Porcelain, history, varieties, technology, marking. Types of porcelain, ceramics and earthenware The current state of affairs

What is porcelain? What is its composition?

1. Porcelain is the noblest and most perfect form of ceramics. It differs from all other species in a number of special properties, for example, in the fact that its mass is absolutely white not only on the surface, but also in the fracture. Transparency is also characteristic in the thinnest places of the shard. Porcelain consists of a mixture of different types of clay and translucent glaze, which is covered with a shard. If the twice-fired porcelain mass is left without glaze, as was customary at some porcelain factories in the manufacture of small plastics, medallions, and less often dishes, then a special type of porcelain is formed - biscuit.
   Depending on the composition of the porcelain mass and glaze, hard and soft porcelain are distinguished.

   Hard porcelain is characterized by strength, strong resistance to temperatures and acids, impermeability, transparency, conchoidal fracture, and, finally, a clear bell sound. In Europe, it was invented in 1708 in Meissen by Johann Friedrich Betger. A prominent representative of hard porcelain is currently the German company SELTMANN.
   Soft porcelain, in comparison with hard, is more transparent, its white color is more delicate, sometimes it has an almost creamy tint. At first, European porcelain was, in most cases, soft, as exemplified by the fine and highly prized wares of old Sèvres. It was invented in the 16th century in Florence (Medici porcelain).
   Bone china is a well-known compromise between hard and soft china. Its composition was discovered in England, and its production began there around 1750. It is harder and harder than soft porcelain and less permeable, but it has a rather soft glaze. Its color is not as white as hard porcelain, but purer than soft porcelain. Bone china was first used in 1748 at Bow by Thomas Fry.
   According to British quality standards, porcelain is called Bone China if its bone ash content exceeds 35%. Porcelain NARUMI / Bone China / contains 47% (!) bone ash, which ensures whiteness, strength and thinness.

2. Farfo#769;r (tur. farfur, fagfur, from Persian fagfur) is a type of ceramics impervious to water and gas. It is translucent in a thin layer. When lightly struck with a wooden stick, it emits a characteristic high-pitched clear sound. Depending on the shape and thickness of the product, the tone may be different.

   Properties

   Porcelain is usually obtained by high-temperature firing of a fine mixture of kaolin, quartz, feldspar 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.

   Hard porcelain (English) Russian , which includes 4766% kaolin, 25% quartz and 25% feldspar, 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).
   soft porcelain

   Soft porcelain (English) Russian more diverse in chemical composition and consists of 2540% kaolin, 45% quartz and 30% feldspar. The firing temperature does not exceed 13001350 C. Soft porcelain is used mainly for the manufacture of artistic products, and hard porcelain is usually used in technology (electrical insulators) and in everyday life (dishes).

   One type of soft porcelain is bone china. , which includes up to 50% bone ash, as well as kaolin, quartz, 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.
   http://www.topauthor.ru/CHto_takoe_farfor_58e9.html (Remove spaces)

3. porcelain is the highest grade of white clay
4. Porcelaińr kind of ceramic, impervious to water and gas. It is translucent in a thin layer. When lightly struck with a wooden stick, it emits a characteristic high-pitched clear sound. Depending on the shape and thickness of the product, the tone may be different.

   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 - it consists of 4766% kaolin, 25% quartz and 25% feldspar, 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).

   Soft porcelain - more diverse in chemical composition and consists of 2540% kaolin, 45% quartz and 30% feldspar. The firing temperature does not exceed 13001350 C. Soft porcelain is used mainly for the manufacture of artistic products, and hard porcelain is usually used in technology (electrical insulators) and in everyday life (dishes).

   Porcelain was first obtained in 620 in China. The method of its manufacture was kept secret for a long time, and only in 1708 did the Saxon experimenters Chirnhaus and Bttger manage to obtain European porcelain.

   Attempts to uncover the secret of oriental porcelain continued for almost two centuries in Italy, France and England. However, the result was materials closer to glass.

   Johann Friedrich Bettger (16821719) began to experiment with porcelain, which in 1707/1708 led to the creation of rothes Porcelain (red porcelain) fine ceramic, jasper porcelain.

   However, real porcelain was yet to be discovered. 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 Francois Xavier d'Entrecol, containing the secret of the technology for the production of Chinese porcelain, made by him in 1712, but became known to the general public only in 1735.

   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, the white porcelain was more or less ready to be made.

   At the end of December 1707, a successful experimental firing of white porcelain was carried out. The first laboratory notes on porcelain mixtures suitable for use date back to January 15, 1708. On April 24, 1708, an order was given to establish a porcelain manufactory in Dresden. The first pieces of porcelain fired in July 1708 were unglazed. By March 1709, Bttger solved this problem, but he did not present glazed porcelain samples to the king until 1710.

   In 1710, at the Easter fair in Leipzig, marketable jasper porcelain dishes were presented, as well as samples of glazed and unglazed white porcelain.

We systematize porcelain according to the composition of raw materials. All porcelain can be divided into three main groups - Oriental porcelain, European hard porcelain and soft porcelain (semi-porcelain).

Hard porcelain, or simply porcelain, is a homogeneous, white, strongly ringing, hard and difficult-melting, with a slight thickness, a very transparent mass, in a break, fatty-shiny, conchoidal, fine-grained; hard porcelain consists mainly of kaolin and feldspar, with an admixture of quartz, lime, etc., and is covered with a hard glaze. The thinner varieties have a feldspar glaze, without lime, resulting in a milky-matte tone; simpler varieties have a perfectly transparent lime glaze.

Porcelain fired without glaze is commercially known under the name "b and c c c and t a"; but for the most part porcelain is glazed, painted, and gilded over glaze or under glaze. French manufacture is distinguished by outstanding merit, especially in Limoges, where each factory has its own specialty, in which it achieves incomparable results. In Germany, Meissen is first, followed by Berlin, as well as Pirkenhammer and Elnbogen in Bohemia.

Masses for porcelain products

Porcelain products are distinguished by fine grinding of the initial mass components, high firing temperature, whiteness, translucency, absence of open porosity, high strength, thermal and chemical resistance. Porcelain masses consist of fine mixtures of kaolin, quartz, feldspar, and other aluminosilicates. The main charm of porcelain is its whiteness and translucency, therefore, the purest ceramic raw materials are used for the manufacture of porcelain products. To increase the plasticity of the mass, part of the kaolin is sometimes replaced with highly plastic white refractory clay or bentonite. Depending on the composition of the mass and the firing temperature, hard porcelain is distinguished, fired at a temperature of 1350-1450 ° C and above, and soft porcelain, the firing temperature of which is below 1350 ° C. Compared to soft, hard porcelain contains more kaolin and less feldspar (up to 36% and up to 28% feldspar, respectively). Soft porcelain is divided into feldspar, low-temperature (high-feldspar), frit, bone, etc.

The first firing of hard porcelain is carried out to a temperature of 850-950°C. Bone china is made from masses containing bone ash, calcium phosphate, feldspar, etc. It is first fired at a temperature of 1230-1250°C, then at a glaze melting temperature of 1050-1150°C. Frit porcelain contains alkaline fusible frits fused from quartz sand, soda, potash, saltpeter, gypsum, and other materials. Frit porcelain is fired first at a higher temperature (1200-1300°C), and at a lower one. Low-temperature porcelain is made from low-caking masses and covered with white deaf zirconium glaze. The main components for its manufacture are kaolin, bentonite, pegmatite, alumina, dolomite and other materials. The crock is sintered, fired once at a temperature of 1160-1180°C, water absorption up to 0.5%.

Semi-porcelain is characterized by a white or colored dense semi-baked sherd covered with a translucent or colored glaze. In terms of composition and firing temperature, it occupies an intermediate position between porcelain and hard feldspar faience. Water absorption is 5-8%. Firing products at a temperature of 1150-1250°C. Porcelain products must have a sintered shard covered with a colorless transparent glaze, sometimes a specially colored shard, or specially coated with colored glazes. The whiteness of porcelain is currently regulated by the standard and is 55-68%. Products are made smooth or with relief, with a smooth or figured edge, decorated with underglaze and overglaze ceramic paints, decals, chandeliers, preparations of precious metals, etc. Porcelain products are made mainly in two ways: casting and molding using a template in plaster molds. Products from bone and frit china, due to the absence or small amount of plastic materials in the composition, are made only by casting, sometimes with adhesive additives. The mechanical strength of soft porcelain is one and a half times less than hard porcelain.

Hard porcelain, depending on the purpose, is divided into 3 groups:
1. Economic and artistic (dishes, figurines, vases).
2. Electrotechnical (insulators).
3. Chemical porcelain (laboratory glassware, etc.).

The most harmful impurities in porcelain are Fe2O3 and TiO2. To improve the molding properties, along with kaolin, highly plastic white-burning refractory clays and plasticizers (4-5% bentonite) are added to the porcelain mass. Feldspar or pegmatite are used as fluxes for the production of porcelain. Sometimes, dolomite, calcareous spar, etc. are additionally added to enhance translucency. To ensure the high quality of products, raw materials are subjected to fine grinding, the fineness of which is controlled by a sieve of 10,000 holes / cm2. Due to the very short sintering interval of frit porcelain, in order to prevent deformations, the products are fired in special clay molds, with coasters. The marriage of products after firing often exceeds 50%.

Bone china it is distinguished by high whiteness, translucence and decorative effect, but such porcelain is easily deformed during firing. Separate types of unglazed bone china are called pariana (opaque material with a yellowish tint) and carrara (reminiscent of white Carrara marble). Bone china is used to make tea and coffee sets, as well as biscuit sculptures. For the manufacture of tableware, this material is not used, since it is unstable to the action of acids and alkalis.

High feldspar porcelain resembles hard porcelain and is distinguished by a lower content of clay matter and a higher content of quartz and feldspar. It is produced according to the scheme for the production of hard porcelain, and the temperature of the first firing is 950-1000°C, and the second is 1250-1300°C. It has less mechanical strength and heat resistance than porcelain, but has greater translucency and greater decorative possibilities (lower poured firing temperature). It is used for the manufacture of expensive sets, sculptures, etc.
Porcelain masses in some cases can be colored with ceramic pigments based on cobalt, chromium, nickel, etc., depending on the maximum firing temperature. Finished porcelain masses can be used as a material for the manufacture of decorative items with crystalline and matte glazes, firing them at a temperature of 1100-1200T.

Soft porcelain, embraces two completely different varieties, more or less approaching porcelain in color, transparency and glaze, but very sensitive to rapid changes in temperature. Before hard porcelain appeared in Europe, soft porcelain was used. If you run a knife over soft porcelain, the glaze cracks; in this way it is most easily distinguished from hard porcelain, the glaze of which in such a case will not suffer in the least.

French soft porcelain consists of an incompletely molten, vitreous, fine-grained mass, with a lead, crystal-like, siliceous glaze. The fusible glaze, which makes it similar in appearance to Chinese porcelain, allows for thick writing and much more delicate tones than hard porcelain. The composition of English soft porcelain (bone china) includes burnt bone, phosphate salts, kaolin, etc. It occupies a place between the stone mass and hard porcelain, resembles white alabaster and is extremely transparent. For painting, it offers the same advantages as French and German, but is especially favorable for gilding and jewelry with precious stones.

Main component Oriental and European hard porcelain is kaolin (non-melting china clay and feldspar). European porcelain has more kaolin than Eastern porcelain and requires a hotter fire when fired. This gives him transparency, but in such a fire all colors burn out, except for blue. Therefore, European porcelain has to be painted on top of the glaze, while Oriental porcelain allows the use of a number of colors for underglaze painting.

European semi-porcelain It does not contain kaolin, and therefore it is suitable for porcelain only in appearance, but in its composition it is closer to glass. During firing, it does not require a high temperature, which allows the use of a larger amount of paints, which, fusing with the glaze, give the painting a special transparency and brilliance.

If we try to classify fired clay products in order of increasing complexity of their manufacturing technology, we get the following scheme: manual primitive molding and fire firing; pottery and furnace firing; majolica; semi-faience; faience; porcelain. These technologies appeared at different times and in different countries, depending on this, having significant features. Today, almost all of them exist in modern versions, and in any, even the most primitive technique, using the most uncomplicated technology, a talented ceramist can achieve great success. Terms denoting products made of clay have long and firmly entered the Russian language. So, as they say, let's deal with the terms first.

The most general concept, which includes all products and materials obtained by sintering clays and their mixtures with mineral additives, as well as oxides and other inorganic compounds, is ceramics. Further, if you follow the chronology in the development of the properties and capabilities of clay as a material by people, there are stucco and pottery. I think everyone understands that pottery is made on a potter's wheel, and stucco molded by hand. But nevertheless, there is one nuance. Pottery is a term for items made on the potter's wheel without further application of glaze. And faience, and majolica, and even porcelain can also be made using a potter's wheel, but we do not call them pottery. The main distinguishing feature is that faience and majolica are glazed. Moreover, it is very difficult to draw a line and determine by what percentage it is necessary to cover the pottery with glaze and paint so that it turns into majolica.

Some modern masters cover their pottery from the inside with glaze, which, in their opinion, does not turn into majolica. The name of this pottery comes from the name of the island of Mallorca, where, under the influence of the Moriscos from the city of Malaga (Spain), in the 14th-15th centuries, the production of ceramic products from naturally colored clays, completely covered with dull tin glaze and painted, flourished. Majolica production has spread in Northern Italy, having received special development in the vicinity of the cities of Faenza and Urbino. I think you guessed that it was the name of the city of Faenza that gave the name to the next type of ceramics - faience. But here I must make a reservation: it has not yet been fully clarified what appeared earlier - majolica or faience - not as names, but as types of ceramics. Indeed, majolica is still sometimes called "simple faience", which means that faience is a more general concept that includes majolica.

Today, majolica is called ceramic products made of naturally colored fusible clays, the red shard of which is covered with a dull glaze, with a water absorption of 10-15 percent. Faience is called ceramic, covered with transparent glaze products with water absorption from 9 to 12 percent. The color of faience can be different: mostly light tones to white. The composition of faience masses can be divided into three groups: clay ancient faience - from clay and ground fired flint or quartz; calcareous, or soft, faience (typical medieval) - made of clay, burnt flint or quartz and marl or chalk; feldspar, or hard, - from clay, flint or quartz and feldspar, first made at the beginning of the 18th century in Germany.

The most ancient clay vessels covered with glaze, or, as it was otherwise called, with glaze, were made in Egypt. From Egypt, the art of glazing came to Babylonia and Assyria, and from there it penetrated into Persia, where it flourished mainly in the field of building art. Different literary sources assess the use of glaze by the Greeks and Romans differently. For example, the German researcher of the history of faience A.N. Kube believed that the Greeks and Romans knew the technology of using glaze, but their exclusive love for a clean shard limited them in its use. And when ancient culture collapsed, the art of glazing died for Europe along with it. But in the Middle Ages, faience reappears and again in the East. At the beginning of the 13th century, the Arabs who crossed over from Africa, after a seven-year stubborn struggle, took possession of the Iberian Peninsula. And now, together with the Arabs, faience production appears in Spain, which will remain in the grip of oriental traditions for a long time to come. In the end, Spanish-Moorish ceramics appear - a kind of bridge between East and West. Then, from Spain, faience production penetrated into Italy, where in the middle of the 16th century it reached its peak in the so-called Italian majolica.

Glazed pottery has been known in Ancient Russia since the 10th century. So, at the end of the 19th century, fragments of two plates and mugs of white clay, covered with glaze and decorated with multi-colored paintings, were found in rich pagan burial mounds near the village of Gnezdovo (near Smolensk).
The production of majolica, which passed from Italy to other countries of central Europe, further developed into the production of faience with a skull in white or cream color, covered with a transparent lead glaze. This is how French faiences, the famous Dutch Delft faiences, German and English faiences arose. Even oddities often contributed to the development of faience production in Europe. So at the end of the 17th - beginning of the 18th century, wars undermined the French economy and, in need of funds, Louis XIV forbade the use of gold and silver utensils, which led to the rapid development of the production of ceramics, and in particular faience.

In the 17th century, earthenware covered with transparent lead glaze was called semi-faience. The prefix "semi" did not contain anything disparaging or indicating low quality, it only indicated the technical differences between these faiences and "real" faiences covered with opaque tin glaze. The highest results in the use of transparent lead glazes were achieved in Germany by the Hirsch-Vogel family and in France by Bernard Palissy.

The so-called Turkish semi-faience (XVI-XVII centuries) belongs to the group of soft faience, which was made from a mixture of red-burning clay with chalk. Usually this semi-faience was engobed or covered with tin glaze and decorated with thick pastes using ocher (bolus), which gave the surface of the product some relief.

In Europe, faience production reached its peak in England in the 17th century, when the English ceramist Josiah Wedgwood (Wedgwood) invented high-quality faience masses ("cream", "basalt", "jasper"). His most remarkable work is in Russia. This is a table service of 952 items, made by order of Catherine II (in England it was called "Russian"). Each piece of this service bears the author's personal stamp - a green frog.

In Russia, the 18th century was the time of birth and rapid development of faience production. The first plant known to us was founded in Moscow in 1724 by the merchant of the first guild, Afanasy Grebenshchikov. In 1752, the State Faience Factory was opened in St. Petersburg, and then the Imperial Faience Factory, where Dmitry Vinogradov worked. Since 1757, the factory of Ivan Sukharev began to work, which was previously engaged in the manufacture of paints. In the second half of the 18th century, the production of numerous factories and workshops in Gzhel near Moscow became mass. In August 1809, in the village of Domkino, Tver province, one of the most interesting Russian faience factories arose, which soon took a leading place in the domestic ceramic business - the future Konakovo (Kuznetsovsky) factory. And in September 1810, A.Ya. became the owner of this faience factory. Auerbach, who from the very first days carried out a number of measures to strengthen his enterprise.

In 1870, the Auerbach factory was sold to M.S. Kuznetsov - a bright, colorful personality, typical of the period of development of capitalism in Russia. M.S. Kuznetsov attached this enterprise to the factories he had in Dulevo, Vladimir province (founded in 1832) and in Riga (founded in 1843). By this time, Kuznetsov enterprises were already prominent in Russia. The former Auerbach plant in the Tver province became one of the enterprises of a vast Kuznetsov company, which included: a ceramic enterprise in the village of Budy, Kharkov province, a Gardner factory in the village of Verbilki, Dmitrovsky district, a factory in the city of Slavyansk, Chernigov province, a factory in the village of Pesochnaya, Yaroslavl province, a faience factory in the village of Pesochnya, Kaluga province. In 1889, the M.S. Kuznetsov Association for the Production of Porcelain and Faience Products was established with a board in Moscow. In 1918, by decree of the Council of People's Commissars of the RSFSR, among other large industrial enterprises, the Kuznetsov factory in the Tver province was nationalized. But only in the 1930s the factory started production and young talented artists I. Frikh-Khar, I. Chaikov, I. Efimov, V. Favorsky, V. Filyanskaya, P. Kozhin, S. Lebedeva, M. Kholodnaya came here.

Some faience factories, along with faience, began to produce porcelain products from the middle of the 18th century. Faience differs from porcelain in that the earthenware mass contains much more clay. In "clay" faience, the content of clay reached 85 percent, the firing temperature was 950-960 ° C, such faience was covered with colored deaf glaze. This faience was characterized by high porosity and low mechanical strength. The limestone faience of the Middle Ages contained, in addition to clay and flint, another 10-35 percent limestone or chalk; its firing temperature reached 1100-1160°C; the shard was porous (19-22% in terms of water absorption) and low-strength. Hard, or feldspar, faience became widespread from the end of the 19th century. Chalk has been partially or completely replaced by feldspar. Hard faience was fired twice: first at a higher temperature (1230-1280°C) - to obtain a high-quality shard, and secondly - at a lower temperature (1050-1150°C) - only to melt the glaze.

Unlike European faience, which is not translucent in the shard, Persian faience, the production of which went through a long period of rise and prosperity (from the 10th to the 17th century), had a well-translucent shard. Persian faience was prepared from a mass rich in quartz with a small addition of glazed clay after firing. Products were covered with a thin layer of white engobe and transparent alkaline glaze with a luster metallic sheen or lead-tin glaze. For the first time, the technology of lustred ceramics was described in a treatise of the 12th century by Abul-Fazl Khubaish Tiflisi. If we talk about the shortcomings of faience, then first of all it is necessary to say about its porosity, which leads to the absorption of moisture from the air, which leads to some swelling (0.016-0.086% of the volume), to rupture of the glaze and to the appearance of a crack (small cracks). glaze), increasing over time. On all ancient faience products, the glaze is covered with a zeca mesh, which for collectors is a kind of sign of the authenticity of the ancient origin of old faience or majolica.
Glaze for faience is used fritted fusible. The introduction of 3-4 percent of chalk, magnesite and dolomite into the mass, as well as an increase in the firing temperature by 20-40 ° C, can eliminate the cake. Usually faience products reach the limit of their volume expansion in two to three years.

At the end of this brief information about faience, I will give the composition of the faience masses of some factories. Barmin's factory, Moscow, 1876: 3 poods of Glukhov clay, 1 pood 20 pounds of English clay, 6 poods of sand, 6 poods of flask; Konakovo plant, mid-19th century: clay 29%, kaolin 32.5%, quartz waste 32.5%, 6% cullet, firing at 1250-1280°C. Let's continue our acquaintance with the types of ceramics. Porcelain is the most complex in composition, the most high-temperature firing and the most difficult material for a person to get. Distinctive features of porcelain - white color, lack of porosity, translucency, strength, heat resistance and chemical resistance - are determined both by the composition of the feedstock and by the technology of its processing. Porcelain was invented in China during the Han period (206 BC - 221 AD). There are the following periods in Chinese porcelain production, named after the ruling dynasties: Tang (618 - 907), Song (960 - 1279), Ming (1367 - 1643), Kang-Hsi (1662-1722), Chieng-Lung (1723 - 1795 ) and a new one - from 1795. Porcelain reached its heyday in the development of form and decoration during the Kang-Hsi period.

Rarely encountered favorable composition of "porcelain stone" (nan-kang), large reserves of which are located near the original place of porcelain production (Jindezhen), greatly simplifies the composition and preparation of porcelain mass with the addition of kaolin. Mineralogically, nan-kan is a sericite sandstone of composition: 75.06 percent silica, 0.05 percent titanium oxide, 16.01 percent alumina, 0.41 percent iron oxide, 0.28 percent calcium oxide, 0.60 percent magnesium oxide, 1.97 percent sodium oxide, 3.3 percent potassium oxide and other impurities - 2.2 percent. The mass was aged in a closed state in the ground for 100 years, which made it possible to obtain a mass with high molding properties from non-plastic raw materials, which made it possible to manufacture (already in the Song period) the famous "eggshell porcelain", that is, products with very thin walls. Chinese ceramists of the school of Professor Zhou-Zhen found that the grinding of "porcelain stone" in a modern ball mill does not impart to the porcelain mass the plasticity and coherence that is achieved when this stone is crushed in mortars and aged, as was done in the old days.

Naturally, the high cost of Chinese porcelain imported to Europe in the 15th - 17th centuries (a whole company of soldiers could be given away for one porcelain vase) caused attempts at imitation. Such are Medici soft porcelain, French fritted porcelain with the addition of marl clay and chalk to glass, Réaumur porcelain, etc. In 1708, the Meissen alchemist I.F. Betger managed to make a prototype of European porcelain from kaolin, sand and chalk; but already from 1720 chalk was replaced by feldspar, and real hard porcelain was obtained. The manufacture was strictly classified. In the 18th century, large manufactories developed, and later factories in Meissen itself, famous for its "Saxon" porcelain.

In Russia, the composition of porcelain was independently developed in 1744 by D.I. Vinogradov, who set up porcelain production at the Imperial Factory near St. Petersburg (now the Porcelain Factory named after M.V. Lomonosov). The recipe for porcelain in Vinogradov's entry is as follows: "Take calcined quartz 768 hours, prepared clay 384 hours, gerbil, sifted alabaster 74 hours." In this mass, quartz plays the role of a leaner, alabaster - the role of flux, clay - the role of a binder plastic additive. The preparation of clay (a kind of Gzhel white-burning gerbil) consisted in elutriation.

Modern technologists distinguish between two main varieties of porcelain - hard (with a small amount of flux), fired during poured firing at a temperature of 1380-1460 ° C, and soft (with an increased amount of flux), fired during poured firing and at lower temperatures, but not lower. 1200°C. The first firing is the same - at 900-1000°C. It is known that Brongniard (Sevres Porcelain Factory in France) tested masses in the middle of the last century, firing them even at 1500-1550 ° C, using very finely ground pegmatite as a glaze (pegmatite is a light coarse-grained igneous rock, similar in physical properties to granite ).

In addition to the two main types of porcelain, many special types of technical porcelains and porcelain-like materials are currently known. For example, semi-porcelain, or low-temperature Vitries-China porcelain, or English bone china, which began to be produced by I. Spode (second) in 1759) in the Stoke-on-Trent area, where most of the English porcelain factories are currently concentrated . Bone china has high decorative qualities, and they depend on the correct preparation of the ashes of the bones of cattle, which is part of the porcelain. Bone preparation consists of degreasing, steaming and roasting.

The term "porcelain" refers to a wide range of ceramic products that are made at high temperatures. Their distinguishing features are a smooth surface and low porosity. These properties of porcelain are widely demanded to this day. It is difficult to find some branch of industry or the national economy, wherever it is used.

The most common decorative porcelain, as well as chemical glassware, dental crowns and electrical insulators. Usually white or off-white, for “baking” this wonderful material arrives as an unpresentable piece of ceramics, which will acquire its usual form only after roasting in high-temperature ovens.

Advantages of Chinese services

In this article, we will discuss the properties and types of porcelain. You will understand why this material was so popular all over the world that huge expeditions were equipped to buy it. For a beautiful service, which today you can buy in any store, then you could get killed.

Oddly enough, but the products of Chinese masters with today's ceramics are only relatives, but not direct ones. To be convinced of this, it is enough to recall the basic properties of porcelain that came out of the workshops of the Celestial Empire. The materials are very similar to each other: both modern and ancient porcelain can be glazed or "natural". But simple ceramics are much softer. And you can't make a high-quality service out of it.

Why is this happening?

Such properties of porcelain as strength and heat resistance are the result of high temperatures at which true Chinese ceramics are produced. It is produced at a temperature of 2,650 degrees Fahrenheit (1,454 degrees Celsius). Compare that to 2,200 degrees Fahrenheit (1,204 degrees Celsius) for plain porcelain. Since the second material is of lower quality, it is not used in the chemical industry and other technological branches of science. In addition, it is Chinese porcelain of the highest quality that is transparent to the light. Rough ceramics cannot give such an effect.

Spy passions

"Hard paste", or true porcelain, first appeared in China in times (618-907). But really high-quality products, in their properties in no way inferior to modern ones, became known to the world only during the Yuan Dynasty (1279-1368). Early Chinese porcelain consisted of kaolin (china clay) and pegmatite, a rough type of granite.

It was unknown to European potters until the import of Chinese equipment during the Middle Ages. Europeans tried to duplicate the properties of porcelain, but did not succeed in this matter. Since they were not able to analyze its chemical composition, the products they produced resembled elegant, fragile and at the same time durable dishes only externally. It turned out like that. Real spy wars unfolded in order to get the secret of true porcelain production, but the Chinese kept their secret more than life.

Why was this material so popular? The reason is the excellent physical properties of porcelain. It is stronger than ordinary ceramics, has a high thermal conductivity, which makes it possible to brew excellent tea in teapots from it. In addition, due to the glaze, porcelain has an extremely low soiling, staining only under the influence of synthetic pigments. Cups from ancient Chinese sets retain their whiteness after many centuries.

Erzatsy

After mixing glass with tin oxide to make an opaque material, European artisans tried to combine clay and these alternatives became known as "soft paste", or faux porcelain. But two unpleasant circumstances were upsetting: all these materials turned out to be too soft, it was impossible to make really thin, elegant products from them, and the production costs were too high. In a word, the properties of "ersatz-type" porcelain were very far from perfect.

There is evidence that our masters also mastered the art of producing true porcelain, but all the secrets of Russian ceramics were lost during the period of the Tatar-Mongol invasion, when entire cities were burned along with all their inhabitants. The British were also able to achieve a certain breakthrough. They created a "bone" kind of material.

But what are the main properties of which provided him with incredible popularity in old Europe?

History of creation

In 1707, two Germans named Ehrenfried Walther von Chimhaus and Johann Friedrich Bottger discover a more "sane" production method that uses clay and finely ground feldspar. In the 17th century, English artisans learned through experiments that porcelain could be made almost identical to Chinese porcelain by adding finely ground burnt bones to this mixture.

Moreover, it later turned out that the English version makes it possible to produce transparent ceramics at much lower temperatures, which significantly reduced the cost of production. In addition, porcelain from Foggy Albion fought much worse, was much stronger. So it is not surprising that the British soon filled up half of the Old and almost the entire New World with their services.

What are the properties of bone china? Firstly, products made from it are distinguished by high strength with low weight and thin-walled. Secondly, this type of ceramics cannot be used in the chemical industry, since the substances in its composition react with acids and alkalis.

Raw material

As we have already said, the main components of this material are extremely simple: clay, feldspar, minerals with calcium content. Until now, various companies compete with each other, as it was quickly established that the properties of porcelain and earthenware can be radically changed by adding new elements to its composition. Of course, if the experience is successful.

Even though the composition of the clay varies depending on where it is mined, it still turns into glass (which makes the final product smooth) only at extremely high temperatures. But this is true only for those cases when clays are not mixed with materials whose vitrification threshold is lower. Unlike glass, however, clay is thermally stable, meaning it retains its shape even when heated to a high temperature.

So this material is really unique because it combines the low porosity of glass with the stability and relative strength of simple ceramics. Kaolin, a hydroaluminosilicate, has been used as the main type of raw material at all times. (containing aluminum silicate) and flint, a type of hard quartz, are extremely important ingredients in any type of porcelain. They melt during heating, binding the material into a single whole.

Quartz - the "heart" of porcelain

This is a guarantee of strength. The properties of porcelain (and its use) are largely due to this very characteristic: it breaks poorly (when compared with glass), and small distances between particles ensure the impermeability of the material to air, water, and other compounds.

Quartz is an "alloy" of oxygen and silicon, the two most abundant elements in the earth's crust. It has three functional forms: quartz itself (crystals), opal (amorphous variety) and sand (mixed, dirty fraction). In general, quartz has long been used in handicraft production. Porcelain may also contain alumina and steatite, more commonly known as "soapstone".

Manufacturing process

After the raw material is selected and weighed, it goes to production. First, it is cleaned and ground to very fine fractions. After that, all components are mixed in the required proportion, depending both on the production conditions and on the characteristics of the final products. As soon as the latter are formed, they can be sent to the kiln immediately, or they are pre-cleaned and then covered with a layer of glaze.

Of course, crushed glass first acts in its role. And only after that, future vases, cups, toilet bowls and dental crowns are sent to the furnace mouth. Now let's look at each stage separately. After all, the properties of porcelain and its application depend on their success!

Crushing of raw materials

Perhaps this is one of the most important operations, since the quality of the final product depends on the thoroughness of its implementation. Crushing is carried out using huge mechanical drum crushers. On the second pass, the particle size is brought to 0.25 cm. To turn the feedstock into fine dust, special ball crushers are used. These are huge steel cylinders filled with metal balls. When the whole structure rotates, the particles of raw materials turn into a homogeneous mass of extremely fine grinding.

Cleaning and mixing

The mixture is passed through fine filters, and then fed to a special "conveyor", which is an inclined steel sheets. They vibrate, as a result of which the raw materials are not only automatically mixed, but also sorted, since the largest particles are pushed up. If a wetted material supply is required, water is automatically sprayed into the line.

Sometimes filters with powerful magnets are used, since the latter can remove the smallest iron impurities. The latter, if it gets into the finished product, will give it an undesirable red tint. After that, the finished products are sent to the kiln, where they are fired at the temperatures already indicated by us.

On what conditions of production can the properties of products depend?

It should be noted that during the final firing, many processes take place, on which the properties directly depend. Firstly, all carbon organic impurities are burned, excess water is evaporated, various gaseous fractions come out of the thickness of the future product. If at the same time the temperature is not brought to 1100 degrees Celsius, then silicon and other glaze components will not be able to melt, which means they will not form a smooth and chemically neutral layer on the ceramic surface.

In addition, these connections are necessary to reduce the distance between the particles of materials, to more reliably connect them to each other. After the desired density is reached, the product is cooled, as a result of which the glaze “pulls together”, becomes smooth and especially durable.

Results

So why are we describing all this? The thing is that the properties of this material are closely dependent on the features and conditions of its manufacture. For example, strength depends on the percentage of feldspar content in the mass, and the number of pores in porcelain is the smaller, the more feldspar. As the quartz and the residue obtained from the decomposition of the clay substance dissolve in the glass, the skeleton of the porcelain material becomes weaker and the deformations increase. Depending on the fineness of grinding of quartz, composition of the mass, temperature and duration of firing, the composition of the vitreous phase includes from 15 to 40% of all quartz introduced into the mass. The more it is, the porcelain is thinner and "airier".

Properties as dielectrics are characterized mainly by resistance to the passage of electric current in the material and on the surface of the insulator. Distinguish between specific volume and specific surface resistance of porcelain.

In addition, the chemical properties of porcelain are of great practical importance. More precisely, their absence. Glazed ceramics with the addition of a large amount of feldspar and quartz are chemically neutral. Do you think why the mortars of pharmacists and chemists are made of this material? It is much stronger than glass, but it does not react.

The current state of affairs

Today, ceramics (and porcelain in particular) is experiencing a rebirth. It turned out that these materials can be used in the production of various types of microelectronics. The importance of this for modern civilization does not need to be explained. Scientists also found that when certain additives are added, the strength of porcelain increases exponentially. Currently, even promising research is underway in the field of creating new types of armor based on it. So not toilet bowls alone!

Finally, this material is becoming increasingly important in medicine. Various prostheses and magnificent dental crowns - the demand for them is increasing every year. So it will remain relevant for a very long time.

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 stroke painting, the paint is diluted with a brush 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.

  Ceramics is a category of materials that includes porcelain and faience. These are two fired products of the same type, similar in their external data, but at the same time fundamentally different in physical qualities. What are these differences?

  Porcelain

  Any ceramic product is obtained by high-temperature sintering of clay (its mixtures) with mineral additives and inorganic components. If a mixture of plastic clay, kaolin (white clay), quartz and feldspar (silicate) with an equal or greater percentage of minerals was involved in the sintering process, then porcelain is obtained as a result of firing. This is a high-strength, non-porous, thin, translucent (if porcelain is brought to the light, it will be translucent), heat-resistant material, which differs from others in its light weight.

  porcelain figurine

  Faience

  But if a mixture of clay (80-85% of the total mass), quartz, feldspar and a small amount of kaolin participated in the process of sintering ceramics, then faience is obtained as a result of firing. It is a finely porous material fired at temperatures up to 1280°C. The presence of pores makes faience more fragile, rough and water-absorbing (about 12%) material, which must be covered with a thick layer of glaze in order to eliminate imperfections. It is heavy, has a matte finish and is opaque.

  
  Crockery

  Differences

  Depending on the proportions of the components of the mixture listed above, technologists can obtain soft and hard porcelain. Products made of soft porcelain are fired in a kiln at temperatures below 1350°C, while those made of hard porcelain are fired at 1350°C - 1450°C. The soft variety is more fragile and sensitive to sudden temperature changes, it is conditionally classified as porous ceramics (there is a small number of small pores), the glaze of which is destroyed by mechanical stress. Because of these physical characteristics, soft porcelain is only used for valuable pieces of art, not tableware.

  Hard grades of porcelain contain up to 66% kaolin (but not less than 47%). This variety refers to dense non-porous ceramics, which makes it more resistant to physical impact. The material is also transparent, "weightless", has a smooth white surface. Hard varieties are used for the production of dishes, decorative items (vases, dishes), electrical insulators and even plumbing. But there is also a special material "biscuit" - a hard type of porcelain that is not covered with glaze. It is a matte material used to make sculptures and ornaments.

  Any porcelain mass is always white, since when dyes are added to the mixture, it is impossible to achieve the required transparency, thinness and, at the same time, the strength of the material. All colored products are painted with special paints on glaze after firing. Porcelain "sounds high" when struck lightly.

  The mass for making earthenware is white, but often colored dyes are added to it, which makes it possible to produce products of any shades. In addition, silicon, quartz, lime, feldspar or fireclay, magnesia, carbon dioxide can be added to the mixture. Depending on the components, varieties are also distinguished, for example, alumina and lime faience. They also affect the quality of the material, its porosity, fragility, water absorption. Due to the richness of the varieties of material, faience is used to produce dishes, tiles, tiles, figurines and so on.

  Findings site

  1. Porcelain has unique and valuable decorative characteristics.
  2. Faience absorbs moisture, which makes it very sensitive to temperature changes and less hygienic.
  3. Porcelain is lighter and at the same time mechanically stronger than faience.
  4. Faience is less valuable because the production process is less labor intensive and the materials used are not as expensive.
  5. Faience is more practical and decoratively diverse than porcelain.