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Leather
Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, and aquatic animals such as seals and alligators. Leather can be used to make a variety of items, including clothing, footwear, handbags, furniture, tools and sports equipment, and lasts for decades. Leather making has been practiced for more than 7,000 years and the leading producers of leather today are China and India. Animal rights groups claim that modern commercial leather making and the consumption of its products is unethically killing animals. According to the life-cycle assessment (LCA) report for the United Nations Industrial Development Organization, 99% of the raw hides and skins used in the production of leather derive from animals raised for meat and/or dairy production. Critics of tanneries claim that they engage in uns ...
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Leather Tanning, Fes
Leather is a strong, flexible and durable material obtained from the tanning (leather), tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, and aquatic animals such as seals and alligators. Leather can be used to make a variety of items, including clothing, footwear, handbags, furniture, tools and sports equipment, and lasts for decades. Leather making has been practiced for more than 7,000 years and the leading producers of leather today are China and India. Animal rights groups claim that modern commercial leather making and the consumption of its products is unethically killing animals. According to the Life-cycle assessment, life-cycle assessment (LCA) report for the United Nations Industrial Development Organization, 99% of the raw hides and skins used in the production of leather derive from animals raised for meat and/or dairy production. Critics o ...
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Whitening (leather Processing)
The leather manufacturing process is divided into three sub-processes: preparatory stages, tanning and crusting. All true leathers will undergo these sub-processes. A further sub-process, surface coating may be added into the sequence. The list of operations that leathers undergo vary with the type of leather. Production management The leather making process is in general restricted to batch processing, but if the surface coating sub-process is added then some continuous processing can be included. The operation flow has to follow the preparatory → tanning → crusting → surface coating sub-process order without deviation, but some of the sub-processes can be omitted to make certain leathers (or partially tanned/ untanned products). Preparatory stages The preparatory stages are when the hide/skin is prepared for tanning. During the preparatory stages many of the unwanted raw skin components are removed. Many options for pretreatment of the skin exist. Not all of the options ma ...
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Tanning (leather)
Tanning is the process of treating Skinning, skins and Hide (skin), hides of animals to produce leather. A tannery is the place where the skins are processed. Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition and coloring. Before tanning, the skins are dehaired, degreased, desalted and soaked in water over a period of six hours to two days. Historically this process was considered a noxious or "odoriferous trade" and relegated to the outskirts of town. Historically, tanning used tannin, an acidic chemical compound from which the tanning process draws its name, derived from the bark of certain trees. An alternative method, developed in the 1800s, is chrome tanning, where chromium salts are used instead of natural tannins. History The English word for tanning is from medieval Latin , derivative of (oak bark), from French (tanbark), from old-Cornish (red oak). ...
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Tanning (leather)
Tanning is the process of treating Skinning, skins and Hide (skin), hides of animals to produce leather. A tannery is the place where the skins are processed. Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition and coloring. Before tanning, the skins are dehaired, degreased, desalted and soaked in water over a period of six hours to two days. Historically this process was considered a noxious or "odoriferous trade" and relegated to the outskirts of town. Historically, tanning used tannin, an acidic chemical compound from which the tanning process draws its name, derived from the bark of certain trees. An alternative method, developed in the 1800s, is chrome tanning, where chromium salts are used instead of natural tannins. History The English word for tanning is from medieval Latin , derivative of (oak bark), from French (tanbark), from old-Cornish (red oak). ...
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Boiled Leather
Boiled leather, often referred to by its French translation, cuir bouilli (), was a historical material common in the Middle Ages and Early Modern Period and used for various purposes. It was leather that had been treated so that it became tough and rigid, as well as able to hold moulded decoration. It was the usual material for the robust carrying-cases that were made for important pieces of metalwork, instruments such as astrolabes, personal sets of cutlery, books, pens and the like. It was used for some armour, being both much cheaper and much lighter than plate armour, but could not withstand a direct blow from a blade, nor a gunshot. Alternative names are "moulded leather" and "hardened leather". In the course of making the material it becomes very soft, and can be impressed into a mould to give it the desired shape and decoration, which most surviving examples have. Pieces such as chests and coffers also usually have a wooden inner core. Various recipes for making cuir bou ...
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Neatsfoot Oil
Neatsfoot oil is a yellow oil rendered and purified from the shin bones and feet (but not the hooves) of cattle. "Neat" in the oil's name comes from an Old English word for cattle. Neatsfoot oil is used as a conditioning, softening and preservative agent for leather. In the 18th century, it was also used medicinally as a topical application for dry scaly skin conditions. In spite of its name, "prime neatsfoot oil" (or "neatsfoot oil compound") is a blend of actual neatsfoot oil and non-animal oils, generally mineral or other petroleum-based oils. Characteristics Fat from warm-blooded animals normally has a high melting point, becoming hard when cool, but neatsfoot oil remains liquid at room temperature. This is because the relatively slender legs and feet of animals such as cattle are adapted to tolerate and maintain much lower temperatures than that of the body core, using countercurrent heat exchange in the legs between warm arterial and cooler venous blood. Other body fa ...
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Liming (leather Processing)
Liming is a process used for parchment or leather processing, in which hides are soaked in an alkali solution. It is performed using a drum and paddle or a pit. Its objectives are: * Removal of interfibrillary proteins. * Removal of Keratin proteins. * Collagen swelling due to the alkaline pH. * Collagen fibre bundle splitting. * Removal of natural grease and fatsS.S. Dutta, ''An Introduction to the Principles of Leather Manufacture'', p. 160 Liming operations of cattle hides usually last 18 hours and are generally associated with the alkaline phase of beamhouse operations. Removal of interfibrillary proteins The interfibrillary proteins are denatured by the presence of alkali (particularly sodium sulfide), rendered soluble, facilitating their removal from the leather. Removal is done by the mechanical action of liming or reliming, but more prominently when the pelt is deswelled (during deliming). Failure to remove these proteins results in a hard, tinny leather (due to fib ...
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Collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content. Collagen consists of amino acids bound together to form a triple helix of elongated fibril known as a collagen helix. It is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin. Depending upon the degree of mineralization, collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes one to two percent of muscle tissue and accounts for 6% of the weight of the skeletal muscle tissue. The fibroblast is the most common cell that crea ...
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Deliming
The deliming operation in leather processing is a drum/paddle or pit based operation where two main objectives are met: * Removal of alkali from the pelt and the consequent deswelling of the fibres. * Lowering of the liquor pH to the values used in the bating process. Deliming operations of cattle hides usually last two hours and are generally associated with the alkaline phase of beamhouse operations. The progress of deliming in pelts is monitored by the checking of pH values of process liquors and in the cutting of a pelt cross-section. Phenolphthalein is used to monitor deliming pelt cross-sectional progress. Removal of pelt alkali and deswelling * As an acid is added it lowers the pH value of the internal pelt solution. This neutralizes the solution alkalinity. The lowering of the pH results in rapid protonation of the collagen basic groups. Lowering of liquor pH * The acid present in the deliming agents neutralizes the process liquor pH. Typical values after effective, thor ...
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Tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', from Medieval Latin ''tannāre'', from ''tannum'', oak bark) refers to the use of oak and other bark in tanning animal hides into leather. By extension, the term ''tannin'' is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with various macromolecules. The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation (acting as pesticides) and might help in regulating plant growth. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit, red wine or tea. Likewise, the destruction or modification of t ...
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Bark Mill
Bark mills, also known as Catskill's mills, are water, steam, horse, ox or wind-powered edge mills used to process the bark, roots, and branches of various tree species into a fine powder known as tanbark, used for tanning leather. This powdering allowed the tannin to be extracted more efficiently from its woody source material.Muspratt Bark Mill
Retrieved : 2011-02-03
A barker would strip the bark from trees so that it might be ground in such mills, and the dried bark was often stored in bark houses.


Bark mill machinery

Various machinery was used to chop, grind, riddle and pound the bark. These included Farcot’s bark-cutting machi ...
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Cattle
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult males are referred to as bulls. Cattle are commonly raised as livestock for meat (beef or veal, see beef cattle), for milk (see dairy cattle), and for hides, which are used to make leather. They are used as riding animals and draft animals ( oxen or bullocks, which pull carts, plows and other implements). Another product of cattle is their dung, which can be used to create manure or fuel. In some regions, such as parts of India, cattle have significant religious significance. Cattle, mostly small breeds such as the Miniature Zebu, are also kept as pets. Different types of cattle are common to different geographic areas. Taurine cattle are found primarily in Europe and temperate areas of Asia, the Americas, and Australia. Zebus (also ...
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