Materials Science in Light Industry Production (Материаловедение в производстве изделий легкой промышленности). Учебное пособие

or buffed on the grain side, or outside, to give a slight nap of short protein fibres, producing a velvet-like surface.

There are two other descriptions of leather commonly used in specialty products, such as briefcases, wallets, and luggage.

Belting leather is full-grain leather that was originally used in driving pulley belts and other machinery. It is often found on the surface of briefcases, portfolios, and wallets, and can be identified by its thick, firm feel and smooth finish. Belting leather is the only kind of leather used in luxury products that can retain its shape without the need for a separate frame; it is generally a heavy-weight of fullgrain, vegetable-tanned leather.

Nappa leather is chrome-tanned and is extremely soft and supple and is commonly found in higher quality wallets, toiletry kits, and other personal leather goods.

The following are not “true” leathers, but contain leather material. Depending on jurisdiction, they may still be labeled as "genuine leather."

Bonded leather , or "reconstituted leather", is not really a true leather but a man-made material composed of 90% to 100% leather fibres (often scrap from leather tanneries or leather workshops) bonded together with latex binders to create a look and feel similar to that of 'true' leather at a fraction of the cost. Bonded leather is not as durable as other leathers, and is recommended for use only if the product will be used infrequently. One example of bonded leather use is in Bible covers. Bicast leather is a man-made product that consists of a thick layer of polyurethane applied to a substrate of low-grade or reconstituted leather. Most of the strength of bicast leather comes from the polyurethane coating. Bicast was originally made for the shoe industry and recently was adopted by the furniture industry. The original formula created by Bayer was fairly strong, but expensive. Most of the bicast used today is created using inferior generic chemicals resulting in an inferior material. The result is a much stiffer product that tends to de-laminate, resulting in bubbles and cracking. The vast majority of leather is sold according to its area. The leather is placed through pin-wheel or electronic measuring machines and its surface area is determined. The unit of

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measurement is square meter, square decimeter or square foot. The thickness is also important, and this is measured using a thickness gauge (the unit of measurement is millimeters, e.g., 1.8 mm is a standard thickness for a school shoe).

In some parts of the world, top-grain thicknesses are described using weight units of ounces. Although the statement is in ounces only, it is an abbreviation of ounces per square foot. The thickness value can be obtained by the conversion: 1 oz/ft² = 1/64 inch (0.4 mm). Hence, leather described as 7 to 8 oz is 7/64 to 8/64 inches (2.8 to 3.2 mm) thick. The weight is usually given as a range because the inherent variability of the material makes ensuring a precise thickness very difficult. Other leather manufacturers state the thickness directly in millimeters.

7. Cоотнесите тип кожи из колонки А с его описанием в колонке В.

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4.Sunlight will cause the natural vachetta leather to darken in shade.

5.Bonded leather is famous for its proven durability.

6.Top-grain thicknesses are described using weight units of millimeters.

10.Дайте краткую аннотацию текста к упражнению 5.

Lesson 14. Forms of Tanned Leather

1. Прочитайте и переведите следующие глаголы:

to convert, to tan, to discolour, to soak, to dry, to shrink, to gelatinize, to harden, to immerse, to invent, to lose shape, to refer, to phase out, to oxidize, to require, to realize, to mix, to rot, to scrap, to soak, to stretch, to lump, to lace, to stitch, to taw, to oil, to improve, to supplement, to wash out

2. Прочитайте следующие интернациональные слова вслух и, основываясь на значениях соответствующих русских

слов, определите их значение:

ingredients, gelatinize, chromium sulfate, esoteric, glutaraldehyde, oxazolidine, aldehyde, aromatic, polymer, taxidermy, novolac, neradol, synthetic, melamine, resin, aluminium, gelatin

3.Прочитайте и переведите следующие прилагательные: putrescible, durable, long-lasting, versatile, various, supple, strong, stable, hard, rigid, brittle, pliable, pale cream, chrome-free, water absorbent, exceptional, free, stiff, similar

4.Прочитайте и переведите названия форм кожи:

Cattlehide

Putrescible skin

Vegetable-tanned leather

Boiled leather

Chrome-tanned leather

Aldehyde-tanned leather

Wet-white leather

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Chrome-free leather

Brain-tanned leather

Chamois leather

Synthetic-tanned leather

Alum-tanned leather

6. Прочитайте и переведите текст.

Forms of Tanned Leather

Leather is a material created through the tanning of hides and skins of animals, primarily cattlehide. The tanning process converts the putrescible skin into a durable, long-lasting and versatile natural material for various uses.

Leather formed the basis of ancient technology together with wood. The leather industry and the fur industry are distinct industries

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that are differentiated by the importance of their raw materials. In the leather industry the raw materials are by-products of the meat industry, with the meat having higher value than the skin. The fur industry uses raw materials that are higher in value than the meat and hence the meat is classified as a by-product. Taxidermy also makes use of the skin of animals, but generally the head and part of the back are used. Hides and skins are also used in the manufacture of glue and gelatin.

There are a number of processes whereby the skin of an animal can be formed into a supple, strong material commonly called leather.

Vegetable-tanned leather is tanned using tannin (hence the name "tanning") and other ingredients found in vegetable matter, tree bark, and other such sources. It is supple and brown in colour, with the exact shade depending on the mix of chemicals and the colour of the skin. Vegetable-tanned leather is not stable in water; it tends to discolour, and if left to soak and then dry it will shrink and become less supple and harder. In hot water, it will shrink drastically and partly gelatinize, becoming rigid and eventually brittle. Boiled leather is an example of this where the leather has been hardened by being immersed in hot water, or in boiled wax or similar substances. Historically, it was occasionally used as armour after hardening, and it has also been used for book binding. This is the only form of leather suitable for use in leather carving or stamping.

Chrome-tanned leather, invented in 1858, is tanned using chromium sulfate and other salts of chromium. It is more supple and pliable than vegetable-tanned leather, and does not discolour or lose shape as drastically in water as vegetable-tanned. It is also known as wet-blue for its colour derived from the chromium. More esoteric colours are possible using chrome tanning.

Aldehyde-tanned leather is tanned using glutaraldehyde or oxazolidine compounds. This is the leather that most tanners refer to as wet-white leather due to its pale cream or white colour. It is the main type of leather used in chrome-free leather often seen in infant's shoes and in automobiles made with chrome-free leather. Formaldehyde tanning (being phased out due to its danger to workers

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and the sensitivity of many people to formaldehyde) is another method of aldehyde tanning. Brain-tanned leathers fall into this category and are exceptionally water absorbent. Brain tanned leathers are made by a labor-intensive process which uses emulsified oils, often those of animal brains. They are known for their exceptional softness and their ability to be washed. chamois leather also falls into the category of aldehyde tanning and like brain tanning produces a highly water absorbent leather. Chamois leather is made by using oils (traditionally cod oil) that oxidize easily to produce the aldehydes that tan the leather.

Synthetic-tanned leather is tanned using aromatic polymers such as the novolac or neradol types. This leather is white in colour and was invented when vegetable tannins were in short supply, i.e. during the Second World War. Melamine and other amino-functional resins fall into this category as well and they provide the filling that modern leathers often require. Urea-formaldehyde resins were also used in this tanning method until dissatisfaction about the formation of free formaldehyde was realised.

Alum-tanned leather is tanned using aluminium salts mixed with a variety of binders and protein sources, such as flour, egg yolk, etc. Purists argue that alum-tanned leather is technically "tawed" and not tanned, as the resulting material will rot in water. Very light shades of leather are possible using this process, but the resulting material is not as supple as vegetable-tanned leather.

Rawhide is made by scraping the skin thin, soaking it in lime, and then stretching it while it dries. Like alum-tanning, rawhide is not technically "leather", but is usually lumped in with the other forms. Rawhide is stiffer and more brittle than other forms of leather, and is primarily found in uses such as drum heads where it does not need to flex significantly; it is also cut up into cords for use in lacing or stitching, or for making many varieties of dog chews.

Leather, usually vegetable-tanned leather, can be oiled to improve its water resistance. This supplements the natural oils remaining in the leather itself, which can be washed out through repeated exposure to water. Frequent oiling of leather, with mink oil, neatsfoot oil or a similar material, keeps it supple and improves its

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lifespan dramatically. Leather with the hair still attached is called hair-on.

7.Ответьте на вопросы.

1.What form of leather is suitable for leather carving or stamping?

2.What is the difference between vegetable-tanned and chrome tanned leather?

3.What methods are used in aldehyde tanning?

4.Which kind of oil is used to keep leather supple and improves its lifespan dramatically?

8.Определите, являются ли следующие утверждения

верными в соответствии с текстом упражнения 6.

1.Alum-tanned leather is not stable in water; it tends to discolour, and if left to soak and then dry it will shrink and become less supple and harder.

2.Historically, vegetable-tanned leather was occasionally used as drum heads after hardening.

3.Chrome-tanned leather is the leather that most tanners refer to as wet-white leather due to its pale cream or white colour.

4.Brain tanned leathers are known for their exceptional softness and their ability to be washed.

5.Chamois leather is made by using ingredients found in vegetable matter.

6.Urea-formaldehyde resins are still used in the production of synthetic-tanned leather.

9.Заполните таблицу информацией из текста упражнения 6.

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Leather

Aldehyde-

tanned

Leather

Synthetic-

tanned

Leather

Alumtanned Leather

Rawhide

10. Дайте краткую аннотацию текста к упражнению 6.

Unit IV

FUR

Lesson 15. His Royal Majesty, Sable

1. Прочитайте следующие интернациональные слова вслух и, основываясь на значениях соответствующих русских

слов, определите их значение:

tsar, status, visiting card, elite, monarchy, designer, charm

2. Прочитайте и переведите следующие глаголы:

to enhance, to impress, to remain, to accentuate, to wear, to acquire, to pay attention to, to divide, to vary, to look like, to be proud of, to breed, to argue, to blench, to possess, to maintain, to differ

3.Прочитайте и переведите следующие прилагательные: royal, inseparable, obvious, glamorous, successful, expensive, incomparable, wild, valuable, noble, magnificent

4.Подберите эквивалентный перевод словосочетаний из колонки А в колонке В.

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5. Прочитайте и переведите текст.

His Royal Majesty, Sable

For many centuries Russian furs softly but glamorously enhanced greatness of the Russian Tsars and impressed foreigners. Notions “royal” and “sable” were inseparable.

Currently sable still remains a luxury item and accentuates the status of its owner. To wear sable is the same as to drive a RollsRoyce, that’s why it is obvious that the owners of this glamorous fur are successful and rich people.

If you decide to acquire a sable item, you should be careful choosing it because it will immediately become your visiting card. First of all pay attention to the origin of the fur. Sable is closely related to marten. Sometimes the labels of expensive and beautiful fur clothes say that the items were made of Canadian sable. It is, in fact, American marten. Its fur is beautiful too but its quality is incomparable to sable fur.

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