Essential materials for leather products. Among them, cowhide, sheepskin and pigskin are the three major types of leather used in tanning. The dermis is divided into two types: the top layer and the second layer.
(1) The top layer skin is a cow, sheep, pig skin, etc. with grain surface, natural scars and blood scars on the leather surface, occasionally knife wounds during processing and intestines with extremely low utilization rate. The imported top layer skin also has the numbering of the cattle. Full grain skin can distinguish the animal skin from the pore size and density. There are many types of cowhide, such as cow hides, meat cowhide, grazing cowhide, cow skin, bull hide, uncastrated bull hide and castrated bull hide. In China, there are also yellow cowhide, buffalo leather, yak leather and yak leather. Among them, the pores of buffalo are thicker and sparse; the yellow cowhide is thinner and denser than the pores of buffalo. The pores of the sheepskin are finer and denser and have a slight slope. There are two main types of sheep skin and goat skin. The rule of pigskin due to long hair is the distribution of 3~5 roots, so it is easy to distinguish. Generally, pigskins are artificially raised, and wild pigskins are also known. The famous wild boars are more obvious. Pig skin pores and grain characteristics, due to its special collagen fiber structure, can be processed into very soft garment leather or glove leather, which is of high value. In addition, ostrich skin, crocodile skin, short nose crocodile skin, lizard skin, snake skin, bullfrog skin, sea fish skin (shark skin, squid skin, squid skin, squid skin, pearl skin, etc.), freshwater fish skin ( There are grassy fish, squid skin and other scaly skins), hairy fox skin (silver fox skin, blue fox skin, etc.), wolf skin, dog skin, rabbit skin, etc. are easily identifiable, and can not be made into a two-layer skin.
The first layer of skin is directly processed from the raw skin of various animals, or the skin of cattle, pigs, horses, etc., which are thicker in the skin layer, is cut into two upper and lower layers, and the upper part of the fiber structure is processed into various heads. Layer skin.
(2) The second layer of skin is a loose layer of fibrous structure, which is processed by chemical spraying or coating with PVC and PU film.
Therefore, an effective method for distinguishing between the top layer and the second layer is to observe the fiber density of the longitudinal section of the skin. The top layer is composed of a dense and thin fibrous layer and a slightly loose excess layer which is closely connected thereto, and has good strength, elasticity and process plasticity. The second layer of leather has only a loose fibrous tissue layer. It can only be used to make leather products after spraying chemical materials or polishing. It maintains certain natural elasticity and process plasticity, but its strength is poor, and its thickness requires the same layer. The same skin.
There are also a variety of leathers used in today's popular production. The leather processing techniques are somewhat different, but the method of differentiation is the same. Here are a detailed description of the various leathers that have been leather-finished:
1. Water-stained leather: refers to all kinds of soft skins that are dyed with various colors such as cows, sheep, pigs, horses, deer, etc., which are dyed on the drums and glazed.
2, open edge bead skin: also known as foil leather, is tossed in two along the spine, and repaired the loose wrinkles and the top layer of the limbs or the two layers of open-edge cowhide, on the surface of the fit It is made of various PVC, metallic, fluorescent pearl, illusion, or multi-color PVC film.
3, patent leather: leather with two layers of leather blanks after spraying various chemical raw materials, calendered or matt processed.
4, shaved skin: is a poor first layer of skin billet, the surface is polished, grinding off the surface of the scars and blood scars, sprayed with a variety of popular color leather, pressed into a grainy or glossy effect of the skin.
5, embossed leather: generally use shaved skin or open edge beads to suppress a variety of patterns or patterns. For example, crocodile pattern, lizard pattern, ostrich skin pattern, python skin pattern, water ripples, beautiful bark pattern, lychee pattern, imitation deer pattern, etc., as well as various stripes, grids, three-dimensional patterns or reflect various brands. Image of creative patterns, etc.
6, printing or stencil: the same material as the embossed skin, but the processing is different, is printed or burned into a variety of patterns or patterns of the first layer or two layers of skin.
7. Matte leather: Polish the leather surface, and rub the grained scar or rough fiber to expose the neat and evenly woven leather fiber structure and then dye it into various top colors or Yan Yan?
8, suede: also known as suede, is the surface of the skin is polished into a velvet, and then dyed a variety of popular colors of the first layer of skin.
9, laser skin: also called laser skin, citing laser technology on the leather surface etching a variety of patterns of ** leather varieties.
Second, the reclaimed skin: after the pulverization of various animal skins and leather scraps, the processing of chemical raw materials is processed. The surface processing technology is the same as that of the leather, the embossed skin, which is characterized by the neat edge of the skin, high utilization rate and low price; but the skin is generally thick and the strength is poor, and it is only suitable for making the cheap briefcase and the trolley bag. The ball-shaped sleeve and other shaped craft products and flat-priced belts have uniform fiber structure in the longitudinal section, which can recognize the solidification effect of the mixed fibers of the fluid.
Third, artificial leather: also known as imitation leather or rubber, is a general term for artificial materials such as PVC and PU. It is made of PVC or PU foaming or laminating on various fabrics or non-woven fabrics. It can be made according to different strength, wear resistance, cold resistance and color, luster and pattern. The pattern and the like are required to be processed, and have the characteristics of various colors, good waterproof performance, neat edge width, high utilization rate and low price compared with leather. However, most of the artificial leather cannot have the effect of leather and its elasticity; its longitudinal Cut into the surface, you can see tiny bubbles, cloth or skin film and dry and rayon. It is a class of materials that have been extremely popular since the early days and is commonly used to make a variety of leather products, or parts of leather materials. Its increasingly advanced manufacturing process is being widely used in the processing of two-layer leather. Nowadays, artificial leather, which is very similar to leather, is produced on the market. Its surface technology is extremely fibrous. It has almost the effect of leather. Its price is comparable to that of domestic top layer.
1: Identify the leather
Hand touch: that is, touch the surface of the leather with your hand. If it is smooth, soft, full, and elastic, it is the dermis; while the synthetic synthetic leather is hairy, rigid, and soft.
Seeing: the real leather surface has clear hair and pattern, the yellow cowhide has a relatively fine pores, the yak leather has thick and sparse pores, and the goat skin has fish scales.
Smell: All leather has a leather smell; artificial leather has a strong plastic smell.
Ignition: A little bit of fiber is torn off from the back of real leather and artificial leather. After ignition, all the pungent smell is made of artificial leather; any hair that smells hair is not hard.
2, identification of artificial leather and synthetic leather
With the above four basic identification methods, it is obvious to compare and identify artificial leather and synthetic leather. In addition, artificial leather and synthetic leather have the following characteristics:
a. Press the leather surface with your fingers. There is no obvious pore wrinkles. If there is wrinkles after pressing, it will not disappear naturally.
b. There is no pores on the leather surface, which is an important feature to identify the true and false leather.
c. Cut the corners to burn, taste, but not the smell of hair.
3. How to distinguish between cow leather, pig leather, horse leather and sheep leather
The types of leather vary and their characteristics and uses vary. For example, cow leather has fine surface and high strength. * It is suitable for making leather shoes and leather goods. Sheep leather is light, thin and soft. It is an ideal fabric for leather garments; pig leather has better water vapor permeability.
Pig leather: The pores on the surface of the leather are round and thick, and extend into the leather obliquely. The pores are arranged in three groups, and the leather surface has many small triangular patterns.
a. Niu leather: Both yellow cattle leather and buffalo leather are called cattle leather, but there are certain differences between the two. The pores on the surface of the yellow cattle leather are round and straight into the leather. The pores are tight and even, and the arrangement is irregular, like a starry sky. The pores on the surface of buffalo leather are larger than those of yellow cattle leather. The number of pores is higher than that of yellow cattle leather. The leather quality is slack, which is not as fine as the yellow cattle leather.
b. Horse leather: The hair on the surface of the leather is also oval, slightly larger than the pores of the yellow cattle leather, and arranged in a regular pattern.
c. Sheepskin: The pores of the leather surface are oblate, the pores are clear, and several pieces are grouped together and arranged in a fish scale.
Quality identification of leather
The cowhide can be divided into multiple layers (* can be divided into 8 layers). * The outer layer is the top layer skin, and the second layer is the second layer skin. Its strength, elasticity and breathability are not as good as the top layer skin. The car seat must use the top layer. 2. A composite skin currently on the market is a two-layered leather with a film on the surface. The surface is delicate and looks like the top layer.
From a professional point of view, the identification of leather should be judged from the aspects of odor, specific gravity, light resistance, migration resistance, atomization, thermal yellowing and abrasion resistance of automobile skin. Since most car owners do not have the expertise in this area, it is difficult to judge. It is advisable to use the following simple methods for identification. a, volume labeling method
The leather of the factory will be marked with the date of manufacture and the name of the name of the leather factory. Of course, the date of manufacture should not be too long, and leathers that have been in use for more than 3 years should be noted for mildew.
b, olfactory method
Good leather should not have a pungent taste after treatment, so too much solvent smell and paint taste is not good.
c, heat resistance method
**Because the manufacturer wants a small piece of leather material, use the cigarette head to touch the hot sample for about 2~3s, which can avoid avoiding the purchase of artificial leather products; the burning of the lighter is due to the large contact area, so the time needs to be lengthened.
d, viewing method
Under the 30 times magnifying glass, it can be seen that the outer surface of the leather is like the surface of the earth, and the hole is pitted, and the air permeability is good. Car leather needs special treatment such as abrasion resistance and light resistance, and the pores will be covered.
e, cutting method
The leather is cut transversely by the blade, and the color of the leather from the outer layer to the inner layer must be the same (the appearance is black, the inside is dark gray, it is a normal phenomenon). Pay attention to whether there is any color difference under the outer layer to avoid buying second-hand leather that is dyed or changed twice.
f. Wiping method
Wipe the surface of the leather with stain-free oil, pay attention to whether there is fading or falling off, and avoid buying secondary color-changing leather.
g, origin method
Leather is produced in all countries of the world, but the leather industry in Europe (Northern Europe, Italy, Austria, Germany, etc.) has a long history. Naturally, its leather processing level is much higher than that of low-grade Southeast Asian leather.
h, document law
The leather of the factory has clear source, origin, trademark, leather measurement project and leather use authorization and other basic information.
i, guarantee method
This is a simple way. When buying a leather chair, don't forget to ask the store if there is a guaranteed service card, to avoid buying inferior leather, to develop regular maintenance habits, and to provide permanent after-sales service. It can be described as the benefits of three things.
Identification method of dermis and fake skin
1. Finger method; press the skin with your fingers and the surface will have fine wrinkles. When the finger is lifted, the wrinkles immediately disappear into the dermis. Artificial leather and synthetic leather are free of wrinkles.
2, the water method; drop a little water on the leather, and then dry the water stains, touch the feeling of sticky sticky hands, it is the leather.
3, the perception method; take the front of the leather, carefully observe with the eyes, the leather has pores, and the artificial leather has no pores. Look at the reverse side of the leather, look for the parts without folds, if it is the base fabric, it must be artificial leather or synthetic leather.
Identification of shaved skin, split skin and regenerated skin
After folding the leather material in half, it is the cowhide that disappears immediately. The wrinkles do not disappear.