What is tanned cattle hide? The technological qualities of reindeer skins depend on the sex of the animals. Tanning leather at home

The weight of hides is not only a quantitative indicator, but also serves as a criterion for classifying raw materials into sex-age groups and groups based on weight of hides. Thus, the outgrowth (calf skin) has a mass of up to 10 kg, and the half-skin (calf or bull skin) weighs from 10 to 13 kg. Within sex and age groups (cawl, bull, etc.), skins are divided by weight into light, medium and heavy. The weight of paired skins is determined in a cooled state, and washed paired skins - only after draining water from them, which lasts for 2 hours. Weighing is carried out on working scales, checked once a year by the local body of state supervision of standards and measuring equipment and bearing the appropriate mark. Weighing accuracy is set to 100 g, with 50 g or more taken as 100 g, and less than 50 g discarded.

The mass of the skin is determined in its pure form, that is, without weighting agents: trimmings of meat and fat, clots of blood and dirt, bulk, ice and salt. They are given a discount on the weight of the skin. The thin layer of meat on the skins of cattle - "magpie meat" - is not considered a weighting agent. The size of the discounts is determined by testing several skins from the batch. By weighing them before and after the ritual, the mass of the removed weighting agents is determined by the difference in the mass of the skins. The average value for one skin is calculated and an adjustment is made for the weight of the skins with weighting agents. It should be taken into account that skins are considered dressed if the presence of weighting agents (except for salt and moisture) does not exceed 200 g on small skins, and 500 g on large skins. Excess salt is separated by shaking the skin. A discount is made for the presence of excess moisture in canned skins, and for a lack of moisture or over-drying, an allowance is made for the weight determined during weighing. To do this, you need to determine the percentage of salt. This need arises due to the fact that canning hides is accompanied by loss of moisture, which turns into brine during salting or evaporates during drying. Reducing the weight of the skin when preserving with salt is called salting, and after drying - shrinkage. The initial mass, taken as 100%, is the mass of paired raw materials. The ratio of the weight of a fresh skin to the weight of a preserved skin is called the curing or shrinkage coefficient.

The weight loss of skins depends on the method of canning, and since it can be different, the standard establishes coefficients for converting the weight of a canned skin into an unpreserved one, i.e., a steamed one. The normal weight loss is 5% for frozen skins, 13% for wet-salted skins, 50% for dry-salted skins, and 60% for fresh-dry skins. Normal weight loss refers to the loss of weight of a properly preserved hide in comparison with its original weight. But often the actual mass loss is less or greater than provided by the indicated coefficients. The amount of weight loss depends not only on how correctly the skins are preserved, but also on the conditions under which they were preserved and stored. So, if a skin preserved by the wet-salting method is kept in a room with a high temperature for a long time, it will lose more weight than prescribed by the standards, and if the skin was preserved in a cold room, the loss will be significantly lower than normal.

The percentage of salt is determined according to GOST 13104-77 "Raw leather leather. Methods for determining salt and net weight." According to this standard, usol can be determined by both organoleptic and analytical methods. The essence of the organoleptic method is viewing and palpating the raw materials. Using the analytical method, salt is determined by the moisture content in the preserved skin. To do this, from different topographical areas of the skin under study: flaps, collar, rump, one sample measuring 2x1 cm, with a total weight of 6-9 g, is cut out or cut out. The sample is divided into two parts, each weighing 3-4 g, and crushed into pieces 2-3 mm wide, 4-5 mm long and dried in a drying cabinet to a constantly dry mass. Samples of cattle skins are dried at a temperature of 170-180°C, raw pork, sheepskin and goat skins - at 135-137°C. Percentage humidity is determined using the following formula:

where m is the mass of the sample before drying,

m 1 is the mass of the sample after drying.

The arithmetic mean of two parallel determinations is taken as the final test result.

The percentage of salting of cattle hides is determined by the moisture content in accordance with Table 24.

The mass of skins, taking into account salting, is determined by the formula, kg:

where m f is the actual mass of the skin, kg;

In B - curing of skins at normal humidity of 46-47%;

U f is the actual curing of the skin, %.

For example, the weight of wet-salted canned cattle hide without weighting agents is 25 kg. Normal brine is 13%, actual brine is determined at a humidity of 42% as 20.2%.

Using the formula, we get the result:

Consequently, as a result of excessive salting of raw materials, excess salt was obtained, which amounted to 7.2%. A premium is placed on it, since the skin has lost more moisture than expected during normal canning. The additional weight of the skin in this case is 2.3 kg.

Analytical method The definition of brine is used mainly only in controversial cases when the receiver disagrees with the data of the supplier of raw materials - a collective farm or state farm. Simple equipment used to analyze the moisture content of hides (brine): analytical balances, drying cabinet heated to 200°C - allows you to determine this indicator when the raw material is accepted by the procurer directly on a collective farm or state farm.

Organoleptic method Determining the percentage of brine consists of viewing and palpating the skin. Organoleptically, the degree of brine of wet-salted (non-brined) raw materials can be divided into three categories: normally salted, under-salted and over-salted. Normally salted the skin is dense, elastic, elastic. The flesh after scraping with a knife is gray in color (in skins washed with water, the flesh is milky white), without watery spots. The hair side of the skin is moist, but without its excess (moisture does not come out when pressed with your hand). Cut meat, including “magpie”, faded, light yellow in color. The degree of salting of such skins is 12-14%.

Undersalted the skin is loose (soft), low-elastic, the inside after scraping with a knife is bluish-red in color, very watery. The hair on the skin is damp. The moisture is squeezed out abundantly when pressed with the edge of the palm. The cuts of meat are purple-blue-red in color. The degree of salting of such skins is 6-8%.

Over-salted the skin has increased density and elasticity, the inner part is dry on half the area, and has normal humidity on the rest. The color of the flesh after scraping with a knife is milky white with strong yellowness. The hair is dry on half the area of the skin. The meat cuts do not differ in color from the flesh. The degree of salting of such skins is 18-20%.

The practical application of the organoleptic method of the degree of salting comes down to determining the mass of the skin. If the skin is under-salted, it will weigh more than a normally preserved one. In this case, you need to make a discount from the actual weight.

For example, the skin of a bull weighing 30 kg has an organoleptic assessment of 7%. The scoring weight of this skin will be as follows:

i.e., from the weight of the skin (30 kg), a discount of 1.9 kg is made for under-salting.

In a simplified, but less accurate, approximate way, the calculation is done as follows: the difference between the brine rate (13%) and the actual brine (7%) is taken. It will be 6%, the discount for under-salting is 1.8 kg (30 kg × 6%), The qualifying weight of this skin will be 28.2 kg (30-1.8).

The mass of over-salted skins is covered in a similar way with a calculated cape of over-salting.

All this applies to raw materials preserved in compliance with established rules. Incorrectly preserved raw materials, or fresh raw materials that have lost a significant part of their moisture due to untimely delivery after removal from the animal carcass, are assessed as follows.

Fresh-dry and dry-salted skins should be dried. If this cannot be done, then the under-dried skins are sold as fresh-dry or dry-salted with a discount on moisture content. Steamed raw materials that have lost a significant portion of moisture are accepted as steamed with an addition of the corresponding mass of lost moisture.

Example 1. In a properly preserved dry-salted skin, every 100 kg of mass contains 20 kg of moisture and 80 kg of dry matter. If the skin contains not 20, but 30% water, then 100 kg of dry matter will contain not 80, but only 70 kg. A discount of 12.5% (80-70)×100:80 should be made on the weight of such a skin. Example 2. In a pair of skins, every 100 kg of mass contain 65 kg of water and 35 kg of dry matter. If the skin, which has dried out without being preserved, contains not 65, but 50% moisture, then to determine its mass in paired form, you need to apply a coefficient of 1.43 (50:35). The weight of the dried skin is multiplied by 1.43.

The approximate weight of the fresh skin of cattle can be determined at the rate of 7% of the live weight of the animal with a discount for the content of the gastrointestinal tract of 3%.

For example, a bull weighed 300 kg. The discount will be 9 kg. The mass of the hide will be (291 × 7): 100 = 20.37 kg, or after rounding 20 kg.

After determining the mass, they begin to determine the type of skins. First of all, you should separate the skins of the outgrowth from the half-skin, since the difference in prices for these types of raw materials is 25%. Outgrowth is a more expensive raw material than half-leather. Its mass is up to 10 kg in terms of mass in pairs; the half-leather has a mass of more than 10 kg. Cattle skins weighing over 13 kg are divided not only by weight, but also depending on gender: cow, bull, bull. Then the weight of the skins of large leather raw materials of all types of animals is determined, dividing cow meat and camel into light, medium and heavy, and bull, bull, horse meat into light and heavy. The skins of young cattle, horses and camels weigh up to 10 kg.

Determination of size (area) sheepskin, goatskin, pig and deer skins. The size is determined by the occupied area. The area of the hides is measured with a wooden meter in square decimeters, by multiplying the length of the hide by the width. Measurements are carried out with an accuracy of 1 dm 2, while values from 0.5 to 1 dm inclusive are taken as 1 dm, and less than 0.5 dm are discarded. Before measuring, the sheepskin is spread out on the table, straightened out from folds, wrinkles and other irregularities without stretching it in length and width. Measuring certain types of skins has its own characteristics.

The length of sheepskins and goatskins is measured along the ridge from the upper edge of the neck to the base of the tail, and for fat-tailed sheepskins - to a conventional line connecting the lower depressions of the hind legs, defining the base of the tail. The width is measured in the middle part of the skin along a line drawn 3-4 cm below the lower depressions of the front paws (Fig. 3 and 4). Stretch-dried sheep and goat skins are accepted with a 10% discount. Signs of stretching are protrusions along the contour of the skin in places of stretching.

The length of pork skins is measured along the ridge from the upper edge of the neck to the tangent line to the lower hollows of the hind legs. The width is determined in the middle part of the skin along a line 8-10 cm below the edge of the lower cavities of the front paws (Fig. 5). The length of the pork rump is measured along the ridge from the top to the bottom edges of the skin, and the width is measured in the middle.

The length of deer skins is determined from the front edge of the neck to the base of the tail. Width is measured differently in young and mature deer. The width of the skins of young animals is measured along a line 3-4 cm below the lower edge of the lower cavities of the front paws. For the skins of adult deer, the width is measured along a line connecting the midpoints of the outer edges of the front groins. Skins dried with stretching are accepted with a 10% discount on the area. Stretch is determined in the same way as for sheep skins.

The area of fur pelts of cows and foals, lambs (including astrakhan) and kids' skins is determined by multiplying the length from the base of the neck to the base of the tail by the width in the middle of the pelt.

The area of the skin can be measured on a special decimeter tablet. Using a tablet eliminates the need for any calculations, simplifies and speeds up determining the size of the cord, but requires certain skills.

The tablet is a plywood sheet or a rectangular wooden table with an area divided into squares. Each square is equal to 1 dm 2. On the right side of the tablet, from bottom to top, there are 12 squares with numbers from 1 to 12 printed on them. The bottom row of squares consists of numbers from 1 to 10. Each subsequent row of horizontal squares increases by 10 units and so on up to 120.

The area of the skin is determined by the number of squares it covers. To measure, the skin is placed on the tablet with the flesh side up so that the base of the tail is aligned with the lower edge of the tablet, and the right reference point for the width of the skin (for sheepskins it is 3-4 cm below the lower depressions of the front paws) is aligned with the right edge of the tablet. The hide area indicator is determined by the square on which the projections of the upper reference point for the length and the left reference point for the width of the hide intersect (Fig. 6).

Rice. 6. Measuring the area of skins on a decimeter tablet. The area of the sheepskin is 54 dm 2

If the area of the skin cannot be measured due to improper preservation (frozen or dried in a lump or with large folds), then the size is determined by the weight of the raw material, based on the following coefficients. Mass of 1 dm 2 is equal, g:

Consequently, to determine the size of a lump or highly folded skin, its mass in grams is divided by the coefficient established for it and the area in square decimeters is obtained. For example, frozen ball wool sheepskin has a mass of 3.6 kg. With a mass of 1 dm 2 40 g, the area of the sheepskin will be 90 dm 2 (3600-40).

In the practice of handing over and accepting sheepskins and goatskin, if it is carried out directly on the farm, sometimes it becomes necessary to check the correctness of the measurement of the area of the hides. To do this, you can use data from weighing animals before slaughter. The approximate size of sheep and goat skins is determined in square decimeters based on every 1 kg of live weight (minus 3% for the content of the gastrointestinal tract) 2 dm 2 of skin area. For example, the live weight of a sheep is 45 kg, the size of the 3% discount is 1.35 kg, the size of the sheepskin (43.65 kg × 2 = 87.3) will be 87 dm 2.

After determining the mass or area of the hides, their type and production purpose are determined in order to find out by what standard the raw materials need to be sorted. From the skins of young cattle and horses, the skins of mucus, milk and foal are distinguished. Such skins can be either fur or leather raw materials, depending on the condition of the hair. If the hair length exceeds 2 cm for foal skins, and 2.5 cm for calf skins, or there are defects above the norms provided for in the standards for feather and foal fur skins, then they are classified as raw hides. From the skins of sheep and goats, the skins of lambs and kids with an area of no more than 18 dm2 are isolated. They are sorted according to the standard for undressed lamb and kid skins. If their area is more than 18 dm 2, then they should be sorted as fur and fur sheepskins, and goat skins - as raw hides. The suitability of sheepskin for use in fur and fur coats is preliminarily determined in accordance with the requirements of the standards for these types of raw materials.

Cow hide is the most valuable raw material for the production of high quality leather. However, the final characteristics of the resulting product depend entirely on the correctness of the dressing procedure. Only then can you be confident in the strength and durability of the product. Read about the intricacies and technology of processing cattle hides at home further in the article.

Technology for processing (dressing) cattle skins at home

Leather production has a rich history and tradition. Even primitive people mastered the basics of hide dressing, using improvised means to obtain soft, smooth material for sewing clothes. And modern fashionistas cannot imagine their interior and wardrobe without leather goods, which never go out of fashion, are stylish and practical.

However, to obtain a quality product, a certain skill is important. Let's look at the process of processing skins step by step.

Did you know? The word “skin” in ancient times sounded like “goat” and specifically meant the skin of a goat. Subsequently, the meaning of this lexical unit expanded and began to denote the body cover of both any animal and human.

Preparation

At home, when preparing the skin for dressing, it is important immediately after removing it from the carcass:

remove fatty meat residues;
spread on a flat surface, wool side down, to cool;
generously sprinkle with coarse table salt without iodine (about 3-4 kg is required for one cow skin; this is done when the raw material has cooled);
Dry the skin for several days until it becomes dry and stiff.

Skin sprinkled with salt

Soaking

To obtain soft, high-quality leather, cowhide is soaked in 2 stages:

First, the raw materials are immersed in clean water for 4 hours.
And after that, for 12 hours it is kept in a saline solution, which is prepared at the rate of 20 g of salt per 1 liter of water. Please note that over time the skin will begin to swell, so experienced experts advise preparing 8 liters of liquid for each kilogram of it.

Soaking is considered to be of high quality when after it the subcutaneous layer is easily removed from the wet-salted workpiece. If difficulties arise, the raw materials require additional aging in a saline solution.
To prevent bacterial infection of skins, tanners advise using a solution based on salt and furatsilin However, you should not leave it in this form for a long time, because the material may deteriorate. Experienced tanners recommend adding 6 tablets of furatsilin to each 10-liter bucket of water to prevent bacterial infection of the skins.

Important! The harvested raw materials must be without cuts, since even small punctures reduce its quality.

Mechanical degreasing, fleshing of hides

At this stage of dressing, it is important to carefully remove the subcutaneous fat deposits of the slaughtered animal. Some craftsmen do the fleshing manually, while others prefer to use a special mechanical device, the design of which resembles a rotating disk with sharp edges.

However, without some experience it is dangerous to operate such a device, since incorrectly cut hair follicles will affect the quality of the skin. To get a good result, experts advise removing the fat layer evenly, starting from the tail, with smooth movements from the axial center to the periphery.

Washing

After degreasing, the cowhide must be washed in warm water. To do this, it is recommended to use a soap solution. It is prepared in a ratio of 10 g:1 l. It is best to use laundry soap; soda ash is an alternative.

Did you know? In the 17th–19th centuries, binding made of human skin was used to decorate some books. Most often, treatises on anatomy were decorated in this way. Copies of criminal cases of executed criminals could be bound with leather. And sometimes such books were made from the skin of the deceased according to their will.

Pickling (or pickling)

In order for the prepared skins to change their structure, they are kept in a special vinegar-chlorine solution. For this purpose, acetic acid must be dissolved in water at a concentration of 0.15% and liquid sodium chlorine at a concentration of 0.04%.

Pickling involves periodically stirring the resulting composition after dipping the raw materials into it. Its exposure should last for 12 hours, until white stripes remain on the folds of the material when squeezed.
At this stage of home leather dressing, pickling can be replaced by fermentation. Its technology consists of soaking washed raw materials in an aqueous suspension of oatmeal or barley flour. The solution is prepared from warm water, adding 60 g of salt and 100 g of flour for each liter.

After mixing all the ingredients, you can dip the skin into the resulting mixture, but do not leave it unattended for a long period. Experienced craftsmen advise constantly monitoring the fermentation results, since over-cured material is unsuitable for further processing.

Did you know? The reflex that leads to the appearance of goose bumps is inherited from animals. . The muscles of the hair follicles contract and lift the hairs, causing the animal's fur to stand on end. When reacting to cold, this helps to retain body heat longer; when reacting to danger, it makes the animal more massive and terrifying. In humans, during the process of evolution, there is little hair left on the body, and this reflex has no practical meaning.

Tanning

After these manipulations, the cow hide must be tanned. The technology of this process involves soaking the raw materials for six hours in a special solution of chromium oxide. When preparing it, maintain the proportion of 1.5 g of active substance for every liter of warm liquid. After placing the skin into the resulting mixture, it is important to stir it periodically.
Some livestock farmers carry out the tanning procedure using:

oak bark;
stems of stinging nettle;
willow branches;
alder biomass.

All components need to be finely chopped and measured in equal parts of 250 g. After that, prepare a saline solution in a ratio of 1: 60 and add the plant mixture to it. The liquid must be boiled and simmered over low heat for half an hour. Then the finished broth is filtered, allowed to cool slightly and the cow skin is soaked in it for 6 hours.

Zhirovka

At this stage, the technology for home tanning of cattle leather involves the preparation of a special emulsion.

It is done by adding the following components to water heated to 45–50 °C:

laundry soap shavings - 200 g;
ammonia - 10 g;
any fat - 80 g.

Mix everything thoroughly, and then carefully treat the inner side of the skin with the resulting product. This is done using a soft brush or swab. After fattening, the hide blanks are stacked and left for 24 hours.

Drying skins

At the final stage, the oiled skins are stretched onto a wooden grid or flooring so that the flesh is located on top. You should not overdo it in this matter, because after so many treatments the skin may tear, but the tension should be noticeable.
During the entire drying period, it is recommended to take the workpiece outside every day to a shady place for ventilation. When the skins in the center zone on the inner side become elastic and dry to the touch, they can be removed. After that, it is recommended to spread the skin on a flat surface and clean the inside with a metal brush.

Did you know? The polar bear has black skin under its fur. The bristles of the fur coat themselves are transparent and hollow, so in different conditions the color of the bear can vary from white to yellowish. In hot countries in captivity, a polar bear may even turn green if algae begins to grow in the bristles.

This will make the material lighter and softer. In this case, sharp jerky jerks are unacceptable. The tool should move smoothly and evenly, which will give the inside of the skin a “suede” velvety feel. Then, until it is finally ready, it is sent to dry for another 2 days.

Video: skin processing

Classifications of cattle skins

Experienced livestock breeders who have mastered the technology of home-dressing cattle skins distinguish several types. Each of them differs in the level of strength and nuances in processing. Let's take a closer look.

Important! If the technology for tanning leather at home involves the use of any acids, remember that ordinary soda will help neutralize their effect. Please note that during the chemical reaction there will be a lot of foam, so choose rooms with good ventilation for work.

This is calfskin, the characteristic feature of which is faded and matted primary wool. The raw materials for the product are animals from birth until the end of milk feeding.

CLASSIFICATION OF HAND RAW MATERIALS AND ITS CHARACTERISTICS

AND PROPERTIES OF NATURAL FUR, LEATHER AND OTHER MATERIALS USED IN THE MANUFACTURE OF CLOTHES AND FOOTWEAR

Leather raw materials, depending on the type of animal and weight, are divided into small, large, and pork.

Small raw materials: skins of cattle calves (skin, calf, outgrowth), camels, foals (skin, foal, litter), sheep (Russian sheepskin, steppe sheepskin), goats (steppe goat, grain, wild goat skins).

Large raw materials: skins of cattle (half-skin, bull, bull, bull, cow, buffalo, yak, elk), horses (horse skin, peredina, haz), camels, donkeys and mules, animals of other species (adult deer, walrus and etc.).

Pork raw materials: pork skins, fish, boar skins.

The procurement of raw hides is carried out in accordance with the requirements of GOST 1134-73; delivery to tanneries - in accordance with GOST 382-76.

TO small raw materials relate:

slime - the skin of an unborn or stillborn calf, regardless of weight. The area of the slug is on average 40-50 dm2, the thickness of the rump is 1.2-1.5 mm. The slime is characterized by a loose ligature of bundles of collagen fibers and a relatively large thickness of the epidermis - 3-4% of the thickness of the skin;

opoek - the skin of a calf (regardless of weight) that has not mastered plant food, with primary unshed hair. The thickness is relatively uniform over the entire area of the hide; The thickness of the rump of a pair of skins is 1.3-2.5 mm. The area of the feeding area depends on the age of the calf; The skin area of a 10-day-old animal is 70-75 dm2, at the age of 3 months it is 100-120 dm2. The thickness of the epidermis is 2%, the papillary layer is 30-35% of the total thickness of the skin. The papillary layer consists of thin bundles of densely packed collagen fibers. The reticular layer of the dermis is well developed; The connection of the bunches is dense and uniform. The coat of the opoika is characterized by shiny and soft primary hair. Relatively thin hair determines the delicateness of the leather. The quality of the feed is determined by the nature of feeding the calves. The best quality skins from milk-fed calves. The skins of calves prematurely switched to plant foods have dull, uneven hair, and when dressed, they have loose skin tissue. The skins of cows (calves) have milk lines;

outgrowth - the skin of a calf that has mastered plant food and is in the stage of changing its primary hair coat. Weight in pairs up to 10 kg inclusive, area 100-160 dm2, thickness at rump 1.5-3.0 mm. The thickness of the outgrowth decreases significantly in the direction from the rump to the collar and floors. In terms of the ratio of the papillary and reticular layers of the dermis, the density and complexity of the interweaving of the fibers of the dermis, the outgrowth approaches the skins of adult animals. On the collar and below it there are deep folds (wrinkles), often covering from 1/3 to

1/2 area of skin. Characteristic signs of the outgrowth are a formed tuft of hair on the tail, tubercles in the place of future horns, and a thicker and less uniform thickness than that of the flange.

The hair of the outgrowth, unlike the fluff, does not contain any hair shorter than 10 mm, and its long hair is heterogeneous and coarser.

TO large raw materials relate:

half-skin - the skin of a heifer or bull of transitional age (from calves to adult animals). The weight of paired skins is from 10 to 13 kg inclusive. According to the structure of the dermis, the semicutaneous approximates the outgrowth. The area of the half-skin usually ranges from 120-220 dm2, the thickness at the rump is 2.5-3.5 mm. Large fluctuations in the area and thickness of hides depend on the harvesting area, the direction of cattle breeding, breed, conditions of keeping and feeding of livestock. The skins of heifers are smoother than the skins of bulls and less furry. The mereya of a half-leather is coarser than the mereya of a sprout or a calf, but thinner and more delicate than the mereya of leather made from the skins of adult animals;

bull - the skin of a bull and castrated bull weighing in a paired state from 13 to 17 kg inclusive. The area of the skins is 200-270 dm2, the thickness at the rump is 3-4.5 mm. The bull, especially one with a thickness of more than 4 mm, is characterized by the presence of borus and camber (thin neck).

The skins of bulls of all breeds at the age of 18 months under the same conditions of detention are 10-30% heavier than the skins of castrated bulls. The skins of uncastrated bulls and the leathers produced from them are not inferior in terms of quality to the skins and leathers from castrated bulls of the same age;

bull - the skin of a bull castrated at an early age, the mass of which in pairs is more than 17 kg. There are light bulls weighing from 17 to 25 kg inclusive and heavy bulls weighing more than 25 kg in pairs. This type of raw material is harvested mainly in areas with meat-based cattle breeding. The size of the bull, its weight and thickness depend on the age and breed of the animal, conditions of keeping and feeding. Depending on the weight, the thickness of the beef ranges from 3.5 to 5.5 mm in the rump, 2.5-4.5 mm in the collar, and 2.0-3.0 mm in the floors. The area of a bull weighing 17-19 kg is on average about 300 dm 2, weighing more than 30 kg - up to 500 dm 2. In the saddle cloth, the papillary layer accounts for about 20-25% of the total thickness of the dermis, and the reticular layer accounts for about 80-75%. The papillary layer is formed by an interweaving of thin fibers and has many holes from hair follicles, sebaceous and sweat glands, fatty and other inclusions. The thickness of the epidermis in the skins of adult animals does not exceed 0.5% of the total thickness of the skin. The sparse hair coat consists of straight hair located at a slight angle to the papillary layer and lying shallowly in it, mostly evenly over the entire surface of the skin. The pattern of the measure is low-relief. The histological structure of the reticular layer in different topographic areas of the skins of adult cattle is not the same. In the saddle part of the skin, the collagen bundles have the greatest thickness, fit tightly to each other, form a diamond-shaped diaphragm, the loops of which penetrate one another and often stretch through the entire thickness of the mesh layer (plexus class I). The floor is characterized by the arrangement of tufts parallel to the surface of the skin (class V). Other topographic areas occupy an intermediate position in their structure (classes II-IV);

cowhide - the skin of a heifer or cow weighing more than 13 kg in a paired state. There are light fish weighing from 13 kg to 17 kg inclusive; medium - from 17 to 25 kg inclusive and heavy - more than 25 kg. The structure of the hair, papillary and reticular layers of the cow is close to the structure of the bull. The difference lies in less powerful bundles of collagen fibers. Depending on the age and breed, the area of the trap ranges from 200 to 450 dm 2. The thickness of the light cow in the rump ranges from 3.0-3.5 mm, in the collar 2.0-2.5 mm, in the floors 1.5-2.5 mm. The heavy cowhide has a thickness of 3.5-4.5; 2.5-3.5 and 1.5-3.0 mm. The skins of heifers are denser and more uniform in thickness than the skins of cows; they are superior in quality to the skins of bulls of the same weight. A characteristic feature of medium and heavy pits is a large area due to the small thickness and increased floor area, i.e., hollowness;

bugai - the skin of a bull weighing more than 17 kg in a paired state. Characterized by the presence of rough thickened folds on the collar. Light bull - skins weighing from 17 to 25 kg inclusive, heavy bull - more than 25 kg. The structure of the bull is characterized by thickening of the peripheral areas, and this thickening increases with the age of the animal. The structure of a bull of small mass is close to the structure of a bull, and the structure of a bull of large mass is very different from it. A significant part of the area of the bull is occupied by a collar with deep transverse folds.

The skins of buffalo, yak and elk are divided by weight into the same groups as the skins of cattle. Buffalo hides are thick, heavy and crumbly. The structure of yak skin is almost no different from the structure of other cattle skins.

For the production of leather, the skins of a wide variety of animals and even fish and birds are used. The main types of leather raw materials are the skins of cattle - cows and bulls; horse, goat, sheep, pork. Less commonly used are the skins of wild boar, deer, dogs, saigas, roe deer, yaks, buffalo, camels, sea animals and fish.

When classifying raw materials, many characteristics are taken into account, among which the main ones are: the type of skin depending on the type of animal, the mass of the skin in kilograms, the area of the skin in square decimeters, the method of preservation.

Requirements for raw hides are regulated by GOST 28425-90 “Raw raw hides. Technical conditions", GOST 28509-90 "Undressed sheepskins. Technical conditions".

The so-called large raw materials are classified by weight: cattle, horse, camel skins. Cattle raw materials are the most diverse and have a classification of types depending on the age of the animal: cow, outgrowth, half-skinned, bull, bull, cow, bull. As the animal ages, the mass, area and thickness of the skins increase.

Depending on the type of animal, the mass in a paired state or the area of the hide, raw hides according to GOST 28425-90 are divided into small, large and pork.

Small raw hides include:

calf skins: slime, calf skin, outgrowth;

camel skins: skins of young camels weighing up to 10 kg;

skins of foals: slick, foal and marking;

goat skins: steppe goat, grain goat, wild goat skins - skins of goats from the family of wild and hornless mammals: wild goat, roe deer, wild gazelle, saiga, argali (wild sheep) and musk deer.

Large leather raw materials include:

half-leather, goby, cow, light, medium and heavy;

bull, light and heavy, bull;

buffalo, yak, elk;

horse front;

horse haz;

skins of camels, skins of donkeys and mules.

Pork hides include:

pork skins - the skins of domestic pigs and hogs.

Depending on the area in the paired state, pig skins are divided into:

for small ones - from 30 to 70 dm2;

for medium ones - over 70--120 dm2;

for large ones - over 120 dm2;

In accordance with GOST 28509-90, rare-wool skins of Russian and steppe fur sheepskin (less than 1000 fibers per 1 cm2), with wool flow in an area of more than 50%, with deep burrs throughout the entire area of the sheepskin, lying at a distance of 1. 5 cm or less from the base of the hair or with heavily felted hair; skins of adult Romanov sheep with an area of less than 35 dm2 and white sheep with an area of less than 24 dm2 with wool flow on an area of more than 50%, with heavily felted wool, with deep burrs on an area of more than 25% of the sheepskin area, lying on more than half the length of the wool and cannot be removed .

For the production of leather in small quantities, the skins of deer, beluga, sea lion, northern seal, Far Eastern seal, as well as whale hides are used.

Cattle hides have a dense structure. The epidermis is thin, the papillary (thermostatic) layer in the skins of young animals is 45-50%, in adults - 30-35% of the thickness. The thickness of this layer varies over the area of the skin and on the back reaches 30-35%; on floors - 50% of the thickness of the dermis.

Cattle hides are divided into groups of small and large raw materials.

Small raw cattle weighs up to 10 kg. These include the following types:

Slimes are the skins of unborn or stillborn calves that are not suitable for fur production. The area of the skin is 40-50 dm2, the thickness at the rump is 1.2-1.4 mm. The skin has a rather thick epidermis (3-4% of the skin thickness). Such small and thin leathers are used for the production of clothing, haberdashery leather and chrome leather for shoe uppers.

Opoek - the skins of suckling calves that have not mastered plant food, with primary non-shedding wool (up to 3 months, regardless of weight). They are characterized by smooth, soft, moiré hair and a smooth feather. The area of the skin is 40-90 dm2, the thickness is uniform over the area and ranges from 1.3-2.5 mm. Characteristic of this type of hide is a thicker papillary layer than that of the skins of adult animals (from 20 to 30%), the thickness of the reticular layer is from 2/3 to 4/5 of the thickness of the dermis.

The papillary layer of the calf consists of thin bundles of fibers, the ligature of which is loosened by the hair bags, sebaceous and sweat glands located in it. The strength of the mold is determined by the well-developed mesh layer. The mold is used to produce chrome leather for shoe uppers. The best leathers are those made from milk milk (fed with milk); The skins of water-fed calves and grass-fed calves produce skins of poorer quality. Opoek produces valuable leather for high-quality clothing and footwear, as it has a smooth and defect-free grain;

The valuable properties of the drink include a small number of lifetime defects.

Outgrowth - the skins of calves that have fully mastered plant food, with transitional hair during molting. Characteristic of the skin of the outgrowth is that the thickness over the area is less uniform than that of the flange, and the presence of slight folds on the collar (milky stripes). Skin area 60--150 dm2, thickness 1.5--3.0 mm, weight up to 10 kg. The outgrowth is used to produce dense chrome leather for shoe uppers.

Cattle skins weighing over 10 kg, in turn, can be divided into light, medium, heavy raw materials - these groups are divided into non-contoured skins of cow, bull, and bull. Depending on age and gender, large cattle raw materials are distinguished:

Half-skin - skins of heifers and bulls with an area of 120 to 250 dm2, a thickness of 2.5-3.0 mm or more, weighing from 10 to 13 kg. The structure of the skin is close to the outgrowth, but has a noticeable shading. In addition, the skins of bulls have rough folds on the collar (frizz). Half leather is used to produce chrome leather for shoe uppers, shoe leather and industrial leather.

Goby - skins of gobies with an area of 200-270 dm2 and a thickness in the rump area of 3-4.5 mm, weighing from 13 to 17 kg. The skin is characterized by strong furrowiness and brownness. In the finished leather, folds on the collar stand out sharply, which prevents the production of chrome leather for the upper from this type of raw material. The bull is used for making yuft and insole leathers.

Bychina - skins of castrated bulls, differs in significant thickness (from 3.5 to 5 mm in the rump and 2.5 mm in the floors), area (300-570 dm2), and weight (light - 17-25 kg, heavy - over 25 kg). This type of raw material is used to produce high-quality sole, saddlery and technical leather, as well as rawhide. Skins of light weights are intended for making yuft.

Bugai - skins of uncastrated bulls with an area of 550-600 dm2, thickness from 4-4.5 mm to 6 mm in the collar area. The skin is less valuable than bull skin, as it has a very pronounced furiness.

Yalovka - cow skins. The weight of the skin in a paired state is from 13 kg and above. The skins of non-calving cows are denser, with a uniform thickness over the area, than cows that have calved many times, since they have stretched and weak floors (hollowness). Depending on the weight, the cowhide is used to produce leather for shoe uppers (light), yufti (light and medium), saddle leather (medium), sole leather (medium, heavy), technical leather (heavy).

Large raw materials, as a rule, produce less valuable and cheaper leather, since lifetime defects appear on the skin (as a result, grade decreases) and the unevenness of properties over the area increases (i.e. thickness, strength, chemical composition, microstructure, etc.) . Skins have lifetime defects and uneven topographic properties, but they are more preferable compared to heavy weight raw materials.

Raw materials of heavy weights are separated into separate groups, since their processing requires special and more labor-intensive technologies. Heavy skins include skins of mainly old animals with thickened skin tissue. Therefore, this raw material is often subjected to splitting - sawing in thickness into two or three layers. The top layer is called the face split, and the bottom layer is called the melon split. The face split is distinguished by the smoothness of the mesh surface formed from sawing with knives. Split leather is a loose material with uneven thickness and not very durable; velor leather is often made from it.

Bugay skins are distinguished by their high density, great thickness, the presence of rough thickened folds on the collar and uneven properties across the topography. Large skins are characterized by the presence of many defects. In addition, cattle skins of heavy weights are characterized by low strength indicators. This raw material, even if preserved and preserved in good quality, is prone to odor.

Buffalo skins in the collar part have clearly defined furrow folds. They are divided into light, medium and heavy raw materials, similar to cattle hides; almost half of them are subjected to splitting. Large raw materials from yaks and elk have the same weights as cattle skins. Deer skins (150-190 dm2) are used for the production of suede (clothing and footwear). Leather made from deer skins has high softness and sufficient strength.

Camel skins occupy a small share and produce leather of low quality (loose, low-strength), which is used for the production of haberdashery and clothing leathers. Skins are classified by weight: light - 10-17 kg, medium - 17-25 kg, heavy -* over 25 kg.

Horse skins have a thin epidermis (2--3% of the skin thickness). The thermostatic layer is more developed than that of cattle hides and contains a large number of sweat glands. Collagen bundles are thin, the ligature formed by them is loose.

The mesh layer of this type of leather raw material has a different structure depending on the area of the hide. A more dense structure is noted on the lower back, chest and some areas of the back; in other areas the interweaving of fibers is less dense. A distinctive feature of the chemical composition of skins is the presence of skin and subcutaneous fat, which has a low melting point.

Horse skins are divided depending on the weight and age of the animal. Small horse raw materials include foal skins:

Slime - skins of unborn or stillborn foals, unsuitable for fur production; skin area 30--60 dm2, weight 1--2 kg. The skins are thin and therefore used for the production of haberdashery leather.

Foal - the skins of suckling foals that have switched to plant food for foals weighing up to 5 kg, from which shoe and clothing leather is produced; with an area of 40-90 dm2 and more. It is a valuable fur raw material. Skins unsuitable for fur production are used for glove husky and chrome leathers.

Marking - young horse skins weighing 5-10 kg and area from 120 to 200 dm2. The thickness of the skin in the hazas is 2-2.5 mm, in the fronts - 1.5-2 mm. It is used for the production of chrome leather and yuft.

Horse meat is the skins of adult animals with an area of up to 400 dm2. The thickness of the skin in the haz area is 2-4 mm, in the front 1.5-3 mm. Horse meat, depending on its thickness, is used to produce chrome leather, yufti, sole and insole leather.

The quality of the resulting leather depends on the breed of animal - the skins of heavyweights have thicker and rougher skin tissue compared to the skins of trotters. Sometimes, when filming, the skins of adult horses are divided into front and haz, and each part of the skin is subsequently processed separately.

Horse hides are processed in rather small quantities - these are the skins of either sick or old animals. The quality of raw materials is generally somewhat worse than that of cattle hides. The properties of the slither-foal are similar to the slither-foal. Foal skins are the most valuable, as they are uniform in properties and have no defects.

The skins of donkeys, mules and hinnies are close in structure to the skins of horses.

Camel skins have a less dense structure compared to cattle skins due to the presence of fine downy hair in the thermostatic layer of the roots.

Goat skins are high-quality leather raw materials. They are used to produce leather for the uppers of fashion men's and women's shoes. The microstructure of the skin is characterized by a thin epidermis (2---3% of the thickness of the skin), approximately the same thickness of the papillary and reticular layers, a small amount of glands and fatty inclusions, as a result of which the papillary layer is less loose than that of sheepskin. The interweaving of collagen fibers is dense, the angle of the plexus is often horizontal, which gives the skin softness. Chrome leathers are produced from goat skins: chevro, goat, lining leather.

Pig skins as leather raw materials are used in significant quantities in Russia and in small quantities in other countries. More than 20 breeds of pigs are bred in our country, which is primarily due to the diversity of climatic and feeding conditions in individual areas. Pork skins have a unique structure. The outer layer of the hide is rough and rough, but has increased abrasion resistance, which is retained in the leather. Pork raw material contains a large amount of fat, so it is difficult to process and produces rather rough or rag-like, soft ruts for all purposes.

The epidermis, due to the weak development of hair, is thick (up to 5% of the thickness of the skin). Bristles, sebaceous and sweat glands and muscles that raise the hair are found throughout the thickness of the skin, especially in its lower layers. Due to the deep penetration of these structural elements into the skin, the dermis of pig skins is not divided into papillary and reticular layers.

The deep penetration of the bristles creates through holes in the dressed leather, making it water permeable. To eliminate this deficiency, special leather treatment is required. Loose leathers are often filled with prepolymers (acrylates, styrene) or powders (magnesium sulfate, talc, starch, etc.). Due to their low price, they are often used for the production of children's shoes and for clothing velor. Pig skins are used to make leather for shoe uppers and insole leathers.

The leather industry uses sheep skins that are unsuitable for making sheepskin and fur products. A feature of sheep skins is the thin epidermis (1.8-1.5% of the thickness of the dermis). The dermis is clearly divided into papillary (thermostatic) and reticular layers, and the thickness of the papillary layer is usually greater than the thickness of the reticular layer (from 50 to 80% of the thickness of the dermis). The papillary layer is loose due to the presence of a large number of hair bags, sebaceous and sweat glands, as well as muscles that lift the hair. The dermis contains a significant amount of fat, which weakens the collagen ligature. These structural features of the hide give leather made from sheepskin low strength, greater ductility, friability, and water permeability. They produce chrome leather (chevrette), haberdashery, clothing and lining leather from sheepskin.

Cattle skins must be removed in a layer with a longitudinal cut along the white line (the anatomical border of the fusion of the abdominal muscles in animals) from the head or without the head part of the skin, preserving the skin from the legs. The front legs should be skinned to the middle of the fetlock joint, and the hind legs should be skinned to the middle of the hock joint.

The skin from the head of cattle must be removed in two parts - the cheeks together with the forehead at one of them, and from the tail at a distance of no more than 8 cm from its base.

The isthmuses connecting the head part with the main part, depending on the weight group, should have the width indicated in 5.

The area, weight and thickness of cattle hides vary within wide limits. The weight of the skin is on average 7-8% of the animal's weight.

The area of the mold-slime is on average 40-60 dm2. Thickness in the croup area is 1.4-1.5 mm, in the collar 1.7-1.9 mm, in the floors 1.2-1.5 mm. Its skin is distinguished by a loose knitting of bundles of collagen fibers and a relatively large thickness of the epidermis (3-4% of the thickness of the skin). The area of the mold is 40-90 dm2, the average weight is about 3.5 kg. The mold is characterized by its great uniformity in thickness (from 1.3 to 2.5 mm). The thickness of the epidermis of the skin is 2% of the total area of the skin, and the papillary layer is 30-35%. The absolute thickness of the papillary layer is approximately the same as that of the mucosa, but its relative thickness is different - it decreases to V3 of the thickness of the entire dermis. The bundles of collagen fibers of the papillary layer are somewhat thicker than those of the mucosa. The reticular layer of the dermis has a significantly greater (both absolute and relative) thickness and a denser and more complex 30 (loop) connection of collagen fiber bundles. Opoek has a thin and beautiful gauge and is characterized by uniform thickness and high strength, combined with softness and elasticity, which makes it a valuable raw material for the production of chrome leather for shoe uppers.

The area of the outgrowth is from 60 to 150 dm2. The thickness in the saddle area is 3-4 mm. Individual sections of the skin differ in thickness much more than that of the calf. Based on the ratio of the papillary and reticular layers of the dermis, the density and complexity of the interweaving of the fibers of the dermis, the outgrowth approaches the skins of adult animals. The offspring begins to show signs of sexual differences. On the neck part of the skin removed from a bull, there is usually a clearly visible wartiness - rough folds.

Compared to the fluff, the outgrowth has a more strongly developed stratum corneum of the epidermis; it is characterized by overgrown, coarse, dull, often slightly shaggy hair, almost without fluff. The grain of leathers produced from the outgrowth is much rougher and not as smooth as that of leathers from the calf. The outgrowth is usually used to produce chrome leather for shoe uppers.

The area of half-leather skins ranges from 120 to 250 dm2. The thickness in the paired state in the saddle area is usually 3-3.5 mm. The brownness of the skins of the half-derm is more pronounced than that of the skins of the outgrowth. Half-leather skins taken from bull calves have a pronounced, furry appearance. The histological structure of the skins of the demi-derm is close to the structure of the skins of adult animals, however, the density of the ligature of the mesh layer in it is somewhat less, the bundles of collagen fibers are slightly thinner, and somewhat smoother. Half-leather skins are used to produce chrome leathers for shoe uppers and yuftas, as well as for leather for technical purposes.

The area of bull skins is from 200 to 300 dm2. Thickness in the croup area is 3.5-4.5 mm, on the collar - 2.5-3.5, on the floors - 2-3 mm. It is characterized by strong borustiness, spreading over a significant part of the skin. The microstructure of the skin of bulls is close to the microstructure of the skins of adult animals. The skins of bulls are used to produce insoles and leather goods.

The area of the trap is usually 200-400 dm2. The thickness of the cow, light in the rump, is 3-3.5 mm, in the collar - 2-2.5, in the floors - 1.5-2.5 mm. The heavy cowhide has a thickness of 3.5-4.5; 2.5-3.5 and 1.5-3.0 mm. Cowfish are characterized by great runawayness. Hollowness is often observed, especially in the skins of cows that have calved many times, that is, it is characterized by greater thinness, looseness and increased width of the floor than the floors of normal skin. Light, medium and heavy cowhide is used mainly for the production of leather for shoe uppers, and thinner skins are used for chrome-tanned leather. The cowhide is doubled, which makes it possible to obtain a split leather suitable for use as leather for shoe uppers (velor), lining and mitten leathers. Dense harvest of heavy weights is also the raw material for the production of rawhide, saddle leather and light sole leather.

The area of the bullock ranges from 250 to 550 dm2. For bulls of large size and weight, the thickness of the saddle cloth is usually 4.5-5 mm, the collar is 3.5-4.5, and the pop is 3-4 mm. The thickness of light beef on a saddle cloth is 2.5-3.5 mm, on a collar - 2-3, on floors - 2-2.5 mm. The pattern of changes in the thickness of the bullock over its area is almost the same as that of the cowfish, but hollowness is not characteristic of it. Borushiness is absent or slightly expressed. The knitting of the bundles of collagen fibers in the dermis is somewhat denser than that of cowhide, and the bundles themselves are slightly thicker. Light bull meat is used mainly for the manufacture of elements of the bottom of shoes. Heavy bull meat produces valuable technical and saddle leather, as well as raw meat. Currently, bull meat is used to produce leather for shoe uppers.

The area of bug skins reaches 500 dm2, and the thickness in the saddle part is 4.5-5.5 mm. The thickest skin of the bull is in the head part (up to 8-9 mm). The thickness of the floor and the edges of the saddle cloth are almost the same. Borusiness is highly developed. Bugay skins are, as a rule, used for the production of plantar and industrial leathers.