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Cosmetic clay, its types and uses

Typically, the chemical composition of low-melting clays is, %: SiO 2 – 60...85; Al 2 O 3 together with TiO 2 – no less than 7; Fe 2 O 3 together with FeO- no more than 14; CaO + MgO – no more than 20; R 2 O (K 2 O + Na 2 O) – no more than 7.

Comparative characteristics of the chemical composition of various clays are given in table. 1.

Table 1

Chemical composition of clays

Silica(SiO 2) is found in clays in bound and free states. The first is part of clay-forming minerals, and the second is represented by siliceous impurities. With an increase in SiO 2 content, the plasticity of clays decreases, porosity increases, and the strength of fired products decreases. The maximum content of SiO 2 is no more than 85%, including free quartz – no more than 60%.

Alumina(Al 2 O 3) is found in clay-forming minerals and mica impurities. With increasing Al 2 O 3 content, the plasticity and fire resistance of clays increases. Usually, the alumina content indirectly judges the relative size of the clay fraction in the clay rock. Alumina is contained from 10-15% in brick and up to 32-35% in refractory clays.

(CaO and MgO) participate in small quantities in the composition of some clay minerals. At high temperatures, CaO reacts with Al 2 O 3 and SiO 2 and, forming eutectic melts in the form of aluminum-calcium-silicate glasses, sharply lower the melting point of clays.

Alkaline earth metal oxides(Na 2 O and K 2 O) are components of some clay-forming minerals, but in most cases they are involved in impurities in the form of soluble salts and in feldspathic sands. They lower the melting point of clay and weaken the coloring effect of Fe 2 O 3 and TiO 2. Alkali metal oxides are strong fluxes and contribute to increased shrinkage, compaction of the shard and increase its strength.

The limit value of sulfur compounds in terms of SO 3 is taken to be no more than 2%, including sulfide - no more than 0.8%. In the presence of SO 3 more than 0.5%, including sulfide no more than 0.3%, in the process of testing clay rock, methods for eliminating efflorescence and efflorescence on unfired products should be determined by converting soluble salts to insoluble ones.

2.3. Granulometric composition of clays.

The granulometric composition of clays is the distribution of grains in a clay rock according to their size. Typically, the grain composition of various clays is characterized by the data given in Table 2.

Humanity has long been familiar with the healing properties of clay. Even in ancient times, it was used not only for making dishes, but also for medicinal purposes. The Egyptians used this product for embalming, and ancient scientists and doctors, describing the clay, spoke of its healing power. The famous Russian doctor Botkin successfully used it to treat diseases of the heart and blood vessels, Graves' disease, and disorders of the nervous system. Today, clay is widely used in both official and alternative medicine; it is used to eliminate cosmetic problems. As you can see, the uses of clay are extensive, and therefore let’s talk in more detail about what clay is, its medicinal properties and uses, and about the use of clay by humans for health purposes.

What exactly is clay? It is a sedimentary fine-grained rock, plastic when moistened and dusty when dry. Clay consists of the minerals montmorillonite, kaolinite or other layered aluminosilicates. Its mineral composition is so diverse that it is comparable almost to fruits or vegetables. It is able to absorb carcinogens and toxins, thereby cleansing the body. The clay is high in silicon and aluminum, contains calcium, magnesium, iron oxide and other oxides, and also contains titanium anhydride.

It is often used to treat atherosclerosis, tuberculosis and even multiple sclerosis, precisely due to its high silicon content.

Clay is divided into different types depending on its color, which is determined by the increased presence of salts and other components in it. This determines the range of its use.

Blue clay is high in cobalt and cadmium. It is most often used for medical purposes.

Red contains potassium and iron. Thanks to these substances, it has a good effect on joints, muscles and spine. Mainly used for appliques.

Green contains a lot of divalent iron and copper. It is suitable for the treatment of tumors, liver, pancreas. It is used to treat oily skin and hair.

Black and dark brown contain a lot of iron and carbon. It is used in the cosmetics industry.

In yellow - sulfur, sodium, ferric iron. It is used to make compresses and applications for sore joints. It also treats skin rashes and cellulite.

The properties of clay depend on the size of its particles. They have enormous adsorption capacities, with a surface area of ​​about 80 square meters per gram. The sizes of the particles and their properties are directly related to the origin of the clay.

High adsorption allows clay to absorb toxins, putrefactive elements, and harmful acids. It is used to treat tumors, both benign and malignant.

There is a theory that by using clay you can positively influence the human biofield.

Blue clay is mainly used for treatment.

Its external use occurs for radiculitis, arthritis, diseases of muscles and tendons, skin ailments, menstrual irregularities, prostatitis and colds.

Moreover, it can be used both for chronic ailments and for acute forms of disease.

Clay is used for lotions, wraps, and rubbing. Place it on the sore spot with a tile one and a half to two centimeters thick. However, it can be cold, warm or slightly warmed, depending on the disease.

For example, warm clay is used for diseases of the kidneys, liver and joints. And if abscesses are being treated, it is recommended to apply compresses of clay water and replace them regularly.

Clay can also be used for douching for various diseases of the female genitourinary system. At the same time, take 3-4 tablespoons per liter of water. In this case, the water should be heated to body temperature.

When treated with clay, quite serious deterioration of the condition can be observed. But often they do not require cessation of therapy, but merely indicate the release of toxins from the body.

Clay treatment is best carried out in combination with dietary nutrition, massages, douches, sunbathing, aromatherapy and foot reflexology.

There are methods for internal use of clay. To do this, it is best to take it in a whole piece, fatty, without foreign impurities. By taking it internally, atherosclerosis, ailments of the digestive system, kidneys, liver, gallbladder, blood and skin are treated.

Clay balls are an excellent remedy against oral diseases and tooth pain. They should just be sucked and rolled in your mouth.

Clay is great for purifying water. To do this, take one piece per liter of water. After this, the container with water should be set aside and allowed to stand for a couple of hours. Rest assured - clay absorbs all toxins and toxic substances.

Clay is also widely used in the cosmetics industry. It is used to care for the entire body, preparing cleansing and rejuvenating masks.

You can make this mask yourself by mixing it to a paste with cucumber juice and water. Apply the resulting mixture to your face and leave until completely dry.

Rinse off with warm water. This mask will have a cleansing, nourishing and tightening effect. But you shouldn’t do it more often than once a week.

In conclusion, let me remind you about the use of clay for storing vegetable harvests. Many gardeners, before storing carrots and potatoes, dip the fruits in a clay mash. Then, after drying, a protective film is created around the vegetable. Practice shows that crops processed in this way are stored longer.

As you can see, using clay has a lot of options and possibilities. Its medicinal properties make it possible to treat, because it has practically no contraindications, and therefore is successfully used in various branches of medical science, it preserves the harvest, and it can also take care of the beauty of your skin. Conclusion - clay has many faces and is certainly useful!

The art of making vessels and other household items from clay can be considered the most ancient, becoming one of the first types of technical production. What could be more ordinary than clay! Meanwhile, its role in people’s lives is great and is associated with its unusual properties. The observant mind of man drew attention to them in ancient times. Clay fired in a fire is the first artificial material produced by man. The properties of this material were gradually revealed to man. Until now, a third of humanity lives in mud huts. And this is not counting the houses made of baked bricks. Not only walls are made from clay, but also hearths and roofs. To increase the strength of such an adobe floor, it is watered with salt water from time to time. Cuneiform writing, which first appeared in Mesopotamia, was pressed onto thin clay tablets. And the complex composition of modern paper necessarily includes white clay.

Clay has been used since ancient times as a remedy. Sprained hilus was treated with a plaster of yellow clay diluted in vinegar. And for pain in the lower back and joints, clay diluted with hot water with the addition of kerosene was applied to the sore spots. Healers preferred to use oven clay when performing divination. She was treated for the evil eye and fever. Small clay pots (makhotkas) were placed on the body for colds as medical jars. They even did “brick inhalations” by heating a brick, pouring onion skins on top of it, and inhaling the smoke. And by sprinkling such a brick with wormwood or juniper, they scared away flies and mosquitoes.

They even ate clay. Residents of the North still eat “earth fat” - white clay. They eat it with reindeer milk or add it to meat broth. And in Europe they made delicacies like candies from clay. There is an old Russian riddle: “I was on a kopanets, I was on a topavda, I was on a circle, I was on a fire, I was on a scald. When he was young. then he fed people, and the old flock began to swaddle.” Until recently, any villager would have quickly figured it out. This is an ordinary stove pot. And the riddle itself tells in detail his “life path”. “Kopantsy” in Russian villages was the name given to the pits where clay was mined. The potters respectfully spoke of her: “alive.” “Living raft” found in nature is so diverse in composition that you can find a ready-made mixture for making any type of ceramics.
Naturally, if deposits of valuable types of clay are found, then pottery production quickly grows around them. This, for example, happened in Gzhel near Moscow, where white clay was found.

Clay, unlike sand, which filters moisture, absorbs it completely, without allowing it to pass deeper. When mixed with water, clay becomes a plastic “dough” that can be molded into any shape. Having dried, it retains the shape given to the “dough” and after firing it becomes hard as stone. Clay is a product of rock destruction. The process of clay formation occurs constantly, but there was a time when clay formation took place on a gigantic scale. This phenomenon dates back to time immemorial, to the glacial and diluvial periods, when the mechanical part of the work of rock destruction was carried out by glaciers moving into the plain. Any clay contains alumina, i.e. aluminum oxide, and silica, and minor impurities can be various alkalis, lime, magnesia, iron oxides and titanic acid.

There are clays consisting predominantly of one mineral (for example, kaolinite refractory clays - kaolins), but much more often they are polymineral, being a mixture of the minerals kaolinite, halloysite and montmorillonite. The rocks that preceded the clays consisted mainly of feldspars and micas. Spars are found in all three types of rocks on Earth - igneous, metamorphic and sedimentary. Solidified magmas - granites, pegmatites - are the ancestors of the clay mineral kaolinite. Halloysite was usually preceded by diabase and gabbro; montmorillonite is a product of the decomposition of volcanic ash, tuff and lava. Over the course of thousands of years, the parent rocks of the clays have been destroyed, decomposed, weathered, turning into fragments, screes and, finally, into tiny particles. Sometimes they remained at the place of their formation.

This is how “primary” and “residual” clay deposits appeared, usually thick (up to a hundred meters or more), occupying significant areas. They mainly consist of kaolin (“Kaolin” is a corruption of the Chinese words “gao ling”, i.e. “high hill”; this is the name of the village in China where these clays were first mined). These clays, which form a light-colored shard when fired, are used to make fine ceramics - porcelain and earthenware. But more often, rivers, winds, and moving glaciers transport clay materials over long distances. Gradually they settle in stagnant waters. The settled silt layers are homogeneous in their structure. On the way, they are subjected to natural “extraction”, enrichment, and liberation from undecomposed rocks and impurities. Such deposits (the majority of them) are layered, their thickness is relatively small, and their occurrence area varies.

These ubiquitous, shallow Quaternary clays are commonly used to make pottery and building bricks. ??Sometimes clay particles manage to avoid encounters with water flows containing substances that usually pollute clay. In this case, deposits of pure, highly refractory, low-iron clays are formed. They are used for ceramic products with special properties, used in special industries. Climatic zonation has been revealed in both ancient and modern deposits of clay minerals. In the icy Arctic zone, minerals such as hydromica and chlorite predominate; in the moderately humid, cold zone - montmorillonite; in the tropical zone - kaolinite. Scientists have discovered another amazing property of baked clay. It was discovered that during the firing of clay products they become magnetized, recording the features of the Earth's geomagnetic field at that moment in time. Knowing the geomagnetic field of our planet in ancient times, the age of ceramics can be determined with an accuracy of twenty-five years. Archaeologists are helped in this by petrography, microscopy, spectral analysis, and x-rays.

Pliny the Elder in the 1st century. n. e. in his “Natural History” he distinguished white clay (argilla) from ordinary, ordinary clay (lutum) and from just soil (terra). In ancient Greek, the word "keramos" originally meant clay; it is mentioned by Homer in the Iliad (8th century BC). In the Old Slavic language there was no word “clay”, but there was a word “Brnie”, meaning clay mixed with water, which is probably where the name of the Czech city Brno comes from. The concept of "potter" in ancient Slavic was denoted by the word "zdun", the root "zd" still forms such words as creator, create, building. The word “clay” has a later origin, probably from the word “clay” - alumina (aluminum oxide), which is part of any clay. Clay on our planet appeared a long time ago, during the interglacial period, which was accompanied for many millennia by the melting of the ice cover, which was up to 2 km thick in Europe. The melting caused powerful water flows, which did the work of clay. They elutriated, moved and redeposited clay and sand, which led to their mixing. These processes are associated with the formation of numerous clay deposits in Europe, particularly in Russia, with different properties, which is not observed on other continents.

If we approach clay from a scientific point of view, then it is a dispersed, that is, consisting of solid particles of different sizes, sedimentary rock of lamellar minerals, chemically hydroaluminosilicates, and accompanying impurities of other minerals. Well, it’s clear what “hydro” is, “aluminum” probably too, and silicates are compounds of silicon with oxygen. Lamellar minerals, when interacting with water, make the clay plastic, capable of molding and maintaining its given shape when dried. Trace minerals such as quartz (sand), carbonates (chalk, marble, limestone, dolomite, magnesite) and feldspar (the most common feldspathic rocks are granites) are non-plastic, and their presence “thins” the clay, reducing its plasticity. There are a number of classifications of clays according to their chemical and mineralogical composition, origin, and application, but none of them covers the entire set of characteristics useful in determining the suitability of clay raw materials for a particular production.

Division of clays accepted in geology:
a) transported by water, glacier, wind (secondary deposited);
b) formations remaining in place (primary clays);
c) metamorphosed rock-like rocks.
In the classification scheme according to GOST 9169-59, clay raw materials are divided into four groups: kaolins, clays, crackers (refractory stone-like clays) and shale clays (poorly soaked in water). These groups are divided into subgroups:
a) by the content of aluminum oxide in the calcined state (more than 40% - highly basic, from 40 to 30% - basic, from 30 to 15% - semi-acid, less than 15% - acidic);
b) by fire resistance (fireproof - melting at temperatures from 1580°C and above; refractory - melting from 1580 to 1350°C, and low-melting - melting below 1350°C);
c) according to the degree of cohesion or plasticity (forming moldable dough with the addition of normal sand: more than 50% are binders, from 50 to 20% are plastic, less than 20% are lean; do not form dough at all).

Along with those considered, there is an industrial classification of clays, based on their assessment based on a combination of certain characteristics, such as color and appearance after firing, sintering-melting interval, strength of the product upon impact, resistance to sudden changes in temperature. These characteristics determine the industrial purpose and name of the clays. Already in the Middle Ages, names of clays such as brick, pipe, tile, pottery, earthenware, white-burning, clinker and others were developed and still exist. At that time, clays, by the way, were assessed only by touch, and their properties could be assessed by medieval masters. And now, I think, it is not a sin to return to such an assessment of clay, since direct contact with the material at the very beginning of the work unites the master and the clay into one whole, allows them to feel each other, for if the tool is an extension of the potter’s hands, then the product is an extension of his soul. So, the clay used in pottery must be heavy, oily, elastic, in general, with a solid character - it must keep its shape. The color of clay can be red, brown, blue, green, gray or white. Sometimes clays of chocolate color (so-called snickers) or dirty black are found. But I don’t recommend dealing with them, because when fired, organic impurities, a large amount of which gives them a dark color, give off such a spirit that you can take away the saints. The color of clay comes from aluminum oxide, iron oxide and titanium oxide. If the total amount of iron and titanium oxides does not exceed 1 percent, then the clay is white even after firing, but if there are more than 1 percent, then the clay after firing is red, despite the fact that in its raw form it is green or blue.

Quartz (sand) is usually present in clay deposits in the form of rounded, colorless or colored grains. Its amount in clays can vary - from several percent to several tens of percent. The sand that is added to pottery clays to thin them must be ground (otherwise the clay will rub your hands like sandpaper), and its amount should not exceed 25 percent (optimally 15%). As ground sand is added (up to 15%), the plasticity of pottery clay increases; further addition of sand reduces the plasticity. The amount of sand in clay also affects the shrinkage of the product during firing. Therefore, if you want to reduce the shrinkage of clay during drying, which in turn will reduce unnecessary deformation of products and save you from insidious cracks at the bottom of large-diameter vessels, then add up to 25 percent sand or ground fired shards to the clay. In Ancient Greece, for example, grus was added to clay, which was nothing more than crushed granite. Very often, especially in low-quality clays, there are impurities of calcium and magnesium carbonates (chalk and dolomite) in the form of large and small grains. They are useful and harmful at the same time. I will say a few words about the dual role of these impurities during the firing of ceramics. In a finely dispersed state, these impurities are strong fluxes (additives that reduce the sintering temperature), but at the same time, at firing temperatures up to 1000°C, they reduce the strength of the ceramics, and at higher temperatures, deformation of the products is observed. The chalk content in pottery clay can reach 25 percent, but it requires even distribution and very fine grinding. If carbonates are present in the clay in the form of large inclusions, then the oxides of calcium and magnesium remaining after firing begin to absorb moisture from the air, form hydroxides, increase in volume and ultimately can rupture the product. These harmful inclusions are called "dutik".

Quite common impurities in clay are gypsum and pyrite. They are noticeable after firing in the form of small black “flies”. Pyrite in clay is crystals with a metallic yellowish sheen; gypsum sometimes forms clusters of large crystals visible to the eye. They can only be removed manually. Harmful impurities in clays are also soluble salts - sulfates and chlorides, which form so-called efflorescences on products. Soluble salts appear in the form of a salt coating on the surface of fired clay products. To combat “efflorescence,” it is recommended to add barium carbonate to the clay composition. In a small pottery workshop, it is better to combat this problem with the correct firing regime. "Efflorescence" is formed mainly at temperatures of 400-500°C, so it is recommended to quickly raise the temperature to 600°C. In some cases, the presence of carbonaceous materials in clay and recovery firing in the range of 700-800°C will be suitable for the decomposition of “efflorescences”.

Organic impurities, as a rule, burn out during firing and leave almost no traces on the surface of the products, except for small shells formed during the combustion of wood particles. (But this property is used when decorating products. For example, inclusions of grains of rice, wheat or even peas in the surface of products after firing will leave a characteristic mark.) A large amount of organic carbon in clay can create a local reducing environment during firing, which promotes earlier sintering clay and with a thick layer (brick, for example) can give the shard local deformation and undesirable coloring. The composition and pottery qualities of the clay are finally determined only after the production and firing of a test product. The easiest way is to purchase clay at a specialized factory or directly in a quarry of some deposit. At factories it is sold in two types: quarry - brought directly from the mining site, which means it requires appropriate processing, or in powder. The powder is a mixture ready for use. All that remains is to cover it with water. Powder, of course, is more expensive, but by purchasing it, you will save time on cleaning the clay. The clay powder purchased from factories producing ceramic tiles and bricks contains 10-12 percent ground glass, which will give strength to future products. But the pottery properties of clay made from such powder are somewhat reduced due to the presence of the same glass.

Currently, organizations selling ready-made pottery clay have appeared in large cities. There you can buy clay of any composition, small and large fireclay, gypsum, ready-made glaze and other materials necessary for a potter. But if this is not possible, then the necessary clay can, in principle, be found anywhere, for example, on a steep hillside. Clay can even be found on the side of roads or, best of all, along the banks of swamps or small bodies of water, which are formed because rain or spring water falls into a clay bowl. The required clay (usually blue or green) lies either immediately under the turf, or at a depth in a layer of varying thickness. This clay, like quarry clay, requires careful preparation. It needs to be dried, first broken into small pieces. Sufficient time must be spent on this drying. When the clay is completely dry, fill it with water, preferably hot. So much water is needed so that only isolated islands of clay remain on its surface. After swelling, the mass should be laid out on a table covered with canvas or any other rough cloth. Wait until the clay is freed from excess water and acquires the moisture necessary for work. When drying the clay, it must be periodically turned over and, preferably, kneaded.

The main quality of pottery clay is that it must be clean, that is, not have any inclusions. Of course, some result can be achieved using any clay, but it is unlikely that the products will be of high quality. For a good craftsman, a small pebble or even a large grain of sand can be commensurate with the thickness of the vessel wall and interfere with his work. You can clean pottery clay by hand (which is unproductive, but quite possible at home) or by pressing it in a plastic state through a fine mesh, as if imitating an industrial filter press. You can also soak the clay in a barrel for purification, that is, dilute it to a slip (the state of liquid sour cream) and wait for large, heavy inclusions to settle to the bottom. After which the pure fraction is drained, making a hole in the barrel at the level of the beginning of the pure slip, and dried to the desired state.

Now we need to talk a little more about the relationship between clay and water. Despite the fact that their characters are similar, it is very easy to quarrel between them, and then you won’t expect anything good. If you overdo it and add too much water when mixing the clay, it will be difficult to remove. The clay dough will be uneven, with lumps. Clay, being a hygroscopic substance, adsorbs moisture from the air, is wetted by water and is capable of swelling in a state of strong watering. Moisture adsorbed by clay is called tightly bound water, in contrast to loosely bound water, which is more freely located between clay particles, more mobile and squeezed out of the clay during compression. Strongly bound water makes up 0.8-1.0 percent of the moisture content of kaolin, freezes at temperatures well below zero, and almost does not conduct electric current. Strongly bound water naturally turns into loosely bound water, which becomes more abundant the closer the state of the clay approaches the working water content, that is, to the state of clay and water when the clay mass exhibits the optimum of its plasticity and its ability to be molded. With the correct moisture content, the clay mass does not stick to the back of the hand. This working water content varies for different clays; for example, in loess it is 18-20 percent, in kaolin - 28-31 percent, in spondylic clay - 31-33 percent, in Chas-Yarskaya - 30-32 percent, in Troshkovskaya - 30-36 percent. With a further increase in water content, the clay loses its ability to maintain its shape and begins to flow like a viscous liquid.

This information about the properties of clay is quite enough to start working with it. In general, we can talk about the properties of clay for a very long time; there are more than thirty names of clays alone, and each of them has a dozen combinations with various additives. When the clay is freed from excess water and acquires the moisture necessary for work, that is, it will knead with effort in your hands, it must be kneaded properly and placed in a plastic bag, and the bag in a barrel with a tight lid, where it should lie for a while before starting work. less than a day, or better - several days. However, clay can remain in a barrel for a long time - all the time until you use it up. To mince clay, many craftsmen adapt various mechanisms, such as industrial meat grinders. Similar “mechanization” can be used at other stages of clay preparation. And another very important point. Just before you start working with clay, you need to knead it thoroughly again, tearing the lump of clay into two parts and forcefully connecting them back. In this way you can free yourself from most of the air - the last and most insidious enemy of the potter. Firstly, when pulling a vessel on a pottery wheel, your hands will fall into air pockets, and you can tear the product or tear it off the wheel. And secondly, the air pockets remaining in the clay can rupture the product during firing, since air, as is known, expands when heated. In industrial production, air is removed using a vacuum press.

Clay is a mineral and is a sedimentary, fine-grained rock. When dry it is dusty, but when moistened it becomes plastic and can increase in size.

Description

The material contains one or more minerals of the kaolinite group. The base may be a mineral of the montmorillonite group and other layered aluminosilicates, which are also called clay minerals. May contain carbonate and sand particles.

The rock-forming mineral is kaolinite, which consists of silicon oxide in a volume of 47%, aluminum oxide - 39%, and water - 14%. A significant part of the chemical composition of yellow clay is Al 2 O 3 and SiO 2. The material can have the following colors:

  • green;
  • blue;
  • brown;
  • black;
  • lilac.

The color is due to ion impurities, which are chromophores.

Main types

Clay is a mineral that has several types. Each of them has its own area of ​​use. If the plasticity number reaches 0.27, then the material is called light. When this parameter exceeds the mentioned figure, the clay is heavy. Typically, the clay mined and sold largely consists of kaolin, which is used in the pulp and paper industry and in the production of refractory products, as well as porcelain.

Clay is a mineral, which is also represented by a construction variety, as well as clay shale. This material is used to make refractory bricks and also forms the basis of heat-resistant products. Among the species, bentonite occupies an important place. It is formed by the chemical breakdown of volcanic ash. In water, this variety swells and increases in volume several times. Used in drilling wells and in the production of drilling fluids.

Clay is a mineral, which is also represented by the fulling variety, which is valued for its bleaching properties when refining petroleum products. Filters are made from this type of clay, which are used in the purification of mineral and vegetable oils.

Another variety is lump clay, which is called pottery clay. It has found its application in the manufacture of dishes. Shale is an important raw material that, along with limestone, is used in the production of Portland cement. The most common in nature are:

  • sandstone clay;
  • white clay, which is kaolin;
  • red clay.

The varieties are used for the production of refractory products, as well as earthenware and porcelain.

Basic properties

Clay is a mineral that has a number of properties, among them the following should be highlighted:

  • air and fire shrinkage;
  • plastic;
  • sinterability;
  • fire resistance;
  • viscosity;
  • color of ceramic shard;
  • porosity;
  • shrinkage;
  • dispersion;
  • swelling.

Clay is the most stable waterproofing material that does not allow moisture to pass through, which is one of the important qualities. Clay soil has stability. It is developed in wastelands and wastelands. The development of root vegetation in clay deposits is impossible.

To preserve the quality of groundwater, the material's water-impermeability is useful. Most of the high-quality artesian springs lie between the clay layers.

Technical characteristics and additional properties

Now you know whether clay is a mineral. However, this is not all there is to know about this rock. It is also important to become familiar with the basic characteristics, for example, the specific and volumetric gravity of ground clay, which is 1400 kg/m3. Fireclay clay has a characteristic value of 1800 kg/m3.

When the clay is in the form of a dry powder, its volumetric and specific gravity is 900 kg/m3. The density of wet clay is also important, which varies from 1600 to 1820 kg/m3. For dry, this figure is approximately 100 kg/m3. Dry raw materials have thermal conductivity that reaches 0.3 W/(m*K). For the material in a wet state, this parameter is 3.0 W/(m*K).

Symbol

The symbol for clay should be of interest to you if you are studying it. When a material contains sand impurities, it is indicated by strokes and dots. If there are boulders in the clay, then circles are added to the strokes. Shales have the same designation as laminated clay; they are long streaks, densely spaced and drawn in the direction of the strata.

Sand and clay

Sand and clay are the minerals that are most common. They are formed during the destruction of rocks such as granite. Under the influence of water, sun and wind, granite is destroyed, this contributes to the formation of clay and sand. They differ in color from each other: sand is often yellow, sometimes gray, while clay is white or brown.

Sand consists of individual particles of different sizes. The grains are not attached to each other. Therefore, sand is free-flowing. Clay consists of small particles, similar to scales, well bonded to each other. Sand is a sedimentary rock or may be a man-made material made from rock grains. It usually consists of almost pure quartz mineral, the substance being silicon dioxide.

The natural material has grains with sizes within 5 mm in diameter. The minimum value is 0.16 mm. Sand can be classified according to accumulation conditions. Taking this into account, the material is divided into the following types:

  • alluvial;
  • deluvial;
  • nautical;
  • lake;
  • aeolian.

If sand appeared as a result of the activity of reservoirs, then it has a more rounded particle shape.

Properties of granite

Sand, clay, granite, limestone are minerals. If we look at granite in more detail, it is an igneous platonic rock of acidic composition. It is based on:

  • potassium feldspar;
  • plagioclase;
  • quartz;
  • biotite;
  • muscovite

Granite is common in the continental crust. Its density reaches 2600 kg/m³, while the compressive strength is 300 MPa. The material begins to melt at 1215 °C. In the presence of pressure and water, the melting point decreases to 650 °C.

Granite is the most important rock of the earth's crust, it is widespread and makes up the majority of all components. Among the varieties of granites, alaskite and plagiogranite can be distinguished. The latter has a light gray color with a sharp predominance of plagioclase. Alaskite is a pink granite, it contains a sharp predominance of potassium-sodium feldspar.

Properties of limestone

Looking at the table of minerals: sand, clay, granite, limestone, you can focus on the latter. It is a sedimentary rock of organic or chemogenic origin. The basis is most often calcium carbonate in the form of crystals of different sizes.

Limestone is made up of marine animal shells and debris. The density of the material is 2.6 g/cm 3, its frost resistance is F150. The compressive strength is equivalent to 35 MPa, while the loss of strength in moisture-saturated conditions reaches 14%. The porosity of the material is 25%.

Finally

Clay is a sedimentary rock that, when combined with water, begins to soak and separate into individual particles. As a result, a suspension or plastic mass is formed. Clay dough is plastic, and when raw it can take any shape. After drying, the material retains it, but decreases in volume. Plastic clays are also called fatty clays, because they feel exactly like that to the touch. If the plasticity is low, then the material is called lean. Bricks made from it quickly crumble and have poor strength.

The rock is sticky and has a binding ability. It is saturated with a certain volume of water, and then no longer allows liquid to pass through, which indicates water resistance. Clay has a covering ability, so in the past it was widely used for whitewashing the walls of houses and stoves. Among the properties, sorption capacity should be highlighted. This is expressed in the ability to absorb substances dissolved in water. This characteristic allows the clay to be used for purifying vegetable fats and petroleum products.

The remarkable properties of natural mineral clays have been known since ancient times. Even then, clay was actively used not only in medicine, but also in cosmetology. Ancient healers made various poultices and rubs from it. Clay was taken internally when its absorbent effect was needed. It helped get rid of bacteria well and allowed toxins to be removed from the body. Clay therapy helped with various poisonings, epidemics and muscle pain. Now clay is no less popular. It is often used in dermatology. Medicinal ointments and pastes are made from it. Clay is also widely used in cosmetology. It is usually included in face masks.

The main property of cosmetic clay is cleansing and drying the skin. Clay is able to absorb excess sebum and sweat gland secretions. In addition, it perfectly cleanses the facial skin, eliminates peeling, irritation and redness. Clay masks in facial care can be used for both oily and dry skin. In addition, clay can enhance the bactericidal effect of certain substances. It is often added to anti-inflammatory ointments and masks. There are different types of cosmetic clays, which we will look at in this article.

Clays differ in color, which depends on their mineral composition. The composition of clays depends on their place of origin. Clay can be white, blue, green, red, yellow and black (gray). Each type of clay has its own specific qualities and is used in medicine and cosmetology for different purposes. You can buy natural cosmetic clay in pharmacies or cosmetics stores.

White cosmetic clay White clay (Kaolin) It appears as a homogeneous white powder with a yellow or grayish tint or may be a dense lump. It feels greasy to the touch. It dries, cleanses and tightens the skin well. White clay is able to absorb excess oil, it significantly tightens pores. You need to know that this type of cosmetic clay also has a slight whitening effect. In addition, with its help, a woman can even out the oval of her face. White clay is also an excellent antiseptic. It is used as part of bactericidal and anti-inflammatory facial care products. Regular use of white clay will make your skin velvety and more elastic. Your complexion will improve and become fresher. White clay is the most common. It is on this basis that most face masks are made. It is hypoallergenic and suitable for all skin types, even the most sensitive, and for oily skin it normalizes the fat balance. Kaolin is the most delicate abrasive, which allows it to be used as a soft scrub. This property of white clay is very valuable for skin with inflammatory acne, for which rough abrasives are unacceptable, as they can aggravate the course of this skin lesion. It is also used in the form of powders, ointments, pastes, as well as for diaper rash and burns. White clay is an indispensable component in cleansing masks. In addition, homemade tooth powder or toothpaste with the addition of clay not only whitens the teeth even of heavy smokers and coffee drinkers, but also removes tartar, strengthens enamel, and reduces the threat of caries.

The darker the color of the clay, the better it will remove fat and deal more effectively with acne.

Blue cosmetic clay

This clay has anti-inflammatory properties and contains all the mineral salts and trace elements we need. It can prevent the appearance of acne and effectively accelerate the healing of skin wounds. This clay is great for cleansing facial skin and improving its color. Blue clay is also used to smooth out facial wrinkles. It rejuvenates the skin, making it firmer and more elastic. Blue clay can also lighten freckles and age spots. When used regularly, this type of clay can be a great help for problem skin. It disinfects and smoothes the skin, eliminates acne. Activates blood circulation and accelerates the metabolic process in skin cells. In addition, traditional medicine uses blue clay as a very effective remedy against baldness. Moreover, blue clay softens and tones the skin, and also has anti-cellulite, antibacterial and anti-stress effects. Foot masks based on blue Cambrian clay helped to improve the microcirculation of the skin of the lower extremities, which was expressed by increasing the firmness and elasticity of the skin, reducing swelling and the severity of the “feeling of heaviness in the legs.” Due to the high adsorption capacity of Cambrian clay, using a foot mask in the foot area for 20 minutes 1-2 times a week helps reduce the degree of sweating of the feet, eliminates unpleasant odor and can be used as a preventive measure for fungal and bacterial infections of the skin of the feet.

Green cosmetic clay

Green clay gets its color from iron oxide. Taken directly from the quarry, green clay appears as a dark green, wet mass. This clay has found wide application in cosmetology. It can be the basis for cosmetics, and also comes in the form of masks, wraps and compresses. Due to the content of a large number of microelements, it helps restore the skin's hydrobalance and has remarkable absorbent properties. Green clay softens and cleanses facial skin. It relieves irritation and has a drying effect. Green clay masks perfectly cleanse facial pores and eliminate oily shine. In home facial treatments, you can mix green clay with another type of clay.

Green clay has excellent absorbent properties. This is an ideal product for deep skin cleansing. Best suited for oily skin of the face and scalp, used to combat seborrhea. Helps narrow pores and improves the function of the sebaceous glands. Has excellent tonic properties. Causes blood flow to the surface of the skin and provides it with the necessary nutrition. Stimulates skin cell regeneration. Tightens the skin and restores the facial line. Effectively softens, smoothes wrinkles and relieves puffiness. Restores normal metabolism and has antibacterial properties, as it contains a large amount of silver. Baths with green clay cleanse and soften the skin, pleasantly relieve fatigue, stress and irritation due to its natural ability to remove all the negative energy accumulated during the day.

Red cosmetic clay

Red clay is this color due to a combination of iron oxide and copper. It is best suited for women with sensitive skin prone to allergic reactions. Masks made from this clay relieve irritation and redness on the face. They will also help get rid of flaking and itching of the skin. Red clay can also be used for dry, dehydrated skin. It will help aging and dull skin. This type of clay improves blood circulation and increases the saturation of facial skin with oxygen. It is also used for iron deficiency in the body - taken orally.

When rubbed into the scalp, red clay strengthens weak and brittle hair, nourishes hair follicles and treats oily seborrhea. The components of red clay effectively nourish and restore tired skin, help smooth out premature wrinkles, and also have the effect of “educating” involuntary facial expressions, especially in the forehead area.

Pink cosmetic clay

Pink clay does not exist in nature; it is the result of mixing white and red clay. This clay is perfect for caring for any skin type. Smoothes out small wrinkles, softens the skin, tightens the facial contour. Pink clay has a rejuvenating effect. Nourishes and cleanses the skin, makes it softer and gives elasticity. In addition, it is widely used in masks and applications for weakened hair and nails. Has a refreshing and restorative effect. Pink clay baths moisturize the skin, relieve fatigue, have a tonic effect and improve metabolic processes in tissues, creating a feeling of freshness and comfort.

Yellow cosmetic clay

Yellow clay contains a lot of potassium and iron, as well as a number of other rare trace elements. It saturates the skin with oxygen. Has a tonic effect. Quickly, effectively and permanently improves complexion. Nourishes hair and scalp, helps get rid of dandruff. Yellow clay is able to absorb waste products of the body and kill pathogenic bacteria. It saturates the skin with oxygen and removes harmful toxins during various inflammatory processes, including acne. Yellow clay is perfect for aging and tired skin. It smooths out wrinkles, softens and cleanses the skin well, gives it elasticity and freshness. Yellow clay also exfoliates dead skin cells, softening rough skin on the hands, elbows and feet; promotes healing of small cracks. Due to its high adsorption capacity, yellow clay effectively relieves sweating of the feet and eliminates their unpleasant odor. Yellow clay baths relieve fatigue after physical activity, improve metabolic processes in tissues, improve the condition of the skin, making it smooth and velvety.

Black (gray) cosmetic clay

Black clay contains strontium, quartz, iron, magnesium and calcium. It cleanses the skin very well. This type of clay can perfectly absorb all harmful toxins and impurities from the skin. Helps tighten facial pores. Suitable for normal, oily and combination skin.

The most active among all types of clays, it is mined at sea depths. This is one of the most powerful remedies in the eternal women's fight against cellulite and fat deposits. Black clay is used to nourish dehydrated, dry skin. It also relaxes tired muscles, relieves rheumatic pain and effectively fights bruises.