< p > (1) scribing knife and knife hole peeling or preliminary processing, use the knife to cut the surface of the board with an impermeable crack called a tracing knife, and cut the skin into a knife hole. The depth of scratching is more than 1/3 above skin thickness, and the skin tension is seriously affected. < /p >
< p > (two) leakage due to improper skin stripping, such as picking up the rear gear, directly from the abdominal line to the leg skin directly, so that part of the abdominal skin and buttocks skin together, and the anus moved to the surface of the skin plate. It not only affects the appearance of leather, but also affects the yield of fur. < /p >
< p > (three) when the skin is stripped, the position of the abdominal skin is not correct, making the area of the two sides of the ridge of the skin plate different. This not only affects the shape of the skin, but also affects the yield of fur or leather. < /p >
< p > (four) on the top of the skin, the tail is not turned off the inside of the anus, but the outer skin is cut off from the buttocks, and the tail is drawn from the small mouth. Because the small mouth is in the main part, it reduces the fur value of the skin sheet. < /p >
< p > (five) when scraping the hair, it will hurt the hair follicle when it is scraping the oil or scraping it against the direction of the hair root. The hair root will appear on the board. When the light weight is made, the firmness of the wool on the skin plate is reduced, and the heavy person has no value in making fur. < /p >
< p > (six) breaking, breaking, breaking and sewing with thread. The break can be divided into two parts, namely, through break, oblique break and transverse breach. < /p >
< p > (seven) the small cylindrical skin of the last skin should be oversized with wooden sticks to reduce the density of the pile. < /p >
< p > (eight) the skin of the arrow pole is pulled into a long tubular shape, which affects the yield of the skin. < /p >
< p > (nine) in the winter, the skin of the frozen tanning board is pale, porous, thick and lustrous, and its physical properties are reduced. < /p >
< p > (ten) wrinkled skin fresh skin is not flattened in the air, and the skin plate is not easy to dry at the crinkle. It can cause the disadvantages such as stuffy hair removal and so on, and reduce the value of making fur. < /p >
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< p > (eleven) when the hair is not peeled or peeled in time, it is not dried in time, fresh skin is not properly preserved or dry skin is in contact with water, and the room temperature is relatively high. Under the action of mold and badge organisms, the protein in the skin plate is decomposed, resulting in the loss of the wool fiber. The damaged skin plates are dark grey or gray green. Because of the expansion of the area in tanning, the value of fur making is seriously affected. < /p >
< p > (twelve) when the dry skin is dried out of the cylinder, the skin plate is pasted and dried slowly, so that the leather plate is stuffy or mouldy. < /p >
< p > (thirteen) when the fresh skin of the oil burning plate is hot, the fat in the skin plate melts and penetrated into the middle of the skin fiber, and the grease releases certain heat during the oxidation process, resulting in irreversible shrinkage and denaturation of the skin plate and skin plate gelatinization. The surface of the oil burning board is blackened, and there is a layer of grease stain. When the light weight is made, the leather plate is hard and the weight of the raw leather is broken ninety percent off. < /p >
< p > (fourteen) when the skins are over folded or heavily pressed, the skin plates of the broken plum are easy to crack or break. When making the fur, the extension and tensile strength of the skin board are obviously reduced. < /p >
< p > (fifteen) the storage time of tangerine peel is too long. After high temperature in summer, the fat is degeneration in the skin, the skin plate is oily, the luster is dark, and the surface of the board is mostly covered with yellow and red oil, and the luster of the plush is dull. During the process of making fur, the physical properties such as extensibility and tensile strength of the leather plate are reduced, and the luster of the plush is darkened. < /p >
< p > (sixteen) when the pest is poorly preserved, the skin is eaten into small holes or hairs. < /p >