porcelain vase
Porcelain tableware has always been highly valued and can last for decades, and the presence of porcelain dishes has always been considered a sign of wealth. What is porcelain made from? What types of porcelain are there? How is chinaware made?
Composition of porcelain
Porcelain is usually obtained by high-temperature firing of a coarse mixture of kaolin, quartz, feldspar and plastic clay (mainly kaolin, with inclusions of chromophore ions).
Depending on the composition, porcelain is divided into hard and soft. The hardness of finished porcelain is the same, and they got such names because more liquid phase is formed during the manufacture of soft porcelain.
The composition of hard porcelain includes:
- 47-66% kaolin,
- 25% quartz,
- 25% feldspar.
Hard porcelain is richer in kaolin (alumina) and poorer in fluxes. To obtain the necessary translucency and density, it requires a higher firing temperature from 1400 °C to 1460 °C.
The hardest porcelain is bone china, which contains up to 50% bone ash, as well as kaolin, quartz, etc., and which is distinguished by its special whiteness, thin-walledness and translucency.
Hard porcelain is usually used in technology (electrical insulators) and in everyday life, more often as dishes.
Soft porcelain consists of:
- 25-40% kaolin,
- 45% quartz,
- 30% feldspar.
The firing temperature usually does not exceed 1300-1350 °C.
Soft porcelain is used primarily for the manufacture of artistic products.
Basically, porcelain is glazed. White, matte, unglazed porcelain is called biscuit.
Porcelain is painted in two ways:
- underglaze painting,
- overglaze painting.
Porcelain painting
From the names it is clear how painting is applied to porcelain. When painting underglaze porcelain, paints are applied to unglazed porcelain. Then the porcelain product is covered with transparent glaze and gently fired at temperatures up to 1350 degrees.
Overglaze painting is applied to glazed unpainted white porcelain and then fired in a muffle furnace at a temperature of 780 to 850 degrees.
During firing, the paint is fused into the glaze, leaving behind a thin layer of glaze. Paints after a good firing are shiny (except for special matt paints used only for decorative purposes), do not have any roughness and subsequently better withstand the mechanical and chemical effects of acidic foods and alcohol.
The color palette of overglaze painting is richer than that of underglaze painting.
Now, using chinaware in everyday life, you will know what it is made of.
Visited the enterprise "Art-Modern ceramics" engaged in porcelain products. It is very pleasant at the present time to see such small (and the company employs about 50 people) production with almost manual labor, where the products remember the warmth of the hands that made them. Due to the peculiarities of production (technology, volume), there are no multi-series products, in-line production.
Everything is produced in small batches and is born within the walls of a small building, divided into different rooms - stages of production. Unfortunately, it is difficult to shoot a report and memorize explanations, so I will only talk about those moments that made an impression on me.
1. In addition to traditional tableware, the company has many corporate orders. Police, traffic police, Russian Railways and others. For example, here is a commemorative contraption for the Mil Design Bureau.
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3. Order for the police - Uncle Styopa.
4. And this is a vase for Russian Railways. And it's all hand painted. The only thing is that the images to the left and right of the locomotive were made using decals.
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6. Various products.
7. Here, and this is the casting of the workpiece. Gypsum mold into which porcelain mortar is poured. The first question was, how are cavities made inside? It turned out that everything is simple. The gypsum form forms only the appearance, and inside everything is poured with a solution.
Then the gypsum begins to take water from the porcelain, and the outer layer of the solution hardens. The more the workpiece costs, the thicker the wall is formed.
8. And then the unnecessary solution is poured out (it goes for reuse) and a thin-walled contraption is obtained.
9. Then the blank is brought to mind, polished, burrs removed and prepared for painting.
10. These are blanks for teapots for KB Mil.
11. Complex things are assembled from several parts.
12. Seals.
13. And these are pasted decals before re-annealing. After the oven, the paint from the decal fuses into the glaze and becomes an integral part.
14. Coloring hares.
15. The second discovery for me was that the cobalt paint is black. And only after the stove it turns blue.
16. Painting.
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18. And this is preparing hares for 2011, which will be the year of the rabbit.
19. Mega gate valve.
20. Glaze coating.
21. Clone army.
22. Adorable hares.
23. Painting hares.
24. Model and plaster mold.
25. Kilns for roasting.
26. After firing.
27. All ovens except one are electric. But one works on liquefied gas. One such dressing is enough for one firing.
28. Workshop for the production of plaster molds.
29. Box workshop.
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31. Small casting workshop.
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33. Final fine-tuning.
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35. The plaster figurine of Terkin was created in 1939 (I could confuse the date, since the poem was published only in 41, although work on it began just in 39). For a long time she fell into disrepair. The workshop specialists restored the plaster figurine, made the mold and now there is an opportunity to admire the porcelain Terkin.
Porcelain is also distinguished depending on the composition of the porcelain mass on soft And solid. Soft porcelain is different solid not by hardness, but by the fact that when firing soft porcelain, more liquid phase is formed than when firing hard porcelain, and therefore the risk of deformation of the workpiece during firing is higher.
The term "porcelain" in English-language literature is often applied to technical ceramics: zircon, aluminous, lithium, boron-calcium etc. porcelain, which reflects the high density of the corresponding special ceramic material.
soft porcelain
Porcelain painting
Porcelain is painted in two ways: underglaze painting and overglaze painting.
When painting underglaze porcelain, paints are applied to unglazed porcelain. Then the porcelain product is covered with transparent glaze and fired at a high temperature of up to 1350 degrees.
The palette of colors of overglaze painting is richer, overglaze painting is applied on glazed linen (a professional term for unpainted white porcelain) and then fired in a muffle furnace at a temperature of 780 to 850 degrees.
During firing, the paint is fused into the glaze, leaving behind a thin layer of glaze. Paints after a good firing are shiny (except for special matt paints used only for decorative purposes), do not have any roughness and subsequently better withstand the mechanical and chemical effects of acidic foods and alcohol.
Among the paints for painting porcelain, a group of paints prepared using noble metals stands out. The most common paints using gold, platinum and silver paint (or argentine).
Gold paints with a lower percentage of gold content (10-12%) are fired at a temperature of 720 to 760 degrees (bone china is fired at a lower temperature than hard - "real" - porcelain). These paints are more decorative, and the products decorated with them cannot be subjected to mechanical stress (wash with abrasives and in a dishwasher.)
Gold, silver chandeliers, polishing polishing and powdered gold and silver (50-90%) are fired at a higher temperature along with paints. The polishing polish and powdered gold after firing have a matte appearance and are painted with an agate pencil (the pattern is applied approximately like a simple pencil on paper, only you cannot make a mistake with shading the pattern, since this cannot be corrected later. The master in this case must be very highly qualified) Combination matt and shiny gold after polishing creates an additional decorative effect on porcelain. Chandeliers and powdered gold paints are more stable on porcelain than 10-12% gloss. However, in the entire history of the creation of porcelain and its technologies, nothing better and cheaper than decorating porcelain with gloss has been invented.
Professional overglaze painting is carried out on gum turpentine and turpentine oil. Paints are pre-soaked on the palette for a day or more. After work, they are thoroughly rubbed with the addition of turpentine oil. Turpentine in jars should be dry, slightly greasy (turpentine gradually changes from one state to another). The oil should also be more fluid and thicker. For work, a piece of soaked paint is taken, oil, turpentine are added - and the mixture is diluted to the consistency of thick sour cream. For brushstroke painting with a brush, the paint is diluted a little thicker, for pen painting - a little thinner.
It is important that the paint does not spread from the pen or brush. Underglaze paint is diluted on water, sugar with the addition of a small amount of glycerin.
Story
Porcelain was first obtained in 620 in China. The method of its manufacture was kept secret for a long time, and only in 1708 the Saxon experimenters Tschirnhaus and Böttger managed to obtain European porcelain (Meissen).
Attempts to discover the secret of oriental porcelain continued for almost two centuries in Italy, France and England. However, the result was materials that vaguely resembled porcelain and were closer to glass.
Johann Friedrich Böttger (1682-1719) began to conduct experiments on the creation of porcelain, which in 1707/1708 led to the creation of "rothes Porcelain" (red porcelain) - fine ceramics, jasper porcelain.
However, real porcelain had yet to be discovered. Chemistry as a science in its modern sense did not yet exist. Neither in China or Japan, nor in Europe, raw materials for the production of ceramics could yet be determined in terms of chemical composition. The same was true for the technology used. The process of porcelain production is carefully documented in the travel notes of missionaries and merchants, but the technological processes used could not be deduced from these reports. Known, for example, are the notes of the Jesuit priest François Xavier d "Antrekol (English) Russian, containing the secret of Chinese porcelain production technology, made by him in 1712, but became known to the general public only in 1735.
Understanding the basic principle underlying the porcelain production process, namely the need to fire a mixture of different types of soil - those that fuse easily and those that fuse more difficult - arose as a result of long systematic experiments based on experience and knowledge of geological, metallurgical and "alchemical-chemical" relationships. It is believed that the white porcelain experiments went hand in hand with the rothes porcelain because only two years later, in 1709 or 1710, white porcelain was more or less ready for production.
Introduction
Porcelain is the main representative of fine ceramics. The characteristic features of porcelain are white with a bluish tint, low porosity and high strength, thermal and chemical resistance and natural decorative effect. Its features are determined by the chemical composition and structure of the crock, which depend on the purpose of the product, the conditions of their operation and the requirements for them.
Porcelain has high mechanical strength, chemical and thermal resistance, electrical insulating properties and is used for the manufacture of high-quality tableware, artistic, decorative and sanitary ware, electrical and radio engineering parts, corrosion-resistant chemical technology apparatuses, low-frequency insulators, etc.
Porcelain is usually obtained by high-temperature firing of a fine mixture of kaolin, feldspar, quartz and plastic clay (such porcelain is called feldspar). The term "porcelain" in the English literature is often applied to technical ceramics: zircon, alumina, lithium, calcium boron and other porcelain, which reflects the high density of the corresponding special ceramic material.
Porcelain is also distinguished depending on the composition of the porcelain mass into soft and hard. Soft porcelain differs from hard porcelain not in hardness, but in the fact that when firing soft porcelain, more liquid phase is formed than when firing hard porcelain, and therefore the risk of deformation of the workpiece during firing is higher.
Hard porcelain is richer in alumina and poorer in fluxes. To obtain the necessary translucency and density, it requires a higher firing temperature (up to 1450 °C). Soft porcelain is more diverse in chemical composition. The firing temperature reaches 1300 °C. Soft porcelain is used mainly for the manufacture of art products, and hard porcelain is usually used in technology (electrical insulators) and in everyday life (dishes).
One of the types of soft porcelain is bone china, which includes up to 50% bone ash, as well as quartz, kaolin, etc., and which is distinguished by its special whiteness, thinness and translucency.
Porcelain is usually glazed. White, matte, unglazed porcelain is called biscuit. In the era of Classicism, biscuits were used as inserts in furniture products.
PRODUCTION PROCESS
Preparation of raw materials
The composition of the ceramic mass and the method of its preparation are determined based on the purpose of the product, its shape and type of raw material. The purpose of the preparation of raw materials is the destruction of the natural structure of materials to the smallest particles in order to obtain a homogeneous mass and accelerate the interaction of particles in the process of porcelain formation. It is carried out mainly by a plastic method, which provides a uniform composition of the mass.
Plastic materials (clay, kaolin) are dissolved in water in paddle mixers. The resulting mass in the form of a suspension is passed through a sieve (3600 - 4900 holes per 1 cm2) and an electromagnet to remove large inclusions and ferruginous impurities.
Weakening materials and fluxes are sorted, freed from foreign and harmful impurities. Quartz, feldspar, pegmatite and other components are fired at a temperature of 900-1000°C. In this case, quartz undergoes polyform changes, as a result of which it cracks. This, firstly, makes it easier to grind, and secondly, it makes it possible to remove pieces contaminated with ferruginous impurities, since during firing, quartz with impurities of ferruginous compounds acquires a yellow-brown color.
Stony materials, including porcelain batt, are washed, subjected to crushing and coarse grinding on runners, and then sieved. Fine grinding is carried out in ball mills with porcelain or uralite balls. To intensify grinding, a surface-active additive is introduced into the mill - sulfite-alcohol bard (from 0.5 to 1%), which, filling microcracks, has a kind of wedging effect. Grinding is carried out to a residue of 1-2% on a sieve with 10,000 holes per 1 cm2.
Plastic and emaciated materials, fluxes and porcelain batt are thoroughly mixed in a propeller-type mixer. A homogeneous mass is passed through a sieve and an electromagnet and dehydrated in special filter presses or vacuum filters. The resulting plastic mass with a moisture content of 23-25% is sent for two weeks for aging in a room with high humidity. During aging, oxidative and microbiological processes, hydrolysis of feldspar and the formation of silicic acid occur, which contributes to the loosening of the mass, further destruction of the natural structure of materials and an increase in the plastic properties of the mass. After aging, the mass is processed on mass grinders and vacuum presses to remove air inclusions, as well as plasticity and other physical and mechanical properties necessary for the formation of products.
Types of porcelain
Depending on the composition of the porcelain mass and glaze, hard and soft porcelain are distinguished. Some intermediate type is represented by the so-called bone china.
hard porcelain contains mainly two starting materials: kaolin and feldspar (most often in combination with white mica; melts relatively easily). Quartz or sand is added to these basic substances. The properties of porcelain depend on the proportion of two main substances: the more kaolin its mass contains, the more difficult it is to melt and the harder it is. This mixture is ground, kneaded, milled and then dried to the extent of a pasty state capable of taking shape. A plastic mass appears, which can either be cast in molds or turned on a potter's wheel. Finished objects are fired twice: first without glaze at a temperature of 600-800 degrees C, then with glaze - at 1500 0 C. Feldspar or pegmatite are used as fluxes. Cover hard porcelain with hard glaze. Thin varieties are covered with lime-free spar glaze, so the products are matte, milky-cream in color. But simpler varieties are covered with a completely transparent lime glaze. Glaze and porcelain mass consist of the same substances, only in different proportions. Thanks to this, they are connected and the glaze can no longer be beaten off or peeled off.
Hard porcelain is characterized by strength, strong resistance to heat and acids, impermeability, transparency, conchoidal fracture and, finally, a clear bell sound. Invented in Europe, in 1708 in Meissen by Johann Friedrich Bötger.
soft porcelain , also called art or frit, consists mainly of mixtures of vitreous substances, the so-called frits, containing sand or flint, saltpeter, sea salt, soda, alum and crushed alabaster. After a certain melting time, marl containing gypsum and clay is added to this mass. In principle, this means that we are talking about a fused vitreous substance with an addition of clay. All this mass is ground and filtered, bringing to a plastic state. The molded object is fired at 1100-1500°C, becoming dry and non-porous. The glaze is predominantly made of glass, that is, of a fusible substance rich in lead oxide and containing, in addition, sand, soda, potash and lime. Already glazed products are subjected to secondary firing at 1050-1100°C, when the glaze is combined with the shard. Compared to hard, soft porcelain is more transparent, the white color is even more delicate, sometimes almost creamy, but the heat resistance of this porcelain is lower. The fracture is straight, and the unglazed part is granular in the fracture. The initial European porcelain was mostly soft, which is exemplified by the fine and highly valued products of the Sevres. It was invented in the XVl century in Florence (Medici porcelain).
Bone china represents a well-known compromise between hard and soft porcelain. Its composition was discovered in England and its production began there around 1750. In addition to kaolin and feldspar, it contains lime phosphate from burnt bone, which makes smelting easier. Bone china is fired at 1100-1500°C. So, we are talking essentially about hard porcelain, but one that is made softer by mixing burnt bone.
Its glaze is basically the same as on soft porcelain, but contains, in addition to lead oxide, a certain amount of borax for better connection with the shard. With appropriate incandescent heat, this glaze melts and is firmly connected to the shard. According to its properties, bone china occupies an intermediate position between hard and soft porcelain. It is harder and harder than soft porcelain and less permeable, but it has a rather soft glaze in common. Its color is not as white as that of hard porcelain, but whiter than that of soft porcelain. Bone china was first used in 1748 at Bow by Thomas Fry.
From the above, we can conclude; that the main ones for the manufacture of porcelain, there are three types that differ in composition, firing temperature and are used for different types of products. Also, for each type, its own glaze is made.
PORCELAIN PRODUCTION TECHNOLOGY
. Porcelain production
The production process for the manufacture of ceramic products consists of several stages:
preparation of raw materials;
mass preparation;
product formation, firing;
glazing and decor.
The preparation of raw materials consists in cleaning the source materials from impurities, thorough grinding, sifting, drying, etc. The preparation of the mass consists of mixing the raw materials in certain proportions and mixing the mixture with water until a homogeneous liquid porcelain mass is obtained. The mass is passed through a sieve, cleaned (with an electromagnet) from iron impurities and dehydrated (on filter presses or vacuum presses) to obtain a forming dough.
free molding on the potter's wheel;
plastic molding by hand imprint in the mold;
plastic molding in a rotating plaster mold using a molding template or roller;
· Formation of the vessel by the method of circular molding. Molding by slip casting in plaster molds;
production of ceramic products by a combination of several molding methods.
The method of free molding of ceramic products on the potter's wheel consists in the mechanical action of the potter's hands on the clay blank in the form of plastic dough. First, the master prepares the potter's wheel for work. The first stage is the primary processing of the workpiece. Then the internal cavity of the product, the edges of the workpiece, and again the internal cavity are formed. After that, the master pulls the workpiece to the desired height. During all these operations, he rotates the potter's wheel with his foot or with a drive mechanism. The process ends with finishing the outer surfaces, trimming the bottom, and drying. During drying, the product can be decorated with stucco details, seals, stamped moldings.
Plastic molding by hand imprint is carried out using plaster molds. Forms can be open and detachable; open ones are used for molding flat products; detachable - in the development of products on three-dimensional models of complex shapes.
Plastic molding in a rotating plaster mold using a template or roller is as follows. The form, which opens into two halves, is installed in the assembled form in the rotating bowl of the machine. A lump of clay is fed into the inner cavity of the mold, calculated on the volume of the manufactured product. A forming template is lowered into the mold cavity, which evenly distributes the clay mass in the inner side of the mold, after which it is lifted and removed from the mold. Then the form with the product is removed from the setting machine, dried, opened, the product is removed and further processing is continued (attachment of parts - spouts, handles, covers and other additional mounts).
Molding by the method of slip casting into plaster molds is based on the property of gypsum to absorb moisture, and the ability of clay to transfer from a liquid slip to a plastic dough state when the humidity decreases. Products are formed as follows. The slurry is poured into the inner cavity of the gypsum mold, as a result of which moisture is redistributed between the slurry, which releases moisture, and the gypsum mold, which absorbs this moisture. After redistribution of moisture on the inner working surface of the gypsum mold, a layer of clay mass is formed from the slip, turning into a state of plastic dough. When the form has "gained" the specified thickness of the layer of clay, the slip is poured out of the inner cavity of the mold, and the layer of clay on the inner surface of the mold remains. This layer of thickened slurry is a molded hollow pottery raw material. As it dries, the raw material in the form, decreasing, separates from its walls.
The manufacture of ceramic products by a combination of several molding methods makes it possible to obtain products of complex shape. The combination of the plastic molding method in a rotating plaster mold with a metal template or roller with slip casting and mounting of attachments is widespread in the production of teapots, sugar bowls, cups, decanters, bowls and other porcelain and earthenware products consisting of a body and individual parts. After molding, the products are dried in air and fired.
What to bring from St. Petersburg - crumpets, smelt? For example, a piece of the curb is still possible (they are sold, so you don’t even have to pick it out as a keepsake), but the best thing is the product of the Imperial Porcelain Factory. Perhaps every real Petersburger has a cup with the famous cobalt mesh at home. Or a figurine or something special.
Not so long ago, I was able to visit the Imperial Porcelain Factory and see how famous products are created and, of course, that very recognizable cobalt mesh.
Reference: The plant was founded in 1744 (20 years earlier than the Hermitage!) by decree of Empress Elizabeth.
The works of the Imperial Porcelain Factory are included in the treasury of world porcelain and are represented in the collections of the best museums in the world.2
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This is how the Cobalt mesh looks like before firing it is black:
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This year, the plant celebrates the 70th anniversary of its creation and the 65th anniversary of the launch of its brand name - the Cobalt Net service.
And at the world exhibition in Brussels, the service received a gold medal for the pattern and shape “Tulip”.
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The author of the service is the artist Anna Yatskevich, she also came up with the official logo of the Lomonosov Leningrad Porcelain Factory - LFZ. Petersburger, born in 1904, Anna Yatskevich remained in Leningrad throughout the blockade, worked, in 1944 - on the occasion of the 200th anniversary of the Porcelain Factory - she was awarded the Order of the Red Star.
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Anna Yatskevich decided to try cobalt pencils when painting - they have a cobalt core instead of graphite. At first, cobalt stripes alternated with stripes made in red paint.
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There are many theories about the origin of this traditional decor, but even experts do not know the exact answer.
Perhaps it was inspired by Elizaveta Petrovna's "Own Service" or a Viennese service with a so-called trellis net stored in the factory museum. Or memories of the cross beams of the besieged searchlights bursting into the sky and the cross-sealed windows of the besieged city.
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Then the products are sent to the oven and the mesh turns blue:
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The artist has been working on such a dish for about two weeks:
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Porcelain is usually obtained by high-temperature firing of a coarse mixture of kaolin, quartz, feldspar and plastic clay. But each porcelain is unique and no one discloses its exact recipe.
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Porcelain is divided into soft and hard. Soft porcelain differs from hard porcelain not in hardness, but in the fact that when firing soft porcelain, more liquid phase is formed than when firing hard porcelain, and therefore the risk of deformation of the workpiece during firing is higher.
The hardest porcelain is bone china.
Bone china is particularly refined, thin-walled and translucent.
Porcelain is usually covered with icing, and uncovered is called a biscuit.
They all look different
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This is a biscuit (appetizing such names for porcelain are biscuit, icing)
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Waste production:
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Liquid porcelain mass, slip, is poured into a plaster mold:
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Complex products are made from several parts and fastened with a thicker porcelain mass:
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Like this:
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Details:
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Defective figurines also look cool, and you want to take them away (it’s still a marriage, right?), but employees are forbidden to take something away, then it’s all used as raw materials for new products
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The plaster mold is assembled from two parts, so that later it can be disassembled and the product removed.
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After some time, the figure is removed:
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Figurines based on Shemyakin's sketches:
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And this inscription, as Igor said, must be broadcast in the registry office:
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Part molds:
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A copy from the series "Peoples of the Russian Empire":
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And this is frosting. Before lowering the product into it, it is necessary to mix until a homogeneous state:
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And then the product is dipped there, just like that, without gloves:
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Even containers with paints with the famous decor:
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Porcelain is painted in two ways: underglaze painting and overglaze painting.When painting underglaze porcelain, paints are applied to unglazed porcelain.
Then the porcelain product is covered with transparent glaze and fired at a high temperature of up to 1350 degrees.
The cobalt mesh is made in this way.
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The palette of colors of overglaze painting is richer, overglaze painting is applied on glazed linen (a professional term for unpainted white porcelain) and then fired in a muffle furnace at a temperature of 780 to 850 degrees.
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During firing, the paint is fused into the glaze, leaving behind a thin layer of glaze. Paints after a good firing shine (except for special matte paints used only for decorative purposes), do not have any roughness
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The red paint will then be removed and the porcelain will remain white in these areas:
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Kilns are used for firing, which reach 30 meters in length.
Maybe that's what I'd like to see. And in general, while we were walking through the territory of the plant, I noticed photographs from the production on the walls, they looked very picturesque and authentic, and I was looking forward to taking something like that now too.
But it turned out that these photos were taken at a "big" production. The territory of the plant is 5 hectares, everything is occupied by workshops, but there is also a small building where all phases of production are collected in a small area, so that it is convenient to show and conduct tours. That's where we were.
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On the ground floor there is a shop of the plant, everyone can come there and buy something.
Riddle: how much do you think such a figurine costs?
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Series with the Hedgehog in the fog:
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And with the Little Prince, sold at Bukvoed, but here the assortment is better:
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Petersburg souvenirs:
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Taken from mitrofanova_m to the Imperial Porcelain Factory
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