In ancient history , tanning was considered toxic or “odiferous trade” and relegated to the outskirts of town , including the poor . In fact , tanning methods , the old smelly tannery still isolated from those towns today where the old methods are used. The ancients used leather waterskins, bags , harnesses, boats, armor, trembling, scabbard , boots and sandals. Around 2500 BC , the Sumerians began using leather , copper bolts, carriage wheels.
Dry skin, tanning stiff , usually arrive dirty and bloody mud. First , the ancient leather tanning soak them in water for cleaning and softening . Then they would pound and scour the skin to remove any remaining meat and fat. Next, remove the skin from the hair fiber cobbler needs . It is then impregnated by immersion in either a salt solution in the urine rot skin on the skin , with a soda-lime mixture is applied to it , or to simply check . After the hair fiber leather relax knife scrape it off.
Once the hair has been removed , softened leather material ( see below ) into a solution by the impact of brain skin or soaked in animal feces in the skin. This is a common dog feces or pigeons. Sometimes dung mixed with water in a large vat, and prepare the skin pinch in stool water until they become soft, but not too soft. Ancient tanner might use his skin rubbed feces in water, mixing may last two to three hours .
This is the urine, feces and rotting animal flesh , so that the ancient tanneries so odiferous this combination.
As a child collecting stool common sight in the old town . Located in the corner is also common , human urine can be collected using a tanning or washerwoman ‘s ” piss pot .” In some variant of this method, cedar oil, alum or tannic acid is applied to the skin as a tanning agent . As the skin is stretched , it loses moisture and absorption.
The skin becomes leftover glue. Leather tannery wastewater will be placed in a vat of water and let them deteriorate for months. The mixture will be placed over the fire to boil water to produce hide glue .
Changing these methods are still used to do -it-yourself outdoor sports enthusiasts tan leather. The use of brains and ideas , each animal ( not including buffalo ) have sufficient cause brain tanning process , said : ” Every animal has enough brains to preserve its own hide , dead or alive .”
Modern methods of tanning
The first stage is the preparation of tanning . The second stage is the actual tanning and other chemical treatment. Retanning material and a dye used in the third stage to provide physical strength , and according to the desired properties of the final product . This is called tanning. After the fourth stage of any chemical surface treatment material is applied to the coated surface of the non- completion , if desired . This final stage is called finishing.
Ready to start using salted raw hides them. Curing is employed to check , since there may be a bacterial infection , due to the time lag of the opportunity to deal with the protein substance from its putrifaction purchase (collagen ) . It eliminates having excess skin from the inside of the water flow , because of the difference in osmotic pressure . Therefore , the moisture content of raw hides and skins have been great reduced.In lot of salty pickled hides and skins , and then pressed into a pack of about 30 days . Leather and curing brine bath and stirred for about 16 hours . Typically, the method is substantially the chance of bacterial growth disadvantage for curing . Therefore , curing is maintained at a very low temperature to make the appearance of
Skin, and then soaked in clean water to remove salts , and the water back to the primary content desired level , so that the skin can be used raw materials for the chemical treatment in an aqueous medium. This process is called ” soaking” , sometimes with water , moisturizing agents in the skin has become very dry low percentage of use .
Dawn process leather and fur
After soaking, the treated skin was soaked in the next processing operation wherein the curing agent is not sharpened like lime , cyanide , amines, etc.The main purpose of this operation is
1 ) Remove the hair, nails and horny matter 2) remove interfibrillary soluble proteins, such as mucin part 3 ) expansion , Fiber Division desired level 4 ) Remove the natural oils to some extent 5 ) tanned collagen appropriate conditions satisfaction
Reduced hair is dependent on the amino acid called cystine, which is kind of hair keratin , and the breaking of covalent disulfide cystine attached, to break the hydrogen reducing agent is supplied by sharpening cystine molecules wools.The characteristics.
The isoelectric point of the collagen is also transferred to about 4.7 , tends to be more acidic , the lime tanning .
Dawn process is using depilatory
1 ) sodium sulfide 2 ) NaOH 3 ) dithionite 4 ) arsenic sulfide 5 ) calcium hydride 6 ) dimethyl amine 7 ) Sodium Sulphydrate
Most of the hair with the machine , then removed with the same hand that is blunt remaining hair , the process is called scudding deleted . Depending on the final use of the leather , skins can be used to soften the treatment process are known as ” softening” of the enzyme. However , before softening , pH, decrease in collagen to a lower level so that it can be enzymes. This process is called ” de-ashing .” After completion , a rawhide is so softened , mineral tanning process under acid and salt to make done.This collagen to reduce to a very low pH levels , in order to penetrate into the mineral tanning agent, the mixture of materials . This process is known as “acid .” Check the adverse effects of a sudden drop of the salt barrier material twice as fast as the acid and pH .
Tanned with vegetable or mineral can be a way . Prior to tanning , skin unhaired, degreased , desalted and soaked in water for a period of 6-2 hours. When , during immersion in order to prevent bacterial growth on the skin damage , biocides , such as pentachlorophenol, are used.
Using tannin ( this is the name comes from tanning ) vegetable tanned . Naturally present in the bark tannin . The main bark is used in modern chestnut , oak , tanoak, hemlock, quebracho , mangrove , wattle and myrobalan . Soaking the leather is stretched frame cycle , increasing the concentration of tannin vat . Vegetable tanned leather is flexible luggage and furniture.
Mineral often used in the form of basic chromium sulfate chrome tanning . After picking, it is being used. Once the chrome penetration in the material to achieve the desired level , pH value of the material is raised again to facilitate this process. This is called alkaline. In the original state chrome tanned leather is blue, it is called ” wet blue .” Chrome than vegetable tanned ( this part of the process less than a day ) , used in the production of stretchable , ideal for purses and clothing more fast.
Depending on the desired finished, waxing can be hidden , rolled, lubricated , injected into the oil , split, shaved his head, of course , dyed. Suede , nubucks etc. are raised from the surface roughness of the ends of the rolled leather fluff .