Information AboutLeather |
| CATEGORIES ABOUT LEATHER | |
| leatherleather | |
| hides | |
|
Leather is a material created through the Tanning of Hide s and Skin s of Animal s, primarily Cattle hide. The tanning process converts the Putrescible skin into a durable, long-lasting and versatile natural material for various uses. Leather is an important material with many uses. Together with Wood , leather formed the basis of much ancient Technology . The leather industry and the Fur industry are distinct industries 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 . FORMS OF LEATHER There are a number of processes whereby the skin of an animal can be formed into a supple, strong material commonly called leather.
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 lifespan dramatically. Leather with the hair still attached is called ''hair-on''. Leather types In general, leather is sold in three forms:
Other less-common leathers include:
There are two other descriptions of leather commonly used in specialty products, such as briefcases, wallets, and luggage.
The following are not 'true' leathers, but contain leather material.
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 measurement is square metre, square decimetre or square foot. The thickness is also important, and this is measured using a thickness gauge (the unit of measurement is millimetres, 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:
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 millimetres. Leather from other animals ]] Today, most leather is made of Cattle skin, but many exceptions exist. Lamb and deer skin are used for soft leather in more expensive apparels. Kangaroo skin is used to make items which need to be strong but flexible, it is the only material used in high quality Bullwhip s. Kangaroo leather is favored by some Motorcyclists for use in Motorcycle Leathers specifically because of its lighter weight and higher abrasion resistance compared to cowhide, thus providing greater protecting in case of a fall on the roadway. Kangaroo leather is also used for high performance soccer footwear. Leather made from more exotic skins has at different times in history been considered very beautiful. For this reason certain Snake s and Crocodile s have been hunted to near extinction. In the 1970s , Ostrich farming for their feathers became popular, and ostrich leather became available as a side product. There are different processes to produce different finishes for many applications, i.e., upholstery, footwear, automotive products, accessories and clothing. Ostrich leather is considered one of the finest and most durable in the world and is currently used by many major fashion houses such as Hermès , Prada , Gucci , and Louis Vuitton . Ostrich leather has a characteristic "goose bump" look because of the large follicles from which the feathers grew. In Thailand , Sting Ray leather is used in wallets and belts in the same way as regular bovine leather. Sting ray leather is as tough and durable as hard plastic. The leather is often dyed black and covered with tiny round bumps in the natural pattern of the back ridge of an animal. These bumps are then usually dyed white to highlight the decoration. Leather clothing is also popular in Thailand. In the United States, Bison leather has become popular. It is used for gloves, jackets and some baseball gloves. It is rugged but supple and has a waxy feel. Overall, leather comes from a variety of other sources, including the skins of cattle, hogs, goats, sheep, alligators, ostriches, kangaroos. The Facts About Leather from CowsAreCool.com LEATHER PRODUCTION PROCESSES The leather manufacturing process is divided into 3 fundamental sub-processes: preparatory stages, '''tanning''' and '''crusting'''. All true leathers will undergo these sub-processes. A further sub-process, surface coating can be added into the leather process sequence but not all leathers receive surface treatment. It's difficult to have a list of operations that all leathers must undergo, as there are so many types of leather. The preparatory stages are when the hide/skin is prepared for tanning. Preparatory stages may include: Preservation , Soaking , Liming , Unhairing , Fleshing , Splitting , Reliming , Deliming , Bating , Degreasing , Frizing , Bleaching , Pickling and Depickling . Tanning is when the skin fibres are stabilised for resistance to bacterial attack so the hides remain flexible on drying and show an increase in thermal stability. Tanning processes include penetration and fixation. Crusting is when the hide/skin is thinned, retanned and lubricated. Often a coloring operation is included in the crusting sub-process. The chemicals added during crusting have to be fixed in place. The culmination of the crusting sub-process is the drying and softening operations. Crusting may include the following operations: Wetting Back , Sammying , Splitting , Shaving , Rechroming Neutralisation , Retanning , Dyeing , Fatliquoring , Filling , Stuffing , Stripping , Whitening , Fixation , Setting , Drying , Conditioning , Milling , Staking and Buffing . For some leathers a surface coating is applied. Tanners refer to this as finishing. Finishing operations may include: Oiling , Brushing , Padding , Impregnation , Buffing , Spraying , Roller Coating , Curtain Coating , Polishing , Plating , Embossing , Ironing , Ironing/combing (for hair-on)and Glazing . ROLE OF ENZYMES IN LEATHER PRODUCTION Enzymes like proteases, lipases and amylases have important role in soaking, dehairing, degreasing and bating operations of leather manufacturing. Proteases are the most commonly used enzymes in leather production. The criteria for selection of best protease is that it should be non- collagenolytic and non- keratinolytic in nature. It has property to hydrolyze casein,elastin,albumin and globuline like proteins. Lipases are used in degreasing operation to hydrolyze fat materials of skin/ hide. Amylases are also used in bating of animal skins/ hide. Protease based enzymes, when used in soaking hydrolyze all the non structured proteins which are not essential for leather making. Elastin, which is a non structured protein is the binding material between the upper grain layer and the lower collagenetic substrate which is the actual leather. Complete removal of the elastin will result in double layer of grain and if not removed properly, the elastin when subjected to liming will get immuned and hardened resulting in a loose grain. PRESERVATION AND CONDITIONING OF LEATHER The natural fibers of leather will break down with the passage of time. Acidic leathers are particularly vulnerable to Red Rot , which causes powdering of the surface and a change in consistency. Damage from red rot is aggravated by high temperatures and relative humidities, and is irreversible. Exposure to long periods of low relative humidities (below 40%) can cause leather to become desiccated, irreversibly changing the fibrous structure of the leather. Various treatments are available such as Conditioner s, but these are not recommended by Conservators since they impregnate the structure of the leather artifact with active chemicals, are sticky, and attract stains. WORKING WITH LEATHER See Also: Leather crafting Leather can be decorated by a variety of methods, including Pyrography and Beading . CORDWAIN Cordwain, once a synonym to . LEATHER IN MODERN CULTURE Leather, due to its excellent abrasion and wind resistance, found a use in rugged occupations. The enduring image of a Cowboy in leather chaps gave way to the leather-jacketed and leather-helmeted aviator. When motorcycles were invented, some riders took to wearing heavy leather jackets to protect from road rash and wind blast; some also wear chaps or full leather pants to protect the lower body. Many sports still use leather to help in playing the game or protecting players: due to its flexible nature it can be formed and flexed for the occasion. As leather can also be a Metonym ical term for objects made from it, the term leathering is as logical as ''tanning'' in the sense of a Physical Punishment (such as a severe Spanking ) applied with a leather Whip , Martinet etcetera. Due to leather's physical attributes, the fact that it is almost impossible to rip or break, Professional Wrestling federations use leather in all of their championship belts. This is also the case with all other championship belts in boxing, martial arts etc. Leather Fetishism is the name popularly used to describe a Fetishistic attraction to people wearing leather, or in certain cases, to the garments themselves. The word leather itself came to be used as synonymous with Sado-masochism in the 1980s, after achieving that status in homosexual jargon in the 1970s. A number of Rock Group s, particularly Heavy Metal groups such as Scorpions and Judas Priest , are well-known for wearing leather clothing. Leather clothing, particularly jackets, almost come as standard in the heavy metal subculture. Extreme Metal bands, especially Black Metal bands, have extensive leather clothing, i.e. leather trousers, accessories etc. In today's times, many cars and trucks come optional or standard with 'leather' seating. This can range from cheap vinyl material, found on some low cost vehicles, to Nappa leather, found on luxury car brands like Mercedes-Benz . Leather Biodegrade s slowly, e.g. a pair of Leather Shoes takes 25-40 years to decompose. ESPN anchor and personality Chris Berman is reportedly "With Leather." RELIGIOUS SENSITIVITIES TO LEATHER In countries with harmonious multi-religious environments, leather vendors choose to announce the leather used in their products. For example, leather shoes bear a label identifying the animal from which the leather was taken. Thus, a follower of Islam would not accidentally purchase Porcine leather, and a Hindu could avoid Bovine leather. Such awareness also increased the demand for religiously 'neutral' leather like ostrich and deer leather. CONCERN FOR ANIMALS AND ALTERNATIVES Some Vegan and Animal Rights Activists have boycotted use of all leather items, believing the practice of wearing skins is unnecessary and vulgar in today's society. Animal rights groups such as PETA have issued fact sheets calling for boycotts and encouraging use of alternative materials such as Synthetic Leathers . Many pseudo-leather materials have been developed, allowing those who wish to wear leather-like garments to do so without actually wearing leather. One example of this is Vegan Microfiber , which claims to be stronger than leather when manufactured with strength in mind. Vinyl materials, Pleather , Durabuck , NuSuede , Hydrolite , and other alternatives exist, providing some features similar to leather. SEE ALSO
EXTERNAL LINKS REFERENCES |
|
|