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Created with Fabric.js 1.4.5 Animal Soaking Dehairing Bating Degreasing Leather Soaking is first important operation of leather processing. Hides and skins received into a tannery are in the four conditions, as green or fresh, as wet salted, as dry salted or as dried. It is advisable to carry out soaking for all types of skin and hides to obtain best quality leather.Soaking cleans hides and skins by removing dirt, blood, flesh, grease, dung etc. and most importantly, re-hydrates them to bring skins as far as possible back to state of green hides. Soaking agents fall into three categories, like Chemical Agents, Surface-active agents and Enzymatic agents.Enzymatic agents are biocatalyst. Specific protease and lipase enzymes enhance water uptake by dissolving intrafibrillary proteins that cement fibres together and disperse fats and oils together with dirt and other contaminants present on skin. The conventional and most wide spread way to remove hair from bovine hides is to use lime and sodium sulphide in a hair-burning process. They dissolve the hair and open up the fibre structure.Most importantly, enzyme-assisted un-hairing results in a cleaner grain surface and improved areayield and softness. The use of a specific protease also offers tanneries a number of options. For instance, the sulphide and lime requirements can be reduced by as much as 40% while maintaining the same liming time. Alternatively tanners can shorten the liming time by at least half without any loss of quality. Another possibility is to avoid the use of amines, which can be converted into carcinogenic compounds. To make leather pliable, the hides and skins require an enzymatic treatment before tanning know as bating. During bating, scud is loosened and other unwanted proteins are removed. Bating de-swells swollen pelts and prepares leather for tanning. It makes the grain surface of the finished leather clean, smooth and fine. Bating with enzymes is an indispensable operation of leather processing to obtain best quality of leather and cannot be substituted with a chemical process.Traditional methods for bating employed manureof dog, pigeon or hen. These were very unpleasant, unreliable and slow methods. Bio-technical developments in science have now completely replaced these methods with use of industrial enzymes. Processes Involving Enzymes Alkaline Lipase and Alkaline Protease UseIn TheProductionOf Leather Benefits Concerns vs. -Cheaper replacement forchemicals-Higher quality-Non-pollutant-hair retrieval for otherpurposes-lower odor level-reduced Biochemical OxygenDemand (BOD) and ChemicalOxygen Demand (COD) -Lipases do not removeall types of fats as solvents do-Not as effective as chemicals and solvents during certain partsof the leather-making process Lipases are a type of enzyme that specifically degradesfat and so cannot damage the leather itself. Lipases hydrolyse not just the fat on the outside of the hides and skins, but also the fat inside the skin structure. Once most of the natural fat has been removed, subsequent chemical treatments such as tanning, re-tanning and dyeing have a better effect.The main advantages of using lipases are a more uniformcolour and a cleaner appearance. Lipases also improve the production of hydrophobic (waterproof) leather; makers of leather for car upholstery have commented that 'fogging' is reduced. This is the term for the build-up of a film of chemicals on the inside of car windscreensLipases represent a more environmentally sound method of removing fat. For bovine hides, lipases allow tensides to be replaced completely. For sheepskins, which contain up to 40% fat, the use of solvents is very common and these can also be replaced with lipases and surfactants. Solvents tend to dry out the skin and give it a pale colourIf surfactants are used for sheepskins, they are usually not as effective and may be harmful to the environment. Stronger surfactants such as nonyl phenol ethoxylate have a better effect but they are more detrimental to the environment. When using lipases, the original surfactant dosage can be reduced by at least 50% in the case of both sheepskins and pigskins. In addition, nonyl phenolethoxylate can be substituted with more biodegradable surfactants. Dima Romashin