Читать книгу Leather: From the Raw Material to the Finished Product - K. J. Adcock - Страница 4

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The hides and skins of animals form the principal raw material of the tanner. Technically, the term "hides" is applied to the skins of the larger animals, while the word "skins" is used in the case of the smaller animals. Thus, the tanner speaks of ox, cow, bull and horse hides, and of calf, sheep, and goat skins. There is an intermediate size between a full-grown calf skin and a small hide, and this is known as a "kip," but the line of demarcation is not very clear.

Buyers often settle the difficulty by examining the growth marks and the irregular substance of the skin, and, if these are marked features, it is classified as a kip. The condition of the hides of cattle is usually inferior during the six months after the animal has become a yearling. East India tanned hides, which are largely imported into England, are frequently described as E.I. "kips" in the trade. This is hardly accurate, but the mistake is probably due to the small size of full-grown Indian hides, which are very little larger than the average European kips. It is interesting to observe that furriers always refer to both their raw material and the finished product as skins, irrespective of the size of the fur-bearing animals. Most of the skins of wild animals are dressed without removing the hair or fur, and this is quite a distinct trade from leather manufacture, the only exception being the dressing of closely cut and fine-haired calf skins for slippers and fancy articles.

Practically every country in the world contributes to the supply of hides and skins, but there are a few countries which are far in advance of the others in the industries of cattle and sheep-raising. The sources of tanners' raw material have undergone great changes since the establishment of freezing and chilling stores for the preparation of meat for export, and the market prices of hides are to a large extent controlled by the supply in North and South America, South Africa, and Australia. Whether or not the concentration of these huge meat works into two or three centres is likely to benefit the leather trade is a debatable point. The flaying, trimming, and curing of hides in these establishments are certainly superior to the work done by the average butcher, while, owing to the large numbers of cattle slaughtered, the hides can be closely selected. On the other hand, the value of hides and skins has risen enormously in the last decade, the period coincident with the rapid growth of the chilled and frozen meat industry, but the increased use of leather in many directions may be mainly responsible for the higher cost of the raw material, although it is obvious that the concentration of the chief supplies of hides in a few lands must tend to increase the severity of the competition among buyers. Apart from the high prices of the hides, the concentration of the meat industry in large chilling and freezing works has had the effect of increasing the prices of beef and mutton, which are now higher in price than freshly-killed English meat was a few years ago. It appears to have been a grave error on the part of the British Government when they stopped the imports of live cattle owing to the fear of foot-and-mouth disease being communicated to domestic herds. The disease has broken out in several places since the embargo was imposed, so that the theory that the infection was only carried by imported live cattle has been clearly disproved. The butchering of cattle provides a large amount of work in subsidiary industries, and the Government embargo on the importation of live cattle has caused a great deal of distress in Deptford and Birkenhead, where large abattoirs were erected for the reception of live cattle, which used to be imported in fairly large numbers. There is no danger of foot-and-mouth disease getting beyond the abattoirs or of the slaughter of diseased cattle for food, and both tanners and butchers hope to see the removal of the embargo. So far as possible, each country should raise its own cattle to provide its own meat supply, and this principle is recognised by many countries which prohibit the import of foreign meat: but, owing to the rapid growth of populations in industrial countries, with the consequent increase in the value of land, it has become impracticable to raise enough cattle to supply domestic needs. Even the United States of America, which formerly had a great cattle-raising industry, has lately been obliged to import live cattle to meet the requirements of its inhabitants. Similar conditions prevail almost throughout Europe, and tanners have to look to South America, Australia, and Africa for large supplies of raw hides, although there are still some tanners in the United Kingdom who use only the hides produced in this country.

The bulk of the production of hides and skins in the United Kingdom is disposed of at weekly public auctions in the principal towns: London, Manchester, Liverpool, Leeds, Birmingham, Newcastle, and Glasgow being the largest centres of distribution. However, there is still a large quantity bought by private treaty, and opinions are divided as to which is the better method of buying. Before the establishment of public auctions, hides were very cheap, but tanners were unable to get a good selection, although, for sole leather, that was not a very important matter. Public auctions have become so firmly established that it would be impossible for tanners to revert to the old system even if they desired it. The competition of private buyers with the auction markets has certainly benefited the butcher at the expense of the tanner, and the weighing and classification of hides ultimately became so irregular in many markets that the Tanners' Federation of the United Kingdom had to take strong action not long ago to protect their interests. They demanded the appointment of an independent inspector at each market to check the weighing and sorting of the hides, but this was successfully resisted by the market proprietors, who eventually agreed to the tanners appointing travelling inspectors to visit the markets periodically. The system is said to have improved matters.

The English markets do not collect enough hides to permit their close sorting, so that, while the hides are graded according to weight and quality and the sex of the animal, the question of varying substances is generally ignored. There is usually a difference of 10 lb. in each class where the hides are sorted by weight Ox, cow, heifer, and bull hides are sold separately, as each sort has a different value. Bull hides are comparatively poor in quality, owing to their irregular substance and strong growth marks in the neck. Ox hides are the most suitable for sole leather and belting, while cows' and heifers' are used mainly for dressing hides, which are finished into bag, case, strap, and boot leathers. The hides known as Scotch and Hereford runts are the best of those produced in the United Kingdom, as they are well-grown, compact, and well-suited to the making of sole leather and belting. The grading of the weight of these hides at the auction markets is generally as follows: 100 lb. and above, 90-99 lb., 80-89 lb., 70-79 lb., 60-69 lb., 59 lb. and less. This does not give an ideal classification, as hides vary so much in texture and substance, and it is quite possible to find spready hides of poor substance and quality which would be heavier than a small but compact and well-grown hide. It would be better from the tanner's point of view if the hides were selected according to substance and quality. There are not many bull hides grown in the United Kingdom, and in many markets they are not classed by weight but simply into best and secondary qualities. Horse hides are of even less value than those of bulls, owing to their weaker texture and irregular substance. That part of the skin under the mane is almost worthless, while the flanks and sides are only useful for a secondary class of boot upper leather, although some fairly good patent sides have lately been produced from horse hide, which is suitable for that purpose owing to its soft grain and pliable texture when tanned. The most valuable part of a horse hide is the butt, which consists of the part known as the "shell." This shell is covered with an extremely fine grain which is not found in any other part of the hide. The well-known crup leather is made from the shell of the horse hide.

In addition to hides, there are fairly large quantities of calf and sheep skins sold at the weekly auctions, but veal is not such an important article of food in England as it is on the Continent. Sheep skins are far more numerous, as Great Britain is a big mutton-consuming country. Home supplies of both hides and skins have been greatly reduced, however, by the immense import of frozen and chilled meat.

Although the domestic supply of hides and skins is quite inadequate to meet the needs of British tanners, a large proportion is exported. American tanners buy large quantities of the best hides and pickled sheep skins. The latter are dewoolled and preserved by a process of pickling with formic or sulphuric acid and salt before exportation. Those preliminary operations are the work of the fellmonger. Nearly all of the horse hides produced in the United Kingdom are, or were before the War, sent to Germany, and British leather-dressers appear to have lost the art of finishing horse hide, or are unable to convert it into leather profitably.

The interchange of raw hides between various countries, and even between those where leather manufacture is an important industry, is somewhat remarkable, and only goes to prove that the concentration of a particular industry in one or two centres of the world gives these places a great advantage in regard to labour, organisation, and technical skill, even over those countries where the raw material is plentiful. Theoretically and economically it should be advantageous to establish tanneries close to the supply of raw hides, since the latter, under present conditions of preservation, steadily deteriorate from the time they are removed from the carcase until they reach the tannery. In some countries the methods of preserving hides are actually so bad that the hides have often lost half of their value before the tanner gets them. Two or three of the largest American meat-packing establishments have erected or taken over tanneries to deal with raw hides, one of their by-products. Tanneries have also been erected near some of the large meat works in the Argentine, but the development of the leather trade there is by no means rapid, and at present the United States of America is the largest leather-producing country in the world. Germany, France, and the United Kingdom come next in the order named.

South Africa is an important source of supply of raw material, and large quantities of Cape hides are sent to England. The production of raw hides there is likely to be on a very large scale in a few years' time, as the raising of Afrikander and other breeds of cattle is sure to become an important industry now that the ravages of the terrible disease, known as "tick," have been checked. China is another large hide-exporting country; most of the hides from this source are dried in the open air and are generally arsenicated to prevent the ravages of insects. Immense quantities are also provided in all other populous countries, but the demand for leather is generally greater than the production of raw material in those countries. India is a noteworthy exception to this general rule; the production of Indian hides is enormous, and, although the leather trade is being developed, there is a large surplus of raw hides and skins for export. Large quantities are roughly tanned, however, and exported to England, Germany, France, and other European countries to be dressed and finished. The greater proportion of these hides and skins is used for the making of shoe leather, while a good quantity is used for bag (hide) and imitation morocco (goat) leathers.

Naturally, there is in the aggregate a considerable supply of raw hides and skins from other parts of the world in addition to that from the countries specially named, and new sources are being frequently found.

It would be impossible to describe the characteristics of the numerous varieties of hides and skins except in a full-sized text-book, but a brief description of the principal sorts may be given.

Some of the varieties produced in the United Kingdom have already been described. In the main, there is not a great deal of difference in the hides of various breeds, but there is a type of well-grown and stout hides specially suitable for sole and belting leather; this class is known as runts, and these hides are obtained from the Scotch and Hereford breeds of cattle. The Scotch runts from the Highland cattle are more valuable than any other class of hide found in the United Kingdom; unfortunately, the production is small. Irish cattle also yield good hides, but in England the interests of the cattle owner, or feeder, are in conflict with those of the tanner, for the system of artificially fattening cattle with oil cakes tends to make the hides very greasy and weaker in the fibres than those hides from animals which are reared on natural food-stuffs.

This grease is very difficult to remove and reduces the selling value of sole leather by about 2d. per lb. The use of a borax solution for soaking partially removes the grease, while it has been proposed that the pelts should be treated with a solution of hyposulphite of soda just before placing them in the tan liquors. A drawback of the latter process is that a little weight is lost in the finished leather.

The trouble caused by the presence of a large quantity of natural grease is even more pronounced in sheep skins than in cattle hides. Naturally, a sheep arrives at maturity in about two years; but by the modern system of intensive feeding with oily food-stuffs it can be fattened in about ten months. This is obviously a great advantage to the sheep-breeder; in other respects it is an unsatisfactory method, for the mutton is not so well matured, and, therefore, is not so nourishing; it contains too large a proportion of fat, and the skins are very greasy and weak in fibre. The excess of grease does not detract from the value of the wool, and may even be beneficial.

There are several varieties of sheep in the United Kingdom, with widely different characteristics. A fellmonger should have a good knowledge of the skins of various breeds in order to buy the particular sorts that will meet the requirements of his customers, as his business is to separate the wool from the skins and to supply the former to the woollen factories and the latter to the leather-dressers. He has, therefore, to study carefully both the wool and pelt markets. While some breeds of sheep yield fine long wool of bright lustre, others have comparatively short-stapled, and "kempy" wool. Between these two classes, there are numerous grades, and the task of sorting the various qualities of wool in those fellmongeries where several classes of skins are worked is by no means easy. It is a generally accepted axiom that the pelt (i.e., the skin denuded of wool) is weaker in fibre in those skins which yield the finest and best wool. In support of this, the Welsh mountain sheep may be cited. This sheep has short, curly wool, but its skin is tough and strong on the grain. In fact, it is about the only breed suitable for roller leather, which is used in the cotton industry for covering the drawing rollers of spinning-machines. Most of this leather is made in North Wales, whence it is exported to every country where the cotton industry is carried on.

Notable exceptions of the general rule regarding the relative qualities of wool and pelts are found in two or three English varieties, namely: the Lincolns, Leicesters and black-faced Suffolks, which produce both fine wool and large pelts of good quality.

Other useful British breeds are the Southdowns, Devons, Shropshires, Wensleydales, Scotch black-faced, Cotswolds, and Kerrys. Of the imported varieties, the New Zealand and Cape sheep skins are the best. The former, principally merino stock, not only provide very fine wool, but also pelts of choice quality and large pattern. Although the quality of the wool of Australian merino sheep is little, if any, inferior to that of the New Zealand type, the skins are not so good in quality, due, no doubt, to the hotter climate, which is favourable to the breeding of insects and other pests which damage the skins. The Cape sheep provide a skin which is quite different in texture from that of any other breed. It has a certain looseness of texture and softness of grain which make it particularly suitable for the manufacture of glove leather.

South America is another large sheep-breeding country; but the skins of this variety are not largely imported into England, most of them being sent to Mazamet, the great centre of the fellmongering industry in France. Buenos Aires skins are the most favoured of the South American skins, owing to their large size and good substance. Monte Videos are also very fine skins.

Smyrnas and Bagdads are other well-known varieties, but they are generally imported in a rough-tanned condition, or, as it is known technically, "in the crust." Leather-dressers finish them for various purposes, but mainly for boot and shoe lining leather. When properly tanned by the natives, these skins produce a supple finish, especially those of the Smyrna variety. Unfortunately, many lots are merely coloured on the surface with the tan liquor, with the result that they dry hard and tinny; such partially-tanned leather is very difficult to finish and is rarely satisfactory. Even when the tannage is completed elsewhere before finishing them, they never produce such good leather as skins properly tanned in the first instance.

Russia is another important country for the production of all kinds of raw hides and skins suitable for leather manufacture. American tanners buy very largely from this market, and a few enterprising firms even send their own representatives to the great annual fair held at Nishni Novgorod, where large quantities of dried hides and skins, besides many other kinds of produce, are offered for sale. British tanners take comparatively little interest in this important supply, but, as a result of the great European War, an increase of trade between Russia and the United Kingdom is anticipated, although the Russian leather trade is developing rapidly and will absorb increasing quantities of native raw material.

Excepting a few in Ireland, raw goat skins are not produced in Great Britain. The chief drawback to goat breeding there is a somewhat inexplicable aversion on the part of the public to the flesh of goats; although another reason may be the destructive nature of the animals themselves, for they devour and uproot anything edible that comes in their way. It is, perhaps, unfortunate that some of the large areas of uncultivated land in Great Britain are not given up to the breeding of goats on a large scale, since these hardy animals will thrive on rough, hilly lands. Apart from the value of the meat, it might be a paying proposition to rear large herds of goats for the supply of milk (which is more nourishing than cows') and skins. Leather-dressers are, therefore, dependent on imported supplies, of which the principal sources are India (North-Western District), Mexico, Arabia, Africa, South America, and several European countries.

Goat skins from the main sources of supply vary very much in quality—even those produced in the same country. In India, for example, skins may be obtained in some districts which can be made into leather to sell at about 5d. per square foot; from another district, when finished into the same kind of leather, say glazed kid, they may be worth 1s. 4d.[1] per foot. Fineness and clearness of grain and good substance are the main essentials of a first-class goat-skin leather; unfortunately these qualities are rarely combined in one class of skin, and there is a decided surplus of light thin skins which are hardly saleable, even for ladies' shoes. Some American shoemakers overcome this difficulty by pasting a piece of cloth on the back of the skin. In fairness to the buyer, the boots made of such leather should be specially marked, as the wearing quality of a backed thin leather is not to be compared with one naturally stout.

[1] It must be understood that, owing to the war, these prices have been greatly increased.

The skins of goats are used for many purposes besides the manufacture of the famous glacé kid leather; gloves, moroccos for bookbinding, upholstery for furniture, fancy articles such as purses, pocket-books, bags, and ladies' belts all require large quantities of goat and kid skins. It may be pointed out here, however, that quite nine-tenths of the so-called kid gloves are made of lamb and sheep skins. In appearance, there is very little difference between the real kid and the lamb skin gloves, but the former are more durable and warmer in wear than the latter.

With an enormous range of qualities, it is a difficult task for the goat-skin dresser to find the most suitable sorts for his trade. The skins used in the glove industry are largely obtained from the Near Eastern countries, Arabia, Austria, Spain, and the Cape. The selections best suited to the making of glazed and "patent" (japanned) kid are found in the North-Western provinces of India, Brazil, China, Russia (especially the Asiatic provinces), Mexico, the Cape, and Arabia. The Indian goats known as the Patnas, which are collected in the district of Behar, are commonly supposed to be the best in the world, chiefly because of their fine grain and stout substance; but the best Brazilian and Mexican skins are equally good in quality. The best moroccos for fancy articles are made from Continental skins, and in this respect Germany has the great advantage of a good supply of native skins. Norway and Spain also provide skins suitable for real morocco leather. A very large quantity of Indian-tanned goat skins are imported into European countries and dressed for "morocco" leather. There should be a distinctive name for this class of leather, as, although it is similar in appearance, it is not nearly so good in quality as the real morocco.

In addition to cattle hides, sheep, and goat skins, which are the main supply of raw material for leather, other kinds of hides and skins are utilised. Horse hides, which, in the United Kingdom, are graded according to size and quality in four or five selections and sold by the piece, are largely used on the Continent, and especially in Germany; nearly all of the British production being sold to that country. When chrome tanned, these hides produce quite a serviceable upper leather of good wearing quality, but, owing to their somewhat loose texture, the characteristic grain of box calf cannot be reproduced naturally, and the surface of the leather has, therefore, to be printed. This style of finished leather does not meet with the favour of British boot manufacturers, and the industry has not been greatly developed in consequence. In view of the increasing cost of other kinds of leather, however, more attention may be paid to that made from horse hide, but the supply of this raw material is very small compared to the production on the Continent, where horse flesh is consumed freely. Russia produces large quantities of horse hides and colt skins, most of which are exported to the United States of America, where they are made chiefly into japanned, or so-called "patent," leather, which commands a very high price in relation to the cost of the raw material.

Next in importance to horse hides is the pig skin, which produces a wonderfully tough leather. The pig skin leather industry is chiefly confined to Scotland and Germany, the reason being that the skins are left on the carcases in the other parts of the world. On the average, a pig skin is worth about 6s., yet it is seldom removed from the carcase. One reason is the great difficulty of flaying the animal; it appears to be almost impossible by present methods to remove the skin without cutting away a large quantity of fat, and the value of the skin compared to the loss of weight of the meat offers very little inducement to remove the skin, in addition to which, the custom of leaving the rind on bacon and pork effectually prevents any attempt at present to increase the supply of pig skins. This is a great loss to the leather trade, for the pig skin is particularly suitable for saddles and various kinds of strong leather goods. Imitation pig-skin leather is made from hides, shoulders, bellies, or persians, but real pig skin is distinguished from the imitation by its peculiarly marked grain, formed of groups of three small holes which penetrate well into the skin and form part of the sheaths of the pig's bristles.

Among other skins useful for leather are those of the wallaby, kangaroo, dog, lizard, crocodile, alligator, ichneumon, frog (Japanese), deer, antelope, and chamois, while it is said that even rabbit skins have been pressed into service in Germany, though they cannot have much value owing to their small size and thin substance. Dog-skin leather wears well, mainly on account of the large amount of natural grease present in the skin, but the supplies are naturally small. The hides of the walrus, elephant, rhinoceros, hippopotamus, and other wild animals are also tanned in small quantities, walrus leather being well adapted for knife and sword polishing.

The mammals also contribute their quota to the supply of raw material of the leather trade, the seal perhaps, being the most important. This refers to the hairy seal hunted off the North American coast.

The raw skins are shipped chiefly from Newfoundland, where the industry of seal fishing is well organised and provides employment for about 6,000 men. The seal caught in the North Atlantic Ocean is hairy and quite distinct from the fur seal captured in the Arctic Ocean off Alaska. The skin of the hair seal is only suitable for making into leather, but there is a layer of fat underneath it which furnishes a valuable raw material for the manufacture of oils and soap. The skins are salted and shipped to America and England. They are easily distinguished from other kinds of commercial hides and skins by the oily appearance of the flesh side.

According to an American Consular Report, the results of the fishing during the season 1913 were satisfactory. The total number of seals captured was 272,965, which were valued at £98,800. The number of skins exported was 212,285, valued at £64,300, of which the United States of America bought 151,355, the United Kingdom 60,754, and Canada 176.

The porpoise, or sea hog, has a very useful hide which, when dressed, makes a tough leather suitable for laces. The hides of other cetaceous mammals, such as the whale and narwhal, are convertible into useful leather. The British "porpoise" laces are generally made from the skin of the white whale (beluga).

Defects of Raw Hides and Skins

A remarkable feature of the leather trade is the great waste due to the careless preparation of a large number of hides and skins. Naturally, owing to their greatly increased value in recent years, there has been a decided improvement, but much loss 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" (i.e., cutting into 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 mis-shaping the hide, which ought to be left square.

Any or all of these defects may be found in a single hide. Despite the active work of several proprietors of hide markets and the tanners' federations the proportion of badly-flayed hides in England constitutes a serious loss, which, however, may not fall directly on either the butcher or the tanner, for the former may save in wages by employing an inexperienced slaughterman, while the tanner pays a reduced price for the hide.

The losses due to bad flaying and curing in the United Kingdom are mainly attributable to the butchers' preference to kill these beasts in their own back-yard rather than in a public abattoir. Many of these small private slaughterhouses ought to be condemned by the authorities; but very few people outside those immediately interested have taken the trouble to inspect a modern public abattoir where everything is provided to carry on the work expeditiously and hygienically. On the Continent, where the conservatism of traders is not permitted to interfere with the public welfare to such an extent as it is in England, public abattoirs have become quite a feature in many cities, and one of the principal results of the system has been a remarkable improvement in the preparation of raw hides and skins for the tanner. In fact, a mechanical method of flaying has been invented in Paris, and is used extensively at the public abattoirs, by which hides are removed from cattle without a single mark or scratch. The method is known as dépouille mécanique (mechanical flaying) and consists in forcibly removing, by means of a windlass worked by electric power, the portions of hide which adhere firmly to the carcase and which are found over the ribs, the buttocks, and the tail. The remaining part of the hide can be easily removed with the ordinary butchers' flaying knife or with a heavy hammer of special design. The apparatus required to carry out the mechanical method of flaying, beyond the fixtures in the abattoirs where the process is adopted, consist of two lengths of chain to hold the carcase firmly, two special hammers, and one pair of strong pincers; the cost of one set is about £4. Mr. Gaston Tainturier, of Paris, is the inventor of this system, which has added thousands of pounds to the incomes of Parisian butchers.

Figure 1 is from a photograph taken at the Islington (London) Abattoir, where a demonstration of the process was given by Mr. Tainturier in February, 1913.

Naturally, this method cannot be adopted in small slaughterhouses in back-yards, but is readily adaptable to public abattoirs, where practically all of the heavy work is done by electrical power. This exemplifies only one of several advantages of modern abattoirs over private slaughterhouses.

Although it cannot be expected that the English butchers will readily change their prejudice against modern abattoirs, they are slowly but gradually improving the flaying process in view of the high prices paid for perfect hides. The most progressive of the proprietors of the English hide markets are offering money prizes to slaughtermen for the best flayed hides. Strictly speaking, this encouragement should come from the butcher, who receives the benefit of increased prices for hides removed without a scratch. The Tainturier system, however, gives better results, no matter how well the hides are removed with the knife. The method is not patented, and it is open to anyone to adopt it merely for the cost of the apparatus, yet, despite this gain, no butcher outside France and Belgium has yet adopted the method, although the trade is losing hundreds of pounds every week through bad flaying.

Several other systems of improved flaying have 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 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.