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জেনে নিন ৩৭তম লিখিত English পরীক্ষায় কম্প্রেহিনসন যে ওয়য়েবসাইট থেকে এসেছে

 ওয়য়েবসাইট ১ ক্লিক করুন

 ওয়য়েবসাইট ২ ক্লিক করুন

 

Hides and skins are the raw material of the leather manufacturer or tanner. When man first used animal skins is not known. Skins, even when preserved by tanning, do not last as long as stone, pottery, metals and bone, and our knowledge about the early use of skins is vague. However, the numerous flint scrapers and bone or ivory sewing needles in our museums show that tens of thousands of years ago, in the early Stone Age, skins were prepared and used long before textiles. Nowadays, hides and skins are essential raw materials and important articles of commerce.
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Any animal skin can be made into leather, but the skins chiefly used come from cattle, sheep, goats, pigs and horses. To a lesser extent the skins from dogs, deer, reptiles, marine animals, fish and birds are also used. Snakes, lizards, seals, whales, and sharks all contribute to leather manu­facture.
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‘Hide’ is the trade word for the skins of the larger animals such as full grown cattle and horses; and’ skin’ for the smaller animals, and immature large animals such as ponies and calves. Some skins are made into leather after the hair or wool has been removed; but the skins of the fur-bearing animals and sometimes of sheep, lambs and ponies are processed, or ‘dressed’, with the hair or wool still in place.
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Most cattle hides come from South America, the U.S.A. and from Australia with smaller quantities from East and West Africa, Central America and the Sudan. Sheepskins come from Australia and New Zealand, and the best goat skins come from India, Pakistan, Ethiopia, Arabia and Nigeria.
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There is usually a long interval between the flaying, or stripping, of the skin from the animal and putting it into the tannery for processing. If the flayed skins were left wet, they would go bad, just like meat; they must therefore be preserved in some way. The commonest method is salting. This involves sprinkling the skins with salt on their inner side; or immersing the skins completely in strong salt solution for some hours, after which they are drained and sprinkled with solid salt.
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Another method of drying is to stretch the skins out on the ground, or on frames and to dry them in the sun, or even better in the shade. Beetles and other insects eat skins and must be kept away by the use of some chemical such as D.D.T. The dried skins are called ‘crust’ leather and are sent in this form to the tanneries for the very complicated process of tanning. After tanning, only the ‘corium’ or middle layer of the skin is left to provide leather as we know it. It is to the closely knit fiber structure of the corium that leather owes its virtues of flexibility, strength and elasticity, its resistance to rubbing and its unique power of allowing water vapor and air to pass through it while resisting penetration by liquid water itself.

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