Grade classification of leather

How to classify the grade of leather

Before we start to talk about cowhide, we should first talk about the problem of leather and leather. many people are vague about this concept. now many people often refer to leather as leather and artificial leather as leather. this statement is incorrect and not rigorous. Skin refers to the state of collagen fibers when they are still in the animal body (chemical structure, without any treatment); leather refers to the physical and chemical treatment of animal skin to remove useless components from the skin. and change the chemical structure of the collagen fibers of the skin, which is different from its state on the animal body. Leather is soft and flexible in dry state and not perishable in wet state. Leather is the raw material of leather, and leather is made of leather. Now the leather is a fixed term, which refers to the chemically treated leather. now some people refer to the natural leather as the leather and the non-natural leather as the leather in order to distinguish between natural leather and synthetic leather.

Cow leather (Leather) is the most commonly used natural raw material, accounting for 2 beat 3 of the world's total leather production, of which 2 prime 3 is used to make leather shoes and the rest is used in processing clothing, bags and furniture. The type, origin, age, sex, feeding condition and mode, climate, area, thickness, weight grade, fat content, sweat glands and blood vessels, as well as the density of hair, etc., all directly affect the price of cowhide and the performance of the products.

According to texture.

Cowhide can be divided into multiple layers (up to 8 layers), the outermost layer is the first layer skin, the quality is the best, followed by the second layer skin, its strength, elasticity and air permeability are not as good as the first layer skin.

The first layer skin (Kraft first layer) is cattle, sheep and pig skin with grain epidermis, with natural scars and blood tendons and other primitive skin features, and occasionally knife wounds in the processing process and belly parts with very low utilization. The head skin is composed of a dense and thin fiber layer and a slightly loose excessive layer closely connected with it, with good strength, elasticity and technological plasticity.

The two-layer skin (split leather) is obtained by cutting the layer with a skin machine, which is the second layer of loose fiber tissue, that is, the lower layer of the dermis. Made by spraying chemical materials or covered with thin film, the two-layer skin has only a loose fiber tissue layer, which can only be used to make leather goods after spraying chemical raw materials or polishing. it maintains the characteristics of natural elasticity and process plasticity, but the strength is poor.
Recycled skin (regenerated leather) is made by crushing the waste skin and scraps of dermis of all kinds of animals and blending chemical raw materials. Its surface processing technology is the same as the shaving leather and embossed leather, which is characterized by neat edges, high utilization rate and low price, but the leather body is generally thick (not thick) and poor strength.
The above kinds of leather are often used to make bags and leather seats in cars. However, the first layer of cowhide used in the car must be a very high-end car, for example, the BMW 5-Series is only used by high-equipped personnel, and the domestic cars are almost all recycled leather (not black-hearted, but can not use good materials if the price cannot be raised). General furniture sofas are made of recycled leather or two layers of leather. Leather shoes use less recycled leather (because of poor strength) unless extremely cheap or used for local collage.

Surface quality.

According to the surface quality, cowhide can be divided into full-grain flour skin, half-grain flour skin, shaved skin and so on .

Full-grain leather is divided into soft leather, wrinkled leather, positive leather and so on. It is characterized by complete retention of grain, clear, small, compact pores, irregular arrangement, plump and meticulous surface, rich elasticity and good air permeability, so it is a kind of high-grade leather. The leather products made of this cowhide are comfortable, durable and beautiful.
Half-grain cowhide is called half-grain cowhide because it is processed and polished into only half of the grain in the production process. Maintain part of the style of natural leather, pores flat oval, irregular arrangement, feel hard, generally choose poor grade raw material skin. So it belongs to middle-grade leather. Because of the particularity of the process, there is no disability and scar on the surface and the utilization rate is high, so the finished products are not easy to deform, so they are generally used for products with larger area.
The characteristic of the shaving leather is that the surface is flat and smooth without pores and skin lines, in the production, the surface grain is slightly modified, a layer of colored resin is sprayed on the leather, the surface texture of the leather is covered, and then the water-based transparent resin is sprayed. In fact, it is a "facelift" on the natural leather surface with disability or rough. This kind of leather has almost lost its original surface state, and the pattern is processed and unnatural.
Smooth cowhide belongs to the category of shaved cowhide. Because the surface brightness is different, there are two kinds of foggy cowhide and bright cowhide. The foggy cowhide surface does not shine. The bright-faced cowhide uses a colorless resin with high brightness and good light transmittance in the bright layer, and the following color appears through him. Its leather surface is bright and dazzling, showing a gorgeous style, which is the popular leather of fashion leather goods.

Cattle of different sizes:

Fetal cowhide, taken from calves born 1-30 days old, is the best layer of cowhide, with tender and slippery leather, moderate thickness, clear tread pattern, good feel and good elasticity. Fetal cowhide is a full-grain leather in natural leather. The pores are small, the distribution is uniform and compact, the grain is fine, the leather surface is plump, bright, the epidermis is thin, the tissue fiber of the skin is compact, the thickness is uniform, the skin plate is soft, and the feel is solid, elastic and breathable.
Calfskin (Calf/Calfskin Leather), calves under two years old, have smaller pores, stronger pulling force but higher price. Calfskin is a high-grade breed of cowhide because of its small or clear pores. The so-called calfskin is slaughtered when the cow is young. Each piece of cowhide is no more than 15 square feet in size and the leather is soft and smooth. Calf leather is one of the best raw materials for making shoe upper leather, but calves are more difficult to process than adult cattle, which is, of course, the reason why the price of this kind of leather is so high. Calf leather is tender and slippery with moderate thickness, clear tread pattern, good feel and good elasticity. Then there is cowhide, which is not as good as calfskin in color and feel.
With regard to cowhide identification, what kind of cowhide is calfskin? Take a new cowhide product and curl it slightly. The more delicate and uniform the wrinkled lines are, the more tender and slippery the leather is and the younger the cow is.
For the problem of taking leather to make shoes, cowhide is the best in the leather of the back, the second near the abdomen, and the worst in the shoulder and neck. A good shoe factory only takes the best part, and the worse shoe factory will make use of it. The upper (such as the head in front of the triple joint) is the best, and other parts are not as good as the upper. If it is a high-end brand generally do not have to worry too much about the use of materials, let alone customization. In the use of materials will pay attention to, they have a principle, the same pair of shoes with the same piece of leather similar parts, leather surface with symmetrical skin, uniform thickness, no obvious difference, fiber thickness and fiber density are the same, a good shoe factory will have a relatively higher scrap rate.