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"Several layers of leather shoes"

Dermal is the raw skin stripped from cattle, sheep, pigs, horses, deer or other animals. After tanning in leather factory, leather with various characteristics, strength, feel, color and pattern is an essential material for modern leather products. Among them, cowhide, sheepskin and pigskin are the three raw materials for tanning. There are two kinds of dermis: the first layer and the second layer.

(1) The first layer of skin is cattle, sheep and pig skin, with grain surface, natural scars and traces of blood tendons on the skin surface, occasional knife wounds during processing and extremely low utilization rate of belly. The first layer of imported leather also has the number plate of the ox. Full grain leather can be distinguished by pore thickness and density. There are many kinds of cowhide, including cowhide, beef cowhide, grazing cowhide, bull cowhide, castrated bull cowhide, castrated bull cowhide and so on. In China, there are cowhide, buffalo hide, yak skin and yak skin. Among them, the pores of buffalo hide are thicker and thinner; The pores of cowhide are thinner and denser than buffalo hide. The pores of sheepskin are fine, dense and a little inclined, mainly sheepskin and goatskin. Pigskin is easy to distinguish because the rule of long hair is 3~5 small pieces. Generally, artificially raised pig skins and wild boar skins are the famous South American wild boar. This kind of wild boar skin has obvious pore and grain surface characteristics of pig skin. Because of its special collagen fiber structure, it can be processed into very soft garment leather or glove leather with high value. In addition, ostrich skin, crocodile skin, crocodile skin, lizard skin, snake skin, bullfrog skin, marine fish skin (including shark skin, cod skin, sole skin, eel skin, pearl fish skin, etc. ), freshwater fish skin (including scaly fish skin such as grass carp skin and carp skin) and hairy fox skin (silver fox skin and blue fox skin, etc. ).

The top skin is directly processed from the original skins of various animals, or the skins of cattle, pigs, horses and other animals with thick skins are cut into upper and lower layers, and the upper layer with tight fiber structure is processed into various top skins.

(2) The second skin consists of two layers with loose fiber structure, and is processed by spraying chemical materials or covering PVC and PU films.

Therefore, an effective way to distinguish the first skin from the second skin is to observe the fiber density on the longitudinal section of the skin. The top layer is composed of a dense and thin fiber layer and a slightly loose transition layer closely connected with it, which has good strength, elasticity and process plasticity. The second layer of leather has only a loose fibrous tissue layer, which can only be used to make leather products after spraying chemical raw materials or polishing. It maintains certain characteristics of natural elasticity and process plasticity, but its strength is poor, and the thickness requirement is the same as that of the first layer of leather.

The so-called dermis has only a first layer and a second layer. To put it bluntly, leather goods made of the first layer of leather are directly processed from the original skins of various animals. Relatively speaking, the second skin is a two-layer part with loose fiber structure, which is treated by spraying chemical materials or covering PVC and PU films. The quality is naturally worse than the first leather, and the price is cheaper than the original leather. The top layer and the second layer are also divided into thickness and advantages and disadvantages. Not all the top and second layers have the same mass. The second floor with good quality is sometimes even more comfortable and durable than the low-grade top floor, which requires you to cultivate a critical eye, which is basically indistinguishable to the naked eye, mainly depending on the seller's conscience.

In addition, recycled leather is made by grinding waste skins and leather scraps from various animals and mixing chemical raw materials. Its surface processing technology is the same as leather trimming and embossed leather, which is characterized by neat edges, high utilization rate and low price. However, the leather body is generally thick and the strength is poor, so it is only suitable for making cheap briefcase, trolley bag, club cover and other shaped products and cheap belts.