsh.A canthosis nigricansi.Vegetative dermatosis in swinej.Eczema.
1v.Defects arising from Hypertrophy of the skin and subcutaneous tissue
a. Elephantiasis (Pachyderm) b.Interdigital swelling in cattle
V.Defects due to circulatory disturbances
a. Hyperaemia of skin.b.Erysipelatous erythema.c.Anasarcad.d.Oedema disease of goat.e.oedema disease of pigs.f.congenital Universal hydropsg.haemorrhages on the skin. h.Gangranei.Veininess.
vi. Defects arising from inflammation due to mechanical and physic-chemical factors.
(Primary Essential dermatitis) (Secondary symptomatic dermatitis)
a. Mechanical causes.b.Chemical factors.c.Thermal. Factorsd.Parasitice.Urticaf.Burns (General or Local).g.Freezing of tissues.h.Sun burn/dermatitis Solaris.
vII. Defects arising from inflammation involving the corium (due to miscellaneous bacteria)
A.Abscess.b.Sycosis.c.Acne.d.Impetigo.e.Furunculosis.f.Phlegmon.g.Skin inflammation caused by necrosis producing bacteria.
VIII. Defects arising from specific diseases (due to specific bacterium and virus).
a. Skin tuberculosis .b.Cutaneous glanders.c.Ulcerative lymphangititis in equines.d.Ulcerative lymphangitis in cattle.e.Actinomycosis.f.Streptothricosis.g.Botryomycosis.h.Mycosis fungoideas.i. Diamond skin disease.j.Anthrax.k.Dermatitis due to bovine leptospirosis.l. Lumpy skin disease.m.Myxomatosis of rabbits.n.Nodular dermatitis.o. Infectious fibromatosis.p.Pox.q. Contagious Pustular Dermatitis/ethyma contagiosum/lip and foot scab of sheep and gooat.r. Goat Dermatitis.s. Bovine Papllomatosis.t. Foot and mouth disease.u.Vesicular exanthema of pigs.v. Rinderpest.w. Mucosal disease.x. Strawberry foot rot in sheep.y. herpes.z.Pemphigus.a.Hard pad disease.
IX. skin tumours as causative agents for defects in hides and skin.
a.Fibroma.b. Lipomas.c. Chondromas.d.Osteomas.e.Leiomyomas.f.Haemangioma.g.Lymphangioma
h.Melanomas.i.Melanosarocoma.j.Mastocytoma.k.Sarcomas.l.Sarcoids.m. Papillomas.n. Carcinomas
o. Basalomas.p. Basal cell Carcinomas.q. Sebaceous gland adenomas.r. Sweat gland adenomas
X. Defects caused by fungi (dermatomy cases)
a. Trichophytosisb. Microsporia.c. Favus.d.Balstomycosis.e.Cryptococcosis.f.Epizootic Lymphangitis
g.Cutaneous aspergillosis.h. Fungal eczemas
XI. Defects due to leucosis.
XII. Defects caused by animal parasites (dermatozoonoses)
a.Ticks.b.Lice.c.Sarcoptic mange.d.Psorcoptic mange.e.Psoroptic defect on goat skin.f.Chorioptic mange.g.Demodectic mange.h.Psoregates ovis.i.Cockle defect.j.Warble damage.k.Cutaneous myiasis.l.Streaky summer eczema of horses.m.Filarial change in the skin.n.Summer bleeding.o.Cutaneous harbronemiasis or summer sores.p.Rhabditidiasis.q.Strong
B. Post-mortem defects (caused during flying, curing storage and beam house processing)
XIII. Defects of chemical origin
a. Salt strip.b.Salt stains.d.Hard spot.e.Spew
XIV. Damage and defects due to micro-organism
(i)Defects due to bacterial action during Stalin
a .Hair slip.b.Putrefactive damage
(ii) Defects due to bacterial action during storage of salted skins.
c.Red heat.d.Wet belly
(iii) Microbial defect on tanned leathers
XV. Insects (damage due to skin beetles)
GERHARD JOHN POSSIBLE DEFECTS IN LEATHER PRODUCTION PUBLISHED IN 1996 DRUCK PARTNER RUBELMANN GMBH CARL-BENZ-STREES 11 D-69495)
RAW HIDE AND SKINS COMMONELY DEFECTS OCCUR.
1. Warble fly (Hypodermis bovis)
Larvae of the warble fly which result from the bite of the warble fly and which eat their way from inside the animal through the skin, producing open or scares holes, the so-called warble marks. Control is by mechanically removing eggs and larvae, treatment with special phosphoric esters or contact insecticides.
The defect in sheepskins known to the leather trade as cockle is first recognised after the wool has been removed from the skin. It appears at the surface as a small firm nodule which tends to run in distinct lines from backbone out towards the belly. In the region of the nodule there distinct changes in the skin.( farming and abattoir practices leading to impaired leather quality, leather trade house kings park road. Moulton park Northampton nn3 1JD.)
(LEATHER TECHNICIAN'S HAND BOOK BY J.H. SHARPHOUSE, B.SC. LEATHER PRODUCERS' ASSOCIATION KING PARK ROAD, MOULTON PARK, and NORTHAMPTON NN3) the value of a hide or skin deponed on the value of leather that can be made from it. This deponed on the current market for that Specific type of leather and, ultimately. On the market for the particular type of leather article that can can be made from it.Generally, any one of the faults or defects mentioned in earlier parts of this section is undesirable in a leather article and considerable effort is needed to avoid them, either by skin selection, selective cutting of fault free part of the leather, or processing tech niques to cover or minimise the faulty areas. Thus, if the leather article demands only small pieces, these may be cut from fault free areas but where a large piece is need, e.g. the sleeve of a coat, this demands a skin with large fault is significant but also their location. If grain leather is required, the faults on the flesh side may be of little import, whilst the reverse will be true if the leather is finished on the flesh side as suede. The following table gives some indication of the downgrading of the value of hides due to faults.
Fault %loss in value
Fault in belly 3%
Fault in butt 6%
Fault in butt and belly 10%
Butcher cuts 9%
Up to 8 open grub holes 10%
Casual, fallen hides 50%
(HIDES AND SKINS BY JOHN.R.ARNOLD PUBLISHED BY A.W.SHAW COMPANY LONDON, A.W.SHAW AND COMPANY, LIMITED) where a specific commercial classification of fallen stock is recognized it may cover many defects, of which the most important are the following:
1.Bad take -off, due to the difficulty of skinning a carcase which has lost its animal heat and which usually cannot be moved to moved to a place permitting of skilful handing .
2.Taint, which is the incipient decay resulting from exposure of a carcass to damp ground, to a hot sun, or to a moist atmosphere, when such damage is far advanced a piece of raw stock is sometimes called a murrain hide or skin.
3.Skin injuries, resulting from the dragging of the animal's body before death against stand, stones, or rough vegetation, from the the horns or hoofs of other animals during confinement in railroad cars or vessels, or as an incidental consequence of accidents occurring in such places.
Not all hides or skins of animals falling during the migration of herds or flocks on ranges, or while being driven to market, or during transportation, are characterized by these defects; but the proportion is high and the quantities marketed have at times been large.
(LEATHER MANUFACTURE: APRACTICAL HANDBOOK OF TANNING, CURRYING AND CHROME LEATHER DRESSING. ALEXANDER WATT.PUBLISHED BY LIGHTING SOURCE UK LTD.)A few years ago me. George Middleton, manager of the midland counties "Butchers" hide, skin, &, company (limited), suggested the plan of issuing cheques to slaughter men, entitling them to a reward of sixpence for each hide taken by the company flayed to its satisfication.In addition to this, the master butchers agreed to an extra sixpence per hide, as a reward for careful flaying, thus giving the slaughter men one shilling per hide for performing the their work with extra, that is proper, care.
(LEATHER FROM THE RAW MATERIAL TO THE FINISHED PRODUCT BU K.J. A DOCOCK PUBLISHED LONDON: SIR ISSAC PITMAN & SONS, LTD) several other system of improved flaying has been devised, and some of them patented. But very few have been adopted on a practical scale. One of the most useful consists of fixing a safeguard about a quarter of an inch from the edge of the knife: this prevents the possibility of cutting holes into the hide, although it does not, of cutting holes into hide , although it does not, of course, prevent scoring, which is a serious defect in hides made into sole leather. A safe method is to use a sharp knife of hard wood, such as hickory, which has been successfully tried in one of the large American meat-packing establishments. The hides from these abattoirs are generally well-flayed, properly cured, and closely trimmed, with the result that they command higher prices than any other class of salted hides. The quotations for "packer" hides are followed with keen interest by tanners in all parts of the world. Another useful method of preventing damage to the hides by cuts with a knife is that invented by Mr. E.Pim, a Liverpool hide factor. The apparatus used is known as the tail extractor. It is of simple construction, consisting of four pieces of iron riveted together loosely in the shape of diamond with a clamp attached to secure the tail. The hide is then forcibly removed from the tail and the buttocks by pulling it downward (fig)
The importance of this operation can be gauged from the fact that by the use of the butcher's knife both of these parts of the hide are often cut very badly. Even the apparently trivial matter of removing the hide from the cheeks and face is economically important, for unless those parts are removed so as to get the maximum surface , they are only fit to be cut off and thrown in a pit with other pieces and rounding's which are made into glue.(SCIENCE FOR STUDENTS O F LEATHER TECHNOLOGY BY VOLUME EDITOR:R. REED, M.SC, PH.D PUBLISH PERGAMON PRESS OXFORD, LONDON, EDINBURGH.)Several species of flies, notably the larger Tabanids (horse -flies) bite (i.e. Puncture) and suck blood from the living animal. Cattle also, particulary in tropical regions, often carry a large population of ticks capable of puncturing skin. These wounds may at first be small and appear negligible, but they are very susceptible to bacterial attack. Often bacteria are introduced by non-biting flies which swarm round the open wound. Damage of this kind may very from minute holes ("stung" or "pin-hole" hides) to large clearly visible holes classified as bacterial. After healing, scar tissue will remain giving rise to grain irregularities which are often emphasized by the operations carried out in the tannery and dyhouse.
Conclusions (.(SCIENCE FOR STUDENTS O F LEATHER TECHNOLOGY BY VOLUME EDITOR:R. REED, M.SC, PH.D PUBLISH PERGAMON PRESS OXFORD, LONDON, EDINBURGH.
Most skins, particulary those which are dried, spend much time in various stores, not all of which may be adequately supervised,e.g sheds at the dock and the holds of ships. Infestation may be from adjacent stored goods and by the time the goods reach the tannery and are inspected, a large population may have developed and the damage may be devastating. Such infestation can also be transferred unwittingly to the tannery hide store by the incautious opening of baled goods. Hair and wool-skins are sometimes infested with larvae of clothes moths including several species of the family Tineidae: most of the damage done by these insects is to the hair, which may be stripped from whole areas. In such cases the epidermis is almost invariably damaged also, giving an inferior grain. Provided that the relative humidity is high enough for their needs. Clothes moths can continue to breed in the bale and several generations may be present at the same time, hence causing widespread damage. Larvae may often be found in tunnels loosely constructed from hairs whilst pupae usually lie within a whitish silken cocoon similarly situated.