What ceramic dishes are made of. Ceramics. Technology for making ceramics at home. Manual processing of products

The art of ceramics- making various items from clay - an ancient type of folk craft. From time immemorial, ceramics have served people. They differed in the type of raw materials used, the composition of the glaze coatings, the production method, and their purpose. Wherever there were natural reserves of clay suitable for processing, master potters created flower pots, bowls, jugs, dishes, flasks, vases and many other items necessary in everyday life of various shapes and decorations.

The plasticity of the material, its tonality, the coloristic variety of glazes, giving the items a variegated and rich color, contributed to the fact that ceramic items performed not only a purely utilitarian function, they became works of art. The ceramics of different eras are marked by the characteristic features of their time. Interest in her has been preserved in our time. Popular folk art craft

Nowadays, ceramics are widely used in the interior in the form of decorative partitions, lattices. Fireplaces are made of ceramic bricks. Ceramic reliefs, ornamental and thematic panels, candlesticks, decorative vases, vessels, bowls, flower pots, used both as individual items and in compositions that create a special mood and coziness, also serve as decoration. Vases of various shapes and sizes are very popular, wall ceramics - decorative dishes, plates, layers. With a skillful selection of such ceramic items, they fit well into the interior and complement it.

The main technological types of ceramics are majolica, terracotta, fireclay, porcelain, faience. They differ in the composition of clays, firing mode, and decoration techniques.

Chamotte- used to create decorative vases, reliefs, decorative sculpture. These products are distinguished by a beautiful grainy texture, and decorating with glazes gives them a unique flavor.

Porcelain- a mineral mass from a fine mixture of kaolin, plastic clay, quartz, feldspar. Porcelain products are distinguished by their whiteness, thinness (thin shard), transparency. They do not allow liquid to pass through, even when not glazed. Faience is close to porcelain, but does not possess its whiteness and transparency, its shard is thicker, not glazed, it allows moisture to pass through. Porcelain and earthenware products are primarily dishes, as well as decorative items - vases, dishes, various compositions, etc.

Faience - a ceramic shard, due to its porosity, is susceptible to the destructive effect of a humid atmosphere, especially with sharp temperature fluctuations. To eliminate this, the ceramics are covered with glaze (glaze) - a glassy composition that fills all the outer pores of the ceramic product and gives it some shine. The glaze is prepared in different ways, depending on the composition of the mass for which it is intended. Distinguish between hard glaze (containing feldspar, etc.) and soft (containing lead or boric acid). The objects are glazed either with a wide brush or directly dipped with tongs into a solution of glaze, which the porous clay quickly absorbs into itself, and then fired. Painting on hard glaze is always somewhat dry, so you can immediately notice that it is made over glaze, while painting on soft glaze is sometimes difficult to distinguish from underglaze painting.

The invention of watering, like many other discoveries, is due to the ancient East. Glazed or glazed - they covered beads made of soft steatite stone in Egypt back in the Neolithic era. The effect of irrigation, which makes the earthen vessels shiny and impervious to moisture, was discovered and appreciated later. The irrigated friezes of Assyria, Babylonia and Achaemenid Persia were landmarks of this difficult path. He was very uneven, epochs of enthusiasm were replaced by epochs of almost complete oblivion, but the East always showed more interest in bright irrigation products. Greece, a contemporary of the Persian kingdom, did not know them at all.

The new flourishing in the production of glazed ceramics, which began in the Middle Ages, again turns out to be associated with the countries of the Middle East. The most perfect examples of such products belong to the peoples united by the Arab Caliphate. The secrets of the production of glazed ceramics were entered by medieval scholars on the pages of their works, and she herself was kept in the treasuries of the caliphs along with precious stones, clothing and weapons.

The expansion of the territory of its distribution was no less important for the medieval stage in the history of glazed ceramics. Much credit for this belongs to Byzantium, which managed to inherit the experience of the East and Rome and to acquaint with it, already in its bold incarnation, the young civilizations of Europe entering the world arena. IX - X centuries. The northern Black Sea region becomes a place of lively trade between Russia and Byzantium. Kherson played an important role as a mediator in it. From here, Byzantine glazed ceramics came to ancient Russia. These were white clay dishes with embossed images on the bottom, covered with bright green speckled glaze.

With the development of trade relations, as a result of resettlement, wars, the influence of borrowing and imitation of neighbors becomes more and more noticeable. During the movement of the Mongol tribes in Central Asia, the techniques and artistic features of Chinese ceramics were adopted in Persia, from which, in turn, they were borrowed by the tribes who lived in Arabia. Later, with the spread of Islam, the influence of the Persian style affected the Moors who conquered Spain in the 9th century. Thus, this style was brought to Western Europe.

The word "faience" comes from the Italian city of Faenza, famous for its faience production. Most likely, this art came there along with the Arabs - through Spain, where they made beautiful Spanish-Moorish glazed ceramics. The Bolear Islands were also engaged in the production of enameled clay products, and, in all likelihood, the word "majolica", also used to designate Italian artistic faience, owes its origin to the name of one of these islands - Mallorca. Luca della Robia (15th century), a famous Florentine ceramic sculptor, is considered the man who discovered and first applied tin, opaque, dull, milky-white glaze.

He became an ingenious master of fine glazed ceramics in the 16th century. French sculptor Bernard Pallisi. A simple potter, he became a geologist and agronomist, physicist and chemist, garden architect and writer, glass painter. In France then they did not know how to make faience and enamel. Palissy decided to reveal the secret of their manufacture. He found a way of making multi-colored glaze, transparent, very beautiful, of good quality, and began to make dishes and plates of oval shape, shallow, with straight wide edges. Harmony of colors, amazing watering skillfully portrayed nature. Palissy himself called his faience "rural clay".

France owes its wide use of faience to the "sun king" Louis XIV. Having devastated the treasury with endless wars, in order to save money, he banned the use of silver dishes. In 1700, the king replaced his gold cutlery with faience. They began to buy up earthenware in the shops, it became fashionable, which was the impetus for its production in France. The centers of ceramics were the cities of Rouen, Nevers. In Rouen, they made blue and red faience - the secret of the Norman ceramists - and the dishes were bright yellow, with almost black thin arabesques.

In Russia, earthenware began to be produced at the end of the 18th century. For the first time - at the state-owned Kiev-Mezhigorsk plant, and then at other state and private enterprises. In the XIX century. earthenware has become the most commonly used ceramic tableware. Modern factories produce hard feldspar earthenware with a very resistant glaze. It consists of two-thirds or a half of clay substances; usually a tenth of it is feldspar, the rest is quartz. This is the strongest faience. Ancient earthenware is softer, it consists of more than three-quarters of clay and is not very thermally stable. The "body" of earthenware is mainly plastic clays (white or light-burning) and kaolin is a loose, soft clayey white rock. There are large deposits of kaolin in Ukraine: these are the well-known deposits of Belaya Balka, Glukhovetskoe, Prosyanovskoe.

Ceramic products and materials classified according to purpose and properties, according to the main raw materials used or the phase composition of sintered ceramics. Depending on the composition of the raw materials and the firing temperature, ceramic products are divided into 2 classes: fully sintered, dense products, shiny in a fracture with water absorption not exceeding 0.5% and porous, partially sintered products with water absorption up to 15%. A distinction is made between coarse ceramics, which have a coarse-grained structure that is non-uniform in the fracture (for example, building and fireclay bricks), and thin ceramics with a homogeneous, fine-grained fracture and uniformly colored shard (for example, porcelain, faience).

The main raw materials in the ceramic industry are clays and kaolins due to their wide distribution and valuable technological properties. The most important components of the initial mass in the production of fine ceramics are feldspars (mainly microlines) and quartz. Feldspars, especially pure varieties, and their intergrowths with quartz are mined from pegmatites. In increasing quantities, quartz-feldspar raw materials are extracted from various rocks by enrichment and purification from harmful mineral impurities. However, the increased and sharply differentiated requirements for ceramics by metallurgy, electrical engineering, and instrument making have led to the development of the production of refractories and other types of technical ceramics based on pure oxides, carbides, and other compounds.

The properties of some types of technical ceramics differ sharply from the properties of products made from clays and kaolins, and therefore the unifying features of ceramic products and materials remain their production by sintering at high temperatures, as well as the use in production of related technological methods, which include: processing of raw materials and preparation ceramic mass, production (molding), drying and firing of products.

According to the method of preparation, ceramic masses are divided into powdery, plastic and liquid. Powdered ceramic masses are a mixture of crushed and dry-mixed initial mineral components, either moistened or with the addition of organic binders and plasticizers. By mixing clays and kaolins with lagging additives in a wet state (18-26% water by weight), plastic molding masses are obtained, which, with a further increase in the water content and with the addition of electrolytes (peptizers), turn into liquid ceramic masses (suspensions) - foundry slips.

In the production of porcelain, earthenware and some other types of ceramics, plastic molding mass is obtained from the slip by partial dehydration in filter presses, followed by homogenization in vacuum mass crushers and screw presses. In the manufacture of some types of technical ceramics, the casting slip is prepared without clays and kaolins by adding thermoplastic and surfactants (for example, paraffin, wax, oleic acid) to the finely ground mixture of raw materials, which are then removed by preliminary low-temperature firing of products.

The choice of the ceramic molding method is mainly determined by the shape of the products. Products of a simple form - refractory bricks, facing tiles - are pressed from powdery masses in steel molds on mechanical and hydraulic press machines. Wall building materials - bricks, hollow and facing blocks, tiles, sewer and drainage pipes, etc. - are molded from plastics in screw vacuum presses by extruding a bar through profile nozzles. Products or workpieces of a given length are cut from the bar by automatic machines synchronized with the operation of the presses. Household porcelain and faience are formed mainly from plastics in plaster molds on semiautomatic and automatic machines.

Sanitary construction ceramics of complex configuration are cast in plaster molds from ceramic slip on mechanized conveyor lines. Radio and piezo ceramics, cermets and other types of technical ceramics, depending on their size and shape, are made mainly by pressing from powdery masses or by casting from paraffin slip in steel molds. tunnel or conveyor dryers.

Firing of ceramics is the most important technological process that ensures the desired degree of sintering. Accurate adherence to the firing regime ensures the required phase composition and all the most important properties of the ceramics. With rare exceptions, sintering of crystalline phases occurs with the participation of liquid phases formed from eutectic melts. Depending on the composition of the ceramic mass and the firing temperature in porcelain, steatite, and other densely sintered items, the content of the liquid phase in the sintering process reaches 40-50% by weight or more. The forces of surface tension arising at the interface between the liquid and solid phases, the grains of the crystalline phases (for example, quartz in porcelain) approach each other, and the gases distributed between them are displaced from the capillaries. As a result of sintering, the dimensions of the products decrease, and their mechanical strength and density increase.

Sintering of some types of technical ceramics (for example, corundum, beryllium, zirconium) is carried out without the participation of a liquid phase as a result of bulk diffusion and plastic flow, accompanied by crystal growth. Sintering in solid phases occurs when using very pure materials and at higher temperatures than sintering with the participation of a liquid phase, and therefore has become widespread only in the production of technical ceramics based on pure oxides and similar materials. In accordance with the set of requirements imposed, the degree of sintering of different types of ceramics varies within wide limits.

Products made of electric porcelain, porcelain, earthenware and other types of fine ceramics are covered with glaze before firing, which melts at high firing temperatures (1000-1400 0C), forming a glassy water and gas impermeable layer. Glazing increases the technical, decorative and artistic properties of ceramics. Massive products are glazed after drying and fired in one step. Thin-walled products are pre-fired before glazing in order to avoid soaking in the glazing suspension. In some ceramic industries, the unglazed surface of fired products is ground with abrasive powders or an abrasive tool. Household ceramics are decorated with ceramic paints, decals and gold.

How to explain the attractive power of the "painted shards"? Perhaps the secret is that a vase, pot, plaque, sculpted by the sensitive hands of a master, absorb human warmth. The poetics and beauty of ceramics made it an integral part of all eras, all cultures.

Wall ceramic panels... Monumental ceramic wall panels transform an ordinary room into a unique, one-of-a-kind, create a sense of respectability and stability. It is not for nothing that many high-level international organizations have decorated their halls with ceramic panels! Ceramic tile painting or ceramic relief can be done in a wide variety of styles. Any fantasy can be embodied in wall panels: historical and fairy tales, folk motives, color and geometric abstractions. Traditionally, ceramic panels are used as artistic decoration of walls in halls, lobbies, foyers. The wall panel looks very impressive in the pool, reflected in the blue mirror of the water.

Ceramic inserts. Inserts are called small ceramic wall paintings. Like a panel, it can be painted on ceramic tiles or ceramic reliefs. The inserts can be framed with a forged metal or wood frame, and then they will look like paintings. Ceramic inserts look good on any wall finish.

Bulk ceramics. Have you ever wondered what has come down to us from ancient cultures? That's right, ceramic dishes - pots, vases. In interiors, ceramics are eternal. With a thousand-year history behind it, it will never go out of style.

Vases are the art of ceramics at its finest. Smooth, flowing lines of vases organically fit into any interior, reflect the taste of the owner and set the tone for the house

Planter for planting plants- an example of functional ceramics. The decorativeness of a palm tree, lemon tree, ficus will increase many times if they are placed in ceramic pots. Elements of the winter garden take a special place in interior ceramics. They give originality and originality to the corner where the green oasis is located. Souvenir sculpture. Bright, colorful figurines of animals, birds, funny characters from fairy tales not only decorate the room, but also create a festive mood.

Wall plates and plaques. Ceramic plates and plaques serve as a wonderful memento in honor of an anniversary or other significant event. At the same time, they can serve as decorative ornaments. Plates and plaques depicting the city's view or coat of arms, a memorial sign, and a logo are very popular.

Ceramic vases, pots, tea sets, candlesticks, plates, whistles and even musical instruments can all be created by yourself.

To learn how to make ceramics with your own hands, the main thing is desire. Before becoming a ceramist, try to mold the simplest trinket out of clay, and you will understand whether it is worth spending money on buying equipment for the job. If something doesn't work out, it doesn't matter, soak the marriage and make a new figure out of it, before baking the product can be endlessly modified.

What ceramics are made of and where to get materials for work

Ceramics is fired clay, which is the main material in the work of a ceramist. In contrast, natural is of natural origin, it is mined from the bowels of the earth, without being subjected to chemical and other types of processing.

In order to save money, experienced craftsmen extract and prepare raw materials on their own. This process includes several stages and hardly deserves attention if you are just starting your journey and live in a city.

Clay for making ceramics must be greasy and free of inclusions of stones and other debris, otherwise the craft will crack during the baking process. The finished mass is stored under certain moisture conditions.

Natural clay happens different types:

• White is the most common, initially has a grayish tint, and after heat treatment takes on a pleasant ivory tint.
• Red - contains iron oxide, which gives the raw material a greenish tone. The main color of the raw material is brown; after firing, the products turn red. It lends itself well to sculpting, does not crumble, ideal for sculptures and large items.
• Porcelain - gray raw and white after baking.
• Blue - is more often used in cosmetology and traditional medicine.
• Black or dark brown ceramic mass is the hardest clay, acquiring an ivory hue after being processed in an oven.

Also clays for ceramics classified by temperature processing for low-melting, medium-melting, refractory.

It is most convenient to buy ready-made pottery clay, focusing on the size of the fraction, color after firing at different temperatures and other characteristics and quality indicators. The cost depends on the manufacturer, packaging, texture. There are ready-made masses with additives to facilitate various tasks - sculpting, molding, potter's wheel.

In addition to clay, you need glazes and enamels to cover products, pigments to give your hand-made ceramics the desired shade, special additives to improve properties and heat treatment.

For gluing parts use slip mass- a kind of glue made from diluted clay. If you simply connect the elements, they can fall off when heated. All this is sold in specialized stores for ceramists.

Methods for making ceramic products

There are several ways to turn a clay mass into a beautiful pottery.

Molding- the most affordable way of making ceramics with your own hands at home. Souvenirs, sculptures, dishes, toys or other crafts are molded by hand, as if from plasticine, helping themselves with special stacks or improvised devices.

Pottery requires a rotating circle. With the help of this ancient craft, vases, jugs, pots, plates, cups are still being created today.

Workout- the easiest way to make ceramics for beginners. In the work, a plaster mold is used, in which soft clay is laid out, and after hardening, a figured product is removed. Plaster molds are attractive because they absorb excess moisture, helping the clay product to harden and dry.

Casting- here they also use forms, but of a different plan. The diluted clay is poured into molds, the blanks are dried, removed and painted.

Clay craft gains strength only after firing - processing in pottery kilns at temperatures from 900 to 1300 degrees. Finished souvenirs are coated with acrylic paints or special glassy glaze for ceramics. In the case of glaze, an additional firing is required after staining.

If you want to get a natural shade, use milk firing - cover the unpainted ceramic figurine with milk in several layers and bake it again at lower temperatures.

Pottery kiln - types and preferences

Previously, ceramics kilns were forges dug in the ground and were heated exclusively with wood. Modern pottery kilns are gas, electric and wood-burning. The latter, as a rule, are made with their own hands, they are suitable for use in private households. In the conditions of an apartment, it is most convenient to work with electric furnaces; for large volumes, you can choose a gas one.

Refractory bricks or other material that retains heat and is not afraid of heating is hidden in the metal body of such furnaces. To remove moisture, ventilation holes are provided, the process of ceramics firing is controlled by a software controller. Electric pottery ovens are not cheap. The price depends on the manufacturer, volume, power.

On sale there are models with vertical and horizontal loading and bell-type ones. By the type of location of the heating element, pottery kilns are divided into muffle and chamber kilns. V muffle it is located around a container made of refractory material (muffle). In the chamber, the heater is located inside, which reduces heat loss and makes the equipment more economical.

If you try a little, you can make a do-it-yourself oven for firing ceramics at home, taking as a basis refractory bricks and something for the body, for example, an old washing machine.

Baking is the most important and unforgiving process. Sometimes even experienced craftsmen see a bad marriage instead of the expected masterpiece. The items are never taken out immediately, they must cool in the oven.

How to choose a potter's wheel

Pottery wheels are used to sculpt round objects, so this tool does not have to be purchased right away. If you are just learning ceramics, start by sculpting or kneading. Circles are available with manual, foot and electric control.

In the history of mankind, there are many materials that accompanied people almost from the very beginning of civilization. Wood comes to mind first, but do not forget about ceramics - fired clay, from which dishes have been made from time immemorial.

Such a material has enough positive qualities: the ceramics are durable, resistant to chemical and high-temperature influences, are distinguished by complete environmental safety, and with their appearance everything is in order. In addition, the tile does not rot and does not become covered with fungus, which allows it to be successfully used for finishing a wide variety of technological rooms and bathrooms.

In general, ceramics are dishes or other things made of clay (with or without mineral additives) obtained by molding and subsequent high-temperature firing. To make the appearance of such products more beautiful, they are glazed.

What materials can be used in production?

We have already said that clay is mainly used for these purposes, but there are exceptions. So, the following materials can be used for ceramics:

• Plastic base. This is just the same clay or kaolin (a rock consisting of kaolinite).
• Materials that minimize settling during firing help maintain the shape of the product. High-quality quartz sand, substandard porcelain (battle), fireclay are used.
• Rocks that give a dense glassy mass when sintered. Feldspar, pegmatite are ideal.
• Glaze. Can be used as a material from natural raw materials, and numerous analogs obtained by chemical synthesis.

Classification

So we learned that ceramics is a specially processed clay. The factors that predetermine the consumer qualities of the product are the type of ceramics, the way it is decorated or molded.

A distinction is made between fine ceramics (fine grain size at the fracture of a shard) and coarse (coarse grain size). Of the subtle varieties, each is familiar with porcelain, semi-porcelain, and earthenware, tiles from which can be found in almost every bathroom. Accordingly, rough ceramics (you will find a photo in the article) are pottery pots. The thing is not very common in our country, but it has been known since the deepest antiquity.

Properties of different types of ceramics

The hallmark of porcelain is a thin, dense and white fine-grained shard. The material absorbs moisture very poorly (up to 0.2%). Valuable vases or cups (very thin) can be viewed by light. The edges of the side (usually the bottom) are not covered with glaze due to the firing technology. For production, mainly kaolin is used and

Semi-porcelain is an intermediate option between the above-described porcelain and faience. Somewhat coarser, water absorption from 3 to 5%, is most often used in the manufacture of household utensils.

As for the faience itself, it is distinguished by a thick porous shard, which, when broken, has a slightly yellowish tint. The ability to absorb water is high, in the range of 9-12%. It is because of this, as well as because of the high porosity, that any ceramic products of this type are necessarily covered with a layer of thin glaze.

Since the glazing used is very unstable to thermal influences, this type of ceramics is used exclusively in the production of inexpensive everyday utensils, as well as for household containers. For dressing, they take not very high-quality varieties of clays, chalk and quartz sand. The technology of this type of ceramics also allows the use (as a base) of broken porcelain. Of course, before starting production, it is crushed and finely ground.

Majolica is a very attractive ceramics. The price for it is about a thousand rubles for an average vase. A distinctive feature is a very porous shard, it can absorb up to 15% moisture. Despite this, the products are distinguished by thin shiny surfaces and have a small wall thickness. The latter is due to the fact that majolica is made using casting technology. As a rule, products are decorated with glazing; decorative bas-reliefs are also often found. In the production of this type of ceramics, white-burning clays, quartz sand, chalk and flux are used.

Pottery ceramics (photo of which is in the article). It is distinguished by a shard of a specific red-brown color (red-burning clays) and a very high porosity. Moisture absorption coefficient - up to 18%. For coloring, special clay paints, engobes are used. To protect them from moisture, the products are covered with a thin layer of colorless glaze on top. As for the scope of use, the assortment is represented not only by decorative pots, but also by quite practical utensils for the household.

In addition, warm ceramics belong to the same category. This is the name of the bricks made of coarse fired clay. In the production of this kind of ceramics, special foaming agents are used, which sharply increase the porosity of the material, and therefore its thermal insulation qualities become much better.

How is the production process going?

The production of ceramics itself can be easily divided into the following several stages:

• Extraction and appropriate preparation of raw materials.
• Shaping, decorative patterns or functional holes.
• Casting, semi-dry stamping.
• Editing, first drying.
• High temperature processing.
• Frosting.
• Reburning.
• Decorative processing (warm ceramics and analogues do not need it).

The quality indicators of the finished product are determined by the characteristics of the appearance, full compliance with the functional purpose, as well as durability.

Manufacturing technology

We talked about the main stages of production, and therefore now let's discuss each of them separately. To prepare the initial ceramic mass, the following technological operations are performed: the raw material is thoroughly cleaned of foreign mineral and organic impurities, crushed and ground. After that, it is the turn of mixing and adding various additives.

Product shaping

Forming is carried out from liquid or plastic ceramic masses. Plastic molding has a number of advantages. First of all, this is expressed in the fact that you can make products of almost any shape and size. In addition, even the simplest and most technologically advanced equipment can be adapted for their manufacture.

As for casting, a mass with a moisture content of 34-36% is used for this. Pouring is done in plaster molds. This is an indispensable method for the manufacture of truly complex ceramic products, the shape of which physically does not allow the use of other molding methods. In addition, tiles are produced in this way. Ceramics for it are not made from the best types of clay (below the requirement), but the thickness of the finished products should be as uniform as possible.

Casting can be either manual or fully automated. After the initial drying, the products are removed from the molds, after which various decorative and functional elements are glued, for which special glue is used. In the past, clay dough was used for this purpose, but it did not provide very high strength.

Drying

Drying is the most critical stage, since both the mechanical strength of the product and its decorative characteristics depend on the correctness of its implementation. Of course, the correct distribution of the glaze is also extremely important, on which the resistance of products to water and chemical agents depends. Drying is a prerequisite for the production of ceramics. For it, conveyor, radiation and chamber dryers are used. The temperature throughout the entire process should not exceed 70-90 ° C.

The only exception is the tiles. In this case, the ceramics are very thick, so in some cases it is allowed to use the high-temperature regime for a short time.

Burning

The second most important technological stage is ceramic firing. The goal is to form a shard with precisely specified physicochemical properties, to fix the coloring composition and glaze on the surface. Firing is important because many physical and chemical processes take place during its course, which predetermine the main consumer qualities of the product. Usually firing is carried out in two stages, but if paint has been applied to the glaze surface, the so-called muffle firing is carried out (third stage).

The first stage is carried out at temperatures from 900 to 1250 ° C (depending on the type and grade of ceramics). The second stage requires a temperature regime from 1020 to 1410 ° C. The latter value is used exclusively for porcelain. Other ceramics are rarely fired in this mode, as there is a high risk of cracking. If we are talking about the average red clay, then products made from it are often "burned" once, at a temperature not higher than 960-1020 degrees Celsius.

For firing, ceramic kilns of two types can be used: periodic (forges) and also continuous. There are a lot of varieties of the latter, but tunnel and roller ones are most common.

About various defects

The specificity of the manufacture of ceramic products lies in the fact that at various stages of production, a large number of a wide variety of defects may occur. There is damage to the shard, glaze or decorative coating. As for the defects of the shard, they most often appear at the stage of primary molding and initial drying.

Some part of the manufacturing defect appears almost immediately, and spots or something similar appear only after firing. Due to the “capriciousness” of the final product, there is a requirement to strictly control the purity of all tools used in production.

Description of basic concepts

Glaze is a special melt that is applied to the surface of the finished product. Their thickness is 0.12-0.40 mm. The purpose of glazes is quite varied. Firstly, the surface of a tile or crockery is covered with a dense decorative layer, which not only contributes to the appearance of a pleasant appearance, but also significantly increases the mechanical strength. In addition, the coating provides reliable protection against physical and chemical influences, which is especially important for household utensils.

Decorating refers to the application of decorative paint or patterns. Often in the conditions, figured stamps are used, with the help of which mass production of the same type of products. A stamp roller is used to pattern the edges of the pot. Accordingly, the final operations consist in the elimination of minor defects, grinding the legs and edges.

Some information about glazes and paints

Glazes are divided into transparent and opaque varieties, they are colored and completely colorless. Ceramic paints are used to decorate almost all types of fired clay products. They are based on either metals or their oxides. When heated, they form stable compounds that are not only beautiful, but also very durable. Such ceramics, the reviews of which are always excellent, have long been an adornment in many wealthy homes.

Paints are divided according to the method of their application: either on the glaze layer, or under it. As you can understand, in the latter case, the coloring composition is applied directly to the shard. Only then is it covered with a layer of glaze, and the product is fired in the oven. If the composition is applied directly to the glaze layer, it is fixed at a temperature of at least 600-850 ° C.

As for the auxiliary materials, they are used to make molds for firing and casting.

Information about the manufacture of casting molds

To make sufficiently strong and high-quality forms, molding plaster is used. It is made by finely grinding the powder of calcium sulfate hemihydrate. The peculiarity of such gypsum is that when mixed with water, it should turn into a sufficiently plastic and elastic dough. But the main thing is that this composition must be set within precisely defined terms, which guarantees a really high-quality firing. If gypsum is not available for some reason, carborundum can be used. The use of other refractory materials is allowed.

This is the kind of material without which it is impossible to imagine any kitchen or bathroom. However, there is another variety of it, products from which can be real decorations for any home.

Artistic ceramics

"Artistic" refers to products decorated with a particularly delicate relief or stucco molding. Of course, there are practically no other differences from ordinary ceramics, but there are many subtleties in the manufacturing technology. We’ll talk about them now.

Initial preparation of raw materials

As you can imagine, artistic ceramics are not much different from their “everyday” counterparts, but when making it, you need to be more demanding in the selection of raw materials. Everything is the same as in the previous case, but all operations are performed more subtly. In addition, use extremely finely ground kaolin (particle diameter less than 2 µm).

What does it do? This approach allows you to get a much more plastic mass, and also at least doubles the strength of dried products. In addition, you should take only small ones, as it sharply reduces the draft of the finished product, which is extremely important for artistic ceramics.

Drying of artistic ceramics

As we mentioned in the first part of the article, drying is one of the most important stages. If we talk about artistic ceramics, then this statement becomes even more relevant. You should be aware that shrinkage occurs unevenly during firing of thin products, which can lead to big troubles, up to damage to the entire product. Therefore, it is extremely important to choose the correct heating mode so that artistic ceramics do not turn into a heap of shards.

If the products are flat, then it is strongly advised to dry them exclusively in molds. First, they are slightly dried until the future ceramics acquire the required density, and only after that it can be removed and dried to a moisture content of 1-2.5%.

To carry out this process in large quantities, special conveyor dryers are used. In particularly difficult cases, drying is carried out in devices that operate on a batch basis. This is done in order to prevent fine ceramics from drying out and cracking. Drying times range from 30 minutes to three hours.

So you learned what ceramics is. It is one of the oldest materials ever produced by mankind. Despite its antiquity, ceramics are in great demand to this day.

Ceramic products, like glass products, are included in the group of silicate products. Ceramic products are products made mainly of clay materials and fired to impart strength.

Depending on the firing temperature, as well as the composition of the mass, a shard of ceramic products can turn out to be porous or solid (sintered). To make the surface of ceramic products smooth, easy to clean and not absorb moisture, it is covered with a glaze, which is a thin layer of glassy mass.

What is made of ceramics?

Depending on the purpose, ceramic products are distinguished: industrial and construction, technical, household and artistic and decorative.

Industrial-building and technical ceramics include bricks, tiles, stove tiles, facing and floor tiles, etc.

The composition of household and artistic and decorative ceramics includes pottery, as well as dishes and decorative items made of porcelain, earthenware and majolica.

Pottery is a pottery made from simple colored clay. It can be glazed or unglazed.

Porcelain and earthenware are products with a white, usually glazed shard, and in porcelain it is solid, sintered, and in faience it is porous.

Majolica is the name given to products with a porous shard of white or lightly colored clays, having a relief pattern on the body and covered with colored glaze.

Pottery belongs to the so-called rough ceramics, and porcelain, earthenware and majolica - to fine ceramics.

Raw materials for ceramic products

The main raw materials for the production of ceramic products are plastic materials, emaciated materials and fluxes, or fluxes.

Plastic materials. The plastic materials used in ceramic production include various types of clays and kaolin (a clayey substance that is usually white in color, consisting almost entirely of kaolinite). Clays, depending on the impurities they contain, can have different melting points and different colors, and in cases where this color is caused by the presence of organic impurities, such clays acquire a white color during firing (the so-called white-burning clays).

Clay and kaolin have the property of plasticity, that is, the ability to give dough when mixed with water, acquire any shape under external influence and maintain this shape.

After firing, the clay and kaolin obtain the hardness of the stone, turning into a shard that no longer possesses plasticity and, when mixed with water, does not give a plastic dough. These two properties explain the widespread use of clay materials in the manufacture of various products.

Lean materials... Leaning materials are used in ceramic production to reduce shrinkage of products, since high and uneven shrinkage of products made from one clay during drying and firing causes deformation and cracking of these products. Such emaciated materials include quartz sand, quartz, broken shards (broken pottery), etc.

Float. Fusions are added to facilitate sintering of the constituent parts of the ceramic mass. Naturally, floodplains are of particular importance in the production of items with a sintered shard (porcelain, etc.). The floodplains include feldspar, chalk, limestone.

Pottery

Pottery is made from natural colored clays containing up to 20% sand, or from a mixture of pure clays with an appropriate amount of sand.

To increase plasticity and release from foreign impurities, pottery clay is often frozen, sieved, sometimes elutriated.

Products are formed from prepared clay dough, most often by hand on rotating, so-called pottery, circles, sometimes using templates. Products of complex shapes are made by hand molding or in plaster molds.

The molded products are dried, then, as a rule, glazed and fired at 900-1000 °.

Glaze on pottery is a low-melting glassy mass that makes the surface of pottery smooth and impervious to moisture.

Pottery is glazed in various ways, but most often by dipping the products into a suspension (chatterbox), which is a suspension of finely ground glaze in water, or by pouring glaze into the products for a certain period of time. In this case, moisture is absorbed into the walls of the products, and the glaze particles settle (suck) on their surface and during the next firing of the products they melt, turning into a glassy mass, which is melted to the walls of the products.

Pottery is most often produced without decorations, but some of its types (jugs, vases, wall dishes) can be decorated. Such products are most often painted with engobes and colored glazes before glazing.

The assortment of pottery includes: pots, milk jugs, jugs, bowls, dishes, mugs, vases, etc.

Pottery produced at the enterprises of the Ministry of Local Industry is divided into 1st and 2nd grade; handicraft ware is usually produced in one grade. The good quality of the pottery is checked by visual inspection and tapping. An external examination establishes the correctness of the form and the accuracy of the glazing. By tapping, check the integrity of the dishes (cracked dishes rattle) and the quality of firing (well-fired dishes, when struck, make a high, clear sound).

Porcelain and earthenware

Materials and production

Porcelain and earthenware dishes are made mainly from a mixture of kaolin, white and white-burning clays, quartz and feldspar. Ground porcelain and earthenware are also used.

The mass for porcelain most often contains 50% clay materials, mainly kaolin, 25% quartz and 25% feldspar. The mass for earthenware includes 5-10% feldspar, 35-40% quartz and 50-60% clay materials (mainly white clay). Thus, the main difference between porcelain and earthenware is the higher content of feldspar and kaolin.

The production of porcelain and earthenware dishes is much more complicated than the production of pottery. It consists of. preparation of the mass, molding, drying, double firing, glazing and painting.

Prepare the mass for porcelain and faience very carefully. Quartz and feldspar are roasted, washed to free from impurities, roughly ground, then their mixture with coarsely ground beating is thoroughly ground in special ball mills. The resulting mass is mixed with clay materials, passed through an electromagnet to remove iron impurities, through a filter press to remove excess moisture and, finally, through a mass mill to obtain a homogeneous mass, which is kept for some time in basements, and then transferred to molding.

Porcelain and earthenware dishes are molded using molds and templates or by casting into plaster molds. In the first case, products are molded from porcelain or earthenware dough in rotating plaster molds (hollow or convex) using templates. In this case, the plaster mold forms one of the surfaces of the product, and the template, the edge cutout of which corresponds to the shape of the other surface, evens out this surface of the product. In the second case, the liquid mass (slip) is poured into plaster molds having an internal cavity corresponding to the outer surface of the product.

A significant part of the moisture is absorbed from the slip by thick walls of a gypsum mold, and particles of the mass remain on the surface of its walls, forming the walls of the product. Excess slurry is removed and the product is taken out of the mold after drying.

The molded products are dried and subjected to the first so-called waste firing. Firing is carried out before glazing at a temperature of 1250-1280 ° for earthenware and 900 ° for porcelain. The fired products are then glazed.

Glazes for earthenware are usually pre-fused low-melting mixtures of glass-forming materials, and for porcelain - a mass similar in composition to a shard of porcelain, but more fusible. Porcelain and earthenware products are most often glazed by dipping them in liquid glaze, that is, in the same way as pottery.

The second, poured, firing is used after glazing the products and is carried out at a temperature: for faience - about 1150 ° and for porcelain - about 1400 °. Due to the higher temperature of the second firing, the porcelain shard is sintered and, unlike earthenware, becomes not porous, but solid.

Both during the first and second firing, to prevent contamination with flue gases, the products are placed in special molds (capsules or boxes) made of refractory materials.

According to its external features, porcelain differs from earthenware in that it shines through in a thin layer and, when struck along the edge of the product, emits a long ringing sound, while earthenware does not shine through and, when struck along the edge, emits a low, rapidly decaying dull sound. Glaze on porcelain products is harder, its thermal stability is higher than that of earthenware products.

Tableware decoration. They decorate (paint) porcelain and earthenware with special, so-called ceramic, paints. The latter are most often finely ground alloys ground on turpentine, glycerin and other substances, similar in composition to colored fusible glasses, as well as special preparations of gold and silver.

The coloring of dishes can be underglaze and overglaze. In the first case, the products are painted before glazing after the first firing and the paints are fixed by the second (watered) firing. In the second case, finished products are painted and the applied paints are fixed by a special firing that follows the painting, the so-called muffle firing, carried out at a lower temperature than poured firing (about 800-900 °).

The coloring of porcelain products is most often overglaze, earthenware - overglaze and underglaze.

The limited use of underglaze coloring (especially in porcelain products) is explained by the fact that most ceramic paints do not withstand the high temperature of poured firing of products and lose their color at the same time.

The main types of decoration for porcelain and earthenware are as follows.

Ribbon, layering and tendril - colored stripes of various widths, applied with a brush to rotating products. A tendril is called a strip up to 1 mm wide, a layering - a strip up to 3 mm, a tape - a strip from 3 to 13 mm, and a strip up to 5 mm wide is called narrow, up to 9 mm - medium and above 9 mm - wide.

A stamp is a small one-color pattern, most often applied along the edge of products using a rubber stamp.

To digging and semi-covering - a continuous coating of all or part (semi-covering) of the product surface with paint. In this case, paint is applied using an airbrush, that is, a device that sprays paint, as well as a brush and a swab. In some cases, in order to get unpainted spots in the covering in the form of various patterns, paper is glued to the surface of the products before paint is applied, or the paint that has already been applied is removed (cleaned). In this case, the cover is called "cleaned".

Stencil - one-color or multi-color non-continuous patterns that are applied using an airbrush and stencils, that is, most often lead or copper plates, in which certain through patterns are cut. Such a plate is pressed against the surface of the products and the paint is applied by sawing it through the holes of the stencil.

The stencil is distinguished from other painting methods by the smooth, as if torn off edges of the drawing, the absence of brush strokes and the presence of gaps between the individual parts of the single-color drawing.

Printing - thin solid contour patterns that are first printed using metal rollers or plates on tissue paper, and then transferred from it to the surface of the product. In some cases, these contour patterns are additionally painted by hand. This printing is called "inked print". Patterns applied to products by printing are characterized by the presence of sharply delineated one-color contours.

Decalcomania (abbreviated as decal) are usually multi-color solid patterns applied to a product using multi-color decals (like children's ones, but made with ceramic paints).

Decal is distinguished from printing by the absence of a sharply delineated one-color contour and brush strokes.

Painting - hand-painted items with a brush or pen. Painted patterns are usually characterized by the presence of noticeable brush strokes and a thicker layer of paint.

Photoceramics - application of photographic images to products, most often portraits using transparencies, that is, photographic prints on glass. The photoceramics technique is quite complex.

Tableware decoration grouping by complexity. Patterns of varying complexity can be applied to each of the above methods; moreover, the general design can be done not in one, but in several ways. For example, a decal can be supplemented with a stamp, painting, layering, etc., a stencil - with a stamp, layering, etc. Therefore, each of the patterns applied to the dishes belongs to a certain group of complexity of coloring the product and the prices of products are made taking into account the number of the coloring group.

There are 20 such groups in porcelain, and 12 in earthenware. When establishing a group of complexity for coloring dishes, the method of applying the pattern (stencil, decal, print, etc.) is taken into account. Along with this, the nature of the pattern, the presence of additional cuts, and the type of paint applied are taken into account. So, they distinguish patterns with a bouquet, spreading, side and solid. Bouquet patterns have up to three moldings or patterns inclusive, spreading - from five and more, side - these are patterns located throughout the board, solid - patterns applied to the entire outer or inner surface of the product.

Additional cuts are variegation (partial painting of the product), cutting, touch-up and completion of the main drawing, glare - a relief smear with colorless paint, arabesque - a narrow side ornament, tsurovka - tracing a pattern along a ribbon with gold or silver.

So, for example, printing (on porcelain) with a bouquet without coloring and without additional decorations belongs to the fifth group, with a layer of paint - to the sixth, with a layer of gold - to the seventh. The same seal, but spread out, refers to the sixth (without layering), seventh (with layering paint) and eighth (with layering in gold) groups, and printing with coloring in two colors belongs to the eighth, ninth and tenth groups.

Assortment of porcelain and earthenware dishes

General grouping. Porcelain and earthenware dishes are subdivided according to purpose, types of products, styles, sizes, nature of decoration (cutting).

By design, porcelain and earthenware dishes are divided into tea (cups, saucers, teapots, etc.), coffee (coffee pots, coffee cups) and dining room (plates, dishes, bowls, etc.).

The types of dishes are very diverse. So, tea utensils include cups, saucers, mugs, glasses, teapots, sugar bowls, butter cans, creamers, rinsers, rusks, jugs, milk jugs, vases for cookies and sweets, fruits and jam, egg glasses. The assortment of tableware includes plates, dishes, broths, soup vases, gravy boats, salad bowls, saucers, herring dishes, mustard, salt shakers, pepper shakers, cheese boards.

The styles of dishes are currently designated by serial numbers: 1, 2, 5, 39, etc. The styles of porcelain cups are especially diverse (over 40 styles). Along with the designation of styles by numbers, in practice, there is also the designation of product styles with special terms, for example: a saucer with a basin, a rectangular salad bowl, a steam kettle, etc.

The dimensions of the dishes are indicated either by their capacity in cubic centimeters (for hollow dishes) or by diameter (for flat products).

Description of the assortment. Most types of tableware are made from both porcelain and earthenware. However, some products are made only from porcelain or, conversely, only from faience. So, for example, teapots are made only from porcelain, and bowls and swimmers are made only from faience.

A brief description of the main types of cookware is given below.

Cups are usually made from porcelain. They are subdivided according to styles and sizes. The styles of porcelain cups are usually designated by serial numbers (39, 51, 54, 58, etc.). The sizes of cups are indicated by their capacity, and sometimes by conventional names: appetizing (375-400 cm 3), semi-appetizing (275-300 cm 3), tea (200-220 cm 3), coffee (110-130 cm 3) and children's (60 cm 3). A significant number of cups are sold together with a saucer.

Porcelain and earthenware saucers are divided into tea, coffee and jam saucers. Tea saucers are of two styles: ordinary and a basin (in commercial practice, the latter are sometimes called cup holders).

Porcelain glasses are made of various shapes: conical - without a handle, cylindrical - without a handle, figured - with a handle and a saucer. Glasses of the latter type are also called goblets. The capacity of porcelain glasses of conical and cylindrical shape is 250 cm 3, figured shape is 375-400 cm 3.

Mugs are a cylindrical product with a handle. Porcelain mugs can be with a thick shard, with a capacity of 500 and 400 cm 3, and with a thin shard, with a capacity of 90 to 400 cm 3. Earthenware mugs are produced with a capacity of 200-400 cm 3.

Porcelain bowls (half cups) - tea utensils in the form of a round cup without a handle, on a low leg, with a capacity of 220-400 cm 3.

Teapots are made only of porcelain, they are distinguished by their styles and sizes. The styles of teapots are varied and are designated by numbers: 92 (the old name is "turnip"), 72 (the old name is "double"), 39, etc. Teapots that have the same styles as the cups are usually called set. The sizes of teapots are determined by their capacity. The capacity of service teapots is usually 600 cm 3, and the capacity of other teapots is from 250 to 1400 cm 3.

Porcelain coffee pots can be of various styles, with a capacity of 500-1400 cm 3. Coffee pots are usually sold as part of a coffee service.

Sugar bowls, like teapots, are produced only from porcelain, of different styles (according to the style of cups), with a capacity of 250, 350 and 500 cm 3.

Porcelain oilers by design are divided into oilers with a cap (on a plate) and oilers with a lid. The capacity of the oiler is 100 and 200 g. Faience oilers are usually produced with a lid, with a capacity of 250 g.

Porcelain and earthenware creamers are produced in various styles, with a capacity from 150 to 325 cm 3.

Porcelain rinsers can be of different styles (round, beaded, service), with a capacity from 500 to 1200 cm 3. Earthenware rinses are made in the form of a hemisphere, on a leg, their diameter is from 95 to 215 mm.

Porcelain rusks are usually produced flat (plate-like), 270 mm in diameter, as well as deep oblong, with a diameter of 310 to 335 mm. Earthenware rusks are made in the form of a wicker basket, on a leg, with a diameter of 200 mm.

Porcelain jugs can be of a wide variety of styles: No. 95, 96, 97, with a capacity of 750-1400 cm 3. Earthenware jugs are less diverse in shape, their capacity is 500-1500 cm 3.

Porcelain milk jugs differ from jugs in the absence of a lid and in a smaller variety of styles; their capacity is 500-1000 cm 3.

Vases for the intended purpose are for fruit and jam. Fruit vases are made from porcelain and earthenware, for jam - usually from porcelain. The dimensions of the vases are indicated by their upper diameter (for fruits - 240 mm, for jam - 120 mm).

Earthenware fruit bowls are round vases on a low stem, the diameter of their upper part is 130 and 230 mm.

Porcelain and earthenware plates are divided into deep and shallow ones according to their capacity. The styles of plates are distinguished by the shape of the edge (with an even edge, with a cut edge) and by the nature of the side surface (smooth and with a relief pattern along the side). Tray sizes are indicated by diameter. The most common sizes of porcelain deep plates are 200 mm (for children) and 240 mm (regular size) and small plates are 150 mm (pies), 175, 200 and 240 mm (snack bars). Earthenware deep plates come in sizes 200, 220, 240 and 255 mm, and shallow ones 175-180, 200, 220, 240 mm.

Porcelain and earthenware dishes are round and oval in shape (the so-called trays). Round dishes can be with a smooth and cut edge, smooth and faceted; oval dishes - various styles. The usual sizes of round dishes are 300, 325 and 350 mm, oval ones are 300, 350, 400 and 450 mm (in diameter).

Broths are round vessels with lids, in which there is a small hole for steam to escape, and with two handles. Broths are made from porcelain and earthenware. The capacity of the broths is from 0.6 to 2.4 liters.

Soup vases, or soup bowls, unlike broths, have an oval shape. In their lid, on one side, a cutout is made for a pouring spoon. The capacity of the soup vases is 2 and 3 liters.

Sauce-boats (sauce vases) differ from soup vases in capacity (0.8 l).

Porcelain and earthenware salad bowls are divided in shape into rectangular and service bowls. The sizes of salad bowls are determined by the capacity in cubic centimeters (from 120 to 1400 cm 3).

Porcelain saucers come in various shapes, without a pallet and with a pallet, with a capacity from 35 to 400 cm 3. Earthenware pots are usually made without a pallet, with a capacity of 400-450 cm 3.

Herring trays (herring trays) of various styles (oval, quadrangular, etc.) are made of porcelain and faience, with a diameter of 135 to 300 mm.

Bowls are made from faience. By their style, bowls are subdivided into ordinary and with edging (thickened edge), with a diameter of 190 to 265 mm.

Divers are earthenware products, similar in shape to semi-deep plates, their diameter is from 215 to 265 mm.

In addition to the listed products, the assortment of porcelain and earthenware dishes includes horseradish, mustard, pepper shakers, salt shakers, glasses for eggs, cheese boards, barrels for pickling, ashtrays, spittoon, etc.

Services and headsets. Sets and sets are sets of dishes of the same style, color and quality that have a specific purpose.

Services can be tea, coffee and dining rooms for 6 and 12 people, headsets - only tea sets for 6 and 12 people.

The tea set is made only of porcelain. It consists of 6 or 12 cups and saucers, a teapot, sugar bowl, creamer and gargle.

The coffee service includes 6 or 12 coffee cups with saucers, a coffee pot, a creamer, a sugar bowl and 6 or 12 small plates with a diameter of 175 mm.

A set is a more complete set of dishes. It completely includes a service for 6 or 12 people and additionally 6 or 12 small plates with a diameter of 175 mm, 6 or 12 saucers for jam, a butter dish, a rusk dish, a vase for fruit and a vase for jam.

Dinner sets for 6 people usually consist of 34 items, including 24 plates, and sets for 12 people have 66 items, including 48 plates. More complete sets are also possible, especially for 12 people.

Pricelist numbers for porcelain and earthenware... Each product included in the price list has its own number, consisting of two parts, separated by a dash. The first part of this number shows the serial number of the item according to the price list. So, for example, a porcelain round dish with a diameter of 300 mm is designated with the number 1, and with a diameter of 325 mm - with the number 2, a deep plate with a diameter of 240 mm - with the number 88, a tea cup with a capacity of 200-220 cm 3 - with the number 100, etc. numbers characterize the group of decoration (cutting) of the product.

Sorting porcelain and earthenware

In terms of quality, porcelain dishes are divided into the highest, 1st, 2nd and 3rd grades, and earthenware - into the 1st, 2nd and 3rd grades.

The grade of the dishes is determined by the defects found on it, taking into account the type (name) of the defect, its size, location on the product (on the front or back side), the size of the product, the number of defects of the same name and the total number of defects on the product.

Among the defects that can be on porcelain and earthenware include: insufficient whiteness of the shard; deformation (deviation from the correct shape), which is especially common in porcelain; front sight - dark spots on the shard, formed when the mass is contaminated with iron particles; pimples and blisters - swelling on the surface of the shard; blockage - particles of mass or capsules melted to the shard, in which the products are fired; cracks and cracks - glazed and unglazed; tsek - small cracks in the glaze; bald patches - places not covered with glaze; glaze incrustations - an uneven layer of glaze, most often on the edges of the products; incorrect mounting - skewed handles and spouts, incorrect selection of covers, etc.; fragility of paints - paint bouncing, washable paint.

The grade of the dishes is indicated by applying a stamp on the bottom of the products with indelible paint of various colors: red (for the highest grade of porcelain and 1st grade of faience), blue (for 1st grade of porcelain and 2nd grade of faience), green (for 2nd grade porcelain and 3rd grade earthenware) and brown or black (for 3rd grade porcelain).

Good-quality porcelain and earthenware dishes should be of the correct shape, stable, with evenly and firmly attached handles or legs, with a continuous even glaze. Fistulas (through holes), glaze chalk, scratching blockages, large bubbles, dry glaze exposing a shard, erasable paint, a through gap between the body and the lid of the product are not allowed in the dishes.

Majolica tableware

Majolica products are currently called products that, as a rule, have embossed decorations on the case and are covered with colored glaze.

By the nature of the shard, majolica products are usually similar to earthenware, however, in some cases, weakly colored pottery clays are also used in the production of majolica. Majolica products are molded mainly by casting in plaster molds.

By the nature of the decoration, there are majolica products without painting with colored glaze (one-color, two-color and four-color) and products painted with colored glazes or paint over a continuous one-color glaze.

The main types of majolica dishes are vases for fruits and sweets, beer mugs, jugs, oil cans, ashtrays, bread bins, salt shakers, egg glasses, cups and saucers, water cutlery, mugs with a lid “get drunk, don’t drown yourself”, etc.

The dimensions of these products are indicated by their capacity in cubic centimeters or liters, as well as by their diameter in millimeters.

Majolica dishes, like earthenware, are sorted into 1st, 2nd and 3rd grade.

Artistic and decorative items

Artistic and decorative items include flower vases, wall plates, various sculptural items, busts, bas-reliefs and some types of artistically decorated tableware.

Flower vases are made from porcelain, earthenware and majolica. Porcelain flower vases are especially varied. They can be of a wide variety of styles and sizes, they are mainly decorated with painting, often with the use of a continuous covering.

Wall plates are made of porcelain, with a diameter of 250 mm, they are most often decorated with paintings.

Sculptural items are very diverse in assortment, for example: accordion player, construction girl, Nakhimovites, girl with cat, trumpet hare, quartet, sitting bear cub, elephant, etc. The vast majority of these items are produced with painted glazed paints or gold.

Busts and bas-reliefs are unglazed or glazed porcelain items.

Artistic utensils include porcelain decanters for wine, stacks of decanters, mustard-plasters, mugs, oil cans, tea-casks, dining-dishes, etc. These utensils are decorated by hand with paints and gold.

Articles for products of this group are designated by serial numbers.

Sorting. In terms of quality, busts and bas-reliefs are of the highest and 1st grade. Vases and other porcelain products are divided into the highest, 1st, 2nd and 3rd grade, from faience and majolica - into 1st, 2nd and 3rd grade.

Marking, packaging, transportation and storage of ceramic products

Marking. Pottery is not subject to special marking. Porcelain, earthenware and majolica products are marked by applying a permanent stamp on the bottom of each product with an indication of the manufacturer and grade. In addition, a paper label is inserted (or pasted) into each pack indicating the price list and coloring group of the products packed in this pack.

Packing and transportation. Pottery is packed in straw, shavings, etc. They are transported in covered wagons without containers.

Porcelain and earthenware dishes are transported either without containers, in covered wagons (carload shipments), or in boxes or barrels. When transporting plates and saucers, as well as cups, if they are transported with saucers, are wrapped in paper through one piece, all other products - each separately. The cups are wrapped in a bag of 4-6 pieces together with saucers. Sets and sets are packed in sets. Porcelain and earthenware dishes are stacked in a wagon or box, basically in the same way as glassware, that is, in rows. Packing material is inserted between the rows.

Storage. The storage conditions for pottery are similar to those for glassware; most often, such dishes are stored together with glass.

For the rational use of the storage area and the convenience of dispensing, ceramic dishes are placed in several rows in height. So, plates, if they are wrapped through one in paper, are placed one on top of the other - up to 120 pieces; cups and saucers, if they are wrapped in bundles, - up to 10 rows in height with a reshaping of 4-5 sheets of thick paper every 2 rows; teapots - in 10 rows with each row shifting 2-3 layers of thick paper.

Basics of the production of ceramic products. The production of ceramic products includes the following main operations: preparation of mass, molding of products, drying, firing and decoration.

Materials used for ceramic production are usually subdivided into main and auxiliary ones. The main materials include materials used for the preparation of ceramic masses, glazes, ceramic paints; to auxiliary - materials used for the manufacture of plaster molds, capsules.

The main materials are divided into plastic, skinny, fluffy, glaze and ceramic paints.

Clays and kaolins are plastic materials. Clays and kaolins are formed as a result of the decay of rocks such as granite, gneiss, feldspar. Kaolins differ from clay in their purer chemical composition, less plasticity, and greater refractoriness.

Leaning materials are quartz and pure quartz sands, they help to reduce the plasticity of clays, reduce shrinkage and deformation of products during drying.

The fusions lower the melting and sintering temperature of clay materials, impart density, translucency, and mechanical strength to the ceramic shard; these include feldspar, pegmatite, chalk, limestone, dolomite.

Glaze-forming materials (glaze) are a thin glassy layer on the surface of ceramic products. It protects the shard from mechanical stress, improves its hygiene, and gives the surface of the product a better appearance. Glazes are transparent and opaque (dull), colorless or colored.

Ceramic paints are used to decorate porcelain, earthenware, majolica and other products. The basis of ceramic paints are metals and their oxides, which, when heated, form colored compounds on a shard of ceramic products with silicates, aluminates, borates and other substances. By the nature of their application, ceramic paints are divided into underglaze and overglaze paints.

Underglaze paints are applied to an unglazed nude shard, then the product is glazed and fired.

Overglaze - applied to a shard covered with glaze, and fixed with a special firing at a temperature of 600-850 ° C.

The preparation of the ceramic mass is carried out by sequential execution of a number of technological processes: purification of raw materials from harmful mineral inclusions, crushing, grinding, sifting through sieves, dosing and mixing.

Products are formed from plastic and liquid (slip) ceramic masses. Products of simple shapes (cups, plates) are molded from plastic mass with a moisture content of 24-26% in plaster molds using steel templates on automatic machines and semi-automatic machines.

The method of casting from a liquid mass - a slip with a moisture content of 30-35% into gypsum molds is indispensable in the production of ceramic products, where the complexity and variety of shapes exclude the use of other molding methods. Casting is carried out manually or automatically.

Drying helps to increase the strength of ceramic products formed from plastic mass or cast from slip. Drying is carried out in convection (conveyor, chamber and tunnel) and radiation dryers at a temperature of 70-90 ° C.

Roasting is the main technological process. As a result of complex physical and chemical transformations taking place at high temperatures, ceramic products acquire mechanical strength.

Firing is carried out in two steps. For porcelain products, the first (waste) firing takes place at a temperature of 900-950 ° C, and the second (poured) - at a temperature of 1320-1380 ° C. For earthenware products, the first firing is carried out at a temperature of 1240-1280 ° C, and the second - at a temperature of 1140-1180 ° C. Two types of furnaces are used: tunnel (continuous) and furnaces (batch).

Decorating products is the final stage in the production of porcelain and earthenware products, which consists in applying special cuts to linen (unpainted semi-finished product) by two methods: manual and semi-mechanized.

Antenna, cutoff, tape are continuous circular stripes (tendril 1 mm wide, cutoff - from 1 to 3 mm, tape - from 4 to 10 mm).

The stencil is applied with an airbrush using thin sheet or foil plates with cutouts, the contours of which correspond to the pattern being applied. It can be single-color or multi-color.

There are the following types of cover: solid - the whole product is covered with a uniform layer of paint; semi-covering - the product is covered with paint with a width of 20 mm and more, downward - the paint is applied with a weakening of tone to the bottom of the product; cover with cleaning - the pattern was cleaned along the solid cover; cover with cleaning and painting with paints and gold.

Printing is applied to the product from a printed print on paper, and a graphic monochromatic drawing is obtained, which is usually painted with one or more inks.

The stamp is the easiest way to decorate. The drawing is applied with a rubber stamp. More often the stamps are applied in gold.

Decalcomania (decal) takes the main place in the decoration of products. The drawing is transferred to the product using a decal made by a lithographic method. Currently, a sliding decal is used. A cellulose acetate film is applied to the backing paper, on which the pattern is printed. When wetted, the patterned film separates from the paper and remains on the product. In the process of muffle firing, the film burns out, and the paint is fused to the surface of the product.

Silk-screen printing is a promising way to decorate ceramic products. The pattern is printed through a silk mesh, on which a stencil is applied. The item to be decorated is brought under a silk net. A rubber roller with paint, passing through the mesh, pushes it into the cutouts of the stencil and thus the pattern is transferred to the product.

Painterly works are performed with a brush or pen by hand. Depending on the complexity, painting can be simple and highly artistic.

Photo ceramics reproduce portraits of famous people, city views on the product, it is especially effective in color.

Properties of ceramic products. The main properties of ceramic products are physical and chemical. The properties of ceramic products depend both on the composition of the masses used and on the technological features of their production.

The main properties are bulk density, whiteness, translucency, mechanical strength, hardness, porosity, thermal stability, speed of propagation of sound waves, chemical resistance.

The bulk density of porcelain is 2.25-2.4 g / cm 3, and earthenware 1.92-1.96 g / cm 3.

Whiteness is the ability of a material to reflect light falling on it. Whiteness is especially important for porcelain. Whiteness is determined visually by comparing the test sample with a standard or using a spectrophotometer.

Translucency is characteristic of porcelain, which is translucent even with a large thickness of the product, since it has a dense sintered shard. Earthenware products do not shine through because the shard is porous.

Mechanical strength is one of the most important properties on which the durability of the product depends. Specific mechanical strength, i.e. the ratio of the applied force to the unit of bottom thickness is determined by the method of free fall of a steel ball along the bottom of the product. It is higher in faience than in porcelain. On the other hand, the pendulum impact strength of earthenware is lower than that of porcelain.

The hardness of the glaze layer according to the Mohs mineralogical scale for porcelain is 6.5-7.5, and for earthenware - 5.5-6.5, the microhardness is determined by indentation of the diamond pyramid (according to Vickers). Porcelain glazes are hard, majolica glazes are soft, and earthenware is medium.

The porosity is determined by the method of water absorption, which; for porcelain it is 0.01-0.2%, and for faience - 9-12%.

Thermal resistance characterizes the product's ability to withstand sudden temperature changes. The thermal resistance of porcelain is higher than that of earthenware. So, in accordance with the current GOSTs, glaze for porcelain products must withstand temperature drops from 205 to 20 ° C, and for earthenware - from 145 to 20 ° C (for colorless glazes) and from 135 to 20 ° C (for colored glazes).

The speed of propagation of sound waves in porcelain products is 3-4 times higher than that of earthenware, therefore, when a wooden stick hits the edge, porcelain products emit a high sound, and earthenware - deaf.

The chemical resistance of glazes and ceramic paints used for household porcelain and earthenware products should be high, since when treated with weak acids and alkalis at ordinary temperatures or when heated to 60-65 ° C, they should not be destroyed.

Classification and assortment of ceramic products. All ceramic products are divided into rough and fine ceramics. Coarse pottery items have a heterogeneous shard structure, distinguishable by the naked eye; in addition, the shard has a natural color from yellow to brown tones.

Fine ceramics are characterized by a sintered fine-pored shard with a homogeneous, dense structure.

Rice. The main types of ceramic jewelry:

1 - layering; 2 - tape; 3 - stencil; 4 - stamp; 5 - solid cover; 6 - downward canopy; 7 - print; 8 - print with coloring; 9 - decal addiction; 10 and 11 - painting;

12 and 13 - photos of ceramics; 14 and 15 - cutting the relief

Fine ceramics include two groups:

1) products with a shard sintered in a fracture (hard porcelain, soft, bone and frit porcelain, fine stone products);

2) items with a porous shard (faience, majolica, semi-porcelain).

Hard porcelain is characterized by high mechanical strength, chemical and thermal resistance. Russian factories mainly produce porcelain from hard porcelain, which is prepared from a mass containing 50% clay substances, 25% feldspar and 25% quartz.

Soft porcelain has high translucency, but lower thermal and mechanical strength. The masses used in the production of soft porcelain contain 30% clay materials, 30-36% feldspar and 20-45% quartz. Soft porcelain is used in the manufacture of art products.

Bone china is made from a mass, which, in addition to the usual components, includes 20-60% bone ash. Bone china is characterized by high translucency, but at the same time low mechanical and thermal strength. It is used for making souvenir tableware.

Frit porcelain is similar in composition to glass, since it does not contain clay materials. Due to the insufficient hardness of the glaze and the laboriousness of the technological process, this type of porcelain is rarely used for the manufacture of dishes.

Fine stone products have a color depending on the natural properties of the clay (light gray, cream). These products have high thermal stability. They make chemical fine-stone utensils, as well as mugs, coffee and tea sets.

Faience has a white porous petiole, the water absorption of which ranges from 9-12%. Earthenware products are covered with low-melting glaze. The composition of the earthenware mass includes 65% of clay materials, 30% of quartz or quartz sand and 2-5% of feldspar.

Majolica is a kind of faience with high porosity. Majolica products are usually coated with colored glaze.

By its properties, semi-porcelain occupies an average position between porcelain and earthenware and is mainly used for the manufacture of sanitary ware. Semi-porcelain products are cheaper than porcelain and are of higher quality than earthenware.

Ceramic products are subdivided into tableware and decorative items. In turn, the utensils can be for table, tea and coffee purposes.

Porcelain products are divided by wall thickness into ordinary ones with a wall thickness of 2.5 (cup) - 4 mm and thin-walled 1.4 (cup) - 2.5 mm all the rest.

Depending on the size, ceramic products are divided into small and large.

According to the shape, the products are divided into hollow and flat.

Flat ones include saucers, dishes, plates, herring holders and others; to hollow - glasses, cups, mugs, bowls, teapots, coffee pots, sugar bowls, jugs and others.

Depending on the presence of the glaze layer, a distinction is made between glazed and unglazed (biscuit) porcelain.

According to the completeness of the product, there are piece and complete (services, headsets, sets). A feature of the products included in the kit is the unity of decorative design, design and shape.

Porcelain. According to the purpose, the assortment of household porcelain products is divided into dining room, tea, household utensils and others.

Artistic and decorative items are especially highlighted.

Porcelain tableware is represented by a wide variety of products, both in terms of names, and in styles and sizes.

Dishes are produced in round and oval sizes of 300, 350, 400 and 450 mm.

Vases for soup or compote are made with lids of different styles with a capacity of 2000-3500 cm 3.

Gravy makers come without a pallet and with a pallet (on a plate) with a capacity of 80 to 400 cm 3.

Salad bowls are characterized by different styles (round, oval, quadrangular) and a capacity of 1200-1400 cm 3, rectangular have a capacity of 120 to 1000 cm 3.

Herringbeds are produced in lengths of 135 and 250-270 mm.

Plates are the main type of tableware. They are deep and shallow, for adults and children. Deep plates are produced with a diameter of 240 and 200 mm and shallow 240 mm (support for a deep plate 240 mm), 200 mm (for main courses), 175 mm (snack bar) and 158 mm (pastry). Children's plates deep and shallow with a diameter of 178 mm are included in children's sets. In addition to the listed products, this group includes products for spices - mustard, salt shakers, pepper shakers and horseradish.

Tea and coffee utensils are very diverse in styles, sizes and decor. Cups and saucers occupy the main place in the assortment of this group. Tea cups differ from coffee cups in capacity. So, coffee cups have a capacity of 60, 85 and 100-130 cm 3. The capacity of tea cups is 200-250 cm 3 (ordinary), 260-275 cm 3 (medium-sized), 300-350 cm 3 (large) and 400 and 500 cm 3 (gift).

Teapots distinguish between teapots (for brewing tea) with a capacity of 250, 350-375, -450, 500-700, 735-800 cm 3 and topping up (for boiling water) with a capacity of 1000-1250, 1400 and 3000 cm 3.

Glasses are produced in different styles with saucers with a capacity of 375-400, 500 and 600 cm 3.

Coffee pots are made in different styles with a capacity of 500, 750, 1000-1250, 1400 cm 3.

Mugs are made with a handle and without a handle, with a thickened shard and special resort flat mugs with a hole in the handle. The capacity of the mugs ranges from 90 to 500 cm 3.

Bowls are conical in shape, without handles with a capacity of 140-150, 220-250, 350-400 cm 3.

The group of tea and coffee utensils also includes vases for fruit and jam on a leg.

Other products are cheesecakes, napkin holders, etc.

Complete utensils are produced in the form of sets, sets, sets; it is characterized by the unity of form (style) and cutting.

Services and sets for their intended purpose are canteens, tea and coffee rooms for 6 and 12 persons. The set includes more items than a set for the same purpose.

Artistic and decorative items occupy a significant place in the group of porcelain items. The range of artistic and decorative products includes sculpture (figurines of people, animals, birds, fish, etc.), busts, wall bas-reliefs, flower vases, various products (powder boxes, ashtrays, pencil holders, wall dishes and plates, wine decanters , commemorative medals, etc.).

Applied art products are characterized by a combination of utilitarian properties with high aesthetic ones. These products are varied in shape, they are more carefully trimmed and decorated (usually by painting).

Faience products. The range of earthenware products is simpler and less diverse than similar porcelain products. Flat products (plates, bowls, herring holders, etc.) occupy a significant share. The assortment of earthenware products does not include tea cups, teapots, coffee pots. Basically, the assortment of earthenware is represented by tableware. Earthenware dishes consist of piece and complete products. The complete products include table sets, sets of plates (different sizes and children's sets).

Artistic and decorative items occupy an insignificant place in the range of earthenware products, mainly sculpture, flower vases and ashtrays of various styles.

Majolica and pottery. The assortment of majolica products includes tableware and decorative items.

Majolica products are characterized by cutting with various colored glazes (majolica glaze) and underglaze paints.

The assortment of majolica products is represented by both piece and complete tableware. They produce mugs, oil cans, coffee pots, rusks, ashtrays, glasses for eggs, cheese dishes, salad bowls, mead bowls; the range of products is especially widespread for fruit, pancakes, salad, eggs, water, jam, compote, tea, spices, as well as coffee and children's appliances.

Artistic and decorative items are flower vases, wall dishes and plates, ashtrays, sculptures and others.

Pottery belongs to rough ceramics. The main raw material is low-melting clay of medium plasticity. These products are molded on a potter's wheel or in plaster molds. After drying and glazing, they are fired in forges at a temperature of 900-1000 ° C.

The assortment of pottery consists of pots, pots, bowls, jugs, butter cans, rusks, vessels for sour cream and butter, flower pots. The following artistic and decorative items are produced from pottery: flower vases, flower pots, wall dishes, sculptures, toys, etc.

Evaluation of the quality of ceramic products. Ceramic products must be durable, easy to use, and have a beautiful appearance. They are made in accordance with the samples approved in accordance with the established procedure. When evaluating the quality of ceramic products, attention is paid to the quality indicators of the shard, glaze and decoration. Depending on the appearance, physical and technical indicators, nature, size and number of defects, the dishes are divided into 1 and 2 grades according to the current state standards.

Whiteness, thermal stability, water absorption, acid resistance are determined according to the methods set forth in GOSTs.

The whiteness of porcelain items for grade 1 must be at least 64%, for grade 2 - 58%. For earthenware products, whiteness is not regulated.

Translucency is characteristic only for porcelain products, which are translucent in layers up to 2.5 mm thick. Porcelain and earthenware plates and saucers are considered mechanically strong, which, when stored in piles for five days (the first 120 pieces, and the second 100 and 150 pieces), do not collapse.

The presence of defects is established by external examination of the product. All the variety of defects found on ceramic products are divided into shard and glaze defects and decoration defects.

Sharp and glaze defects. The deformation of the product is expressed in its curvature. This defect occurs as a result of the directional conduct of the drying and firing processes. Especially typical for flat products. The deformation is measured using a stepped template in millimeters and has GOST tolerances for the main types of products.

Potholes and cracks on the product are formed during production, transportation and storage.

Glazed one-sided cracks represent blind cuttings of a shard.

The glaze spillage on the shards should be smooth and even. Minor inconsistencies are allowed. Small dispersed pricks that do not violate the presentation of the product are allowed. Dullness of glaze in grade 1 is not allowed.

Balloons and glaze build-up appear as non-glazed spots. On the front side of porcelain items in grade 1, and on earthenware items in grade 1 and 2 are not allowed.

Dry glaze and flying edge are found on earthenware products. Dry glaze results from insufficient thickness of the glaze layer on the product. The flying edge sharply reduces the hygienic properties of the product; it is characterized by glaze rebound along its edges in grade 1 is not allowed.

The hairline and hair are cracks in the glaze layer. Products with these defects are rejected.

Clogging appears on the products as a result of chamotte chipping from the capsules. It can be underglaze, as well as overglaze, which can be sanded.

The front sight appears as dark dots on the product. This defect appears due to the ingress of iron oxides into the ceramic mass.

Traces from runners and combs are characteristic only for earthenware products and are allowed on the back side sanded or sanded.

Incorrect mounting of product parts is their asymmetrical arrangement, deviation of attached parts (spouts, handles) from the vertical and horizontal planes.

Undermining of attached parts is allowed if it is hairy and blind and does not violate the mechanical strength of the product. However, undermining the spouts of teapots is not allowed.

Decoration defects. Burning or underburning of paints is formed when the muffle firing is disturbed. The paint should not rub off.

Assembling the decal is allowed if it does not violate the pattern.

Overglaze paint blots on the front side of the product in grade 1 are not allowed.

Peeling paint turns the product into a scrap.

According to GOST, the number of permissible defects should not exceed 3 for porcelain items for grade 1, and 6 for grade 2; for earthenware products, respectively - 3 and 6.

Ceramic goods labeling, packaging, transportation and storage. Each porcelain and earthenware product is marked with a trademark, which is applied to the center of the bottom of the product with ceramic paint and fixed by firing. The trademark must be clear.

When packing dishes, consumer containers are used (boxes made of cardboard, paper and combined materials); packs of cardboard, paper and combined materials and paper and combined materials packages, auxiliary materials (wrapping and interleaving paper, corrugated cardboard, heat shrinkable materials, polyethylene film, polystyrene, wood chips, etc.); transport containers (wooden boxes and corrugated cardboard boxes).

Cups and saucers are placed in the following way: the cup is placed upside down on a saucer on the front side, previously folded with paper, and wrapped in paper. Then a stack is formed containing from two to twelve products, which is also wrapped in paper. Forming of feet, made up separately of cups and saucers, is acceptable.

Flat products are wrapped in paper through one product, and then in a bag of 25-40 pieces. The enlarged package is tied with twine or sealed with paper tape and a label is attached indicating the manufacturing plant and its address, product name; the number of products in the package, grade, packing date, packer number and GOST or TU number.

When packing packages of services, sets, headsets, products of the same type and one decorative design are stacked: each item is wrapped in paper. Then the dishes are placed in consumer and shipping containers. Souvenir and gift items are placed in corrugated cardboard boxes, on which artistically designed labels are glued.

Dishes are transported by all means of transport. Basically, dishes are transported in railway wagons and containers, the floor of which is lined with wood chips in a uniform and dense layer. Rows of packages are also laid with shavings. On containers and railway wagons, the manufacturer must make the inscription "Caution glass".

Dishes sent to the Arctic, the Far North and remote areas are packed in accordance with special specifications.

Porcelain and earthenware products are stored in closed dry rooms on racks. In this case, heavier products are placed on the lower racks, light ones - on the upper ones. Plates can be stored in stacks (porcelain - 120, and earthenware - 100).