home Ideas Types of porcelain briefly. Properties of porcelain and its application

Types of porcelain briefly. Properties of porcelain and its application

Porcelain is the same type of ceramics that is both white and elegant and durable at the same time. This material has several varieties with their own characteristics - hard, soft, bone and biscuit. We will talk about the latter in more detail.

Biscuit porcelain in the narrow and broad sense

This type of porcelain, like no other, can convey the silkiness, velvety and warmth of human skin. Its structure has nothing to do with dessert - the word "biscuit" is formed from "bis", which means "two", "double". This is due to the peculiarities of its firing.

In a narrow sense, a biscuit is a material not covered with glaze, fired once (which is more typical for modern technologies) or twice. How to distinguish biscuit porcelain? It is distinguished by a snow-white, rough, matte surface, which can even be confused with high-quality marbles. There is nothing to say about the technique of painting biscuit porcelain - the noble material is beautiful even without applying paint or glaze.

In a broader sense, a biscuit can be called any ceramic product that has passed only through the primary (otherwise - biscuit) firing, the characteristic temperature of which is 800-1000 ° C. The result is a strong, heavy, but porous material. Further, repeated and even repeated firing, as well as processing with slip or glaze, can be carried out. But, as we have already mentioned, biscuit porcelain figurines most often remain unglazed.

Biscuit history

France should be called the birthplace of this noble porcelain. The fame of the material was brought by the works of the artist Boucher, which also made it possible to form a special style of French plastic art. In the second half of the 18th century, the ceramics of workshops from the city of Sevres began to attract attention, working with both glazed and biscuit porcelain. These glorious works were distinguished by a floral motif - wreaths, bouquets, garlands, baskets. The works could be deservedly considered remarkable examples of art.

In the era of classicism, biscuit porcelain products became an integral part of the interior of noble houses - furniture decor, crockery, sculptures and sculptural compositions.

Application of biscuit

Due to the porous structure, the biscuit is not used in the manufacture of dishes - the material absorbs water. However, he is very good at the following:

Tinted porcelain of this type is used to make the faces and bodies of biscuit dolls, as well as decorative masks.
This is a popular material for sculpting sculptures, figurines, ornaments, decorative elements - everything that does not need to be protected by a biscuit surface.

Other types of porcelain

Briefly get acquainted with other types of porcelain:

Bone. The formula for this variety of soft porcelain was discovered in England by D. Spoud in the 18th century. Its unusual feature is that 60% of the material consists of the ashes of burnt cow bones, hip bones are most valued here. They do not give a yellowish tint, like horses, and make melting easier. Its main advantage is its extraordinary subtlety, reaching transparency.
Soft. Other names - artificial, artistic, frit. It became known in the 16th century - this is the so-called Medici porcelain. The standard formula was later invented in France in 1673. Its composition is dominated by frit - quartz, vitreous substances, feldspar. Translucency and a pleasant creamy color gives alabaster, flint, sea salt, saltpeter. Soft porcelain retains heat longer, but at the same time it is distinguished by porosity, low strength, even brittleness.
Solid. Also known as "real". We owe its discovery to the German manufactory Meissen. Distinguishes such porcelain great strength, density, resistance to high temperatures and chemical attack. Glaze looks very good on hard porcelain - it is thin and shiny here. Since this coating consists of the same substances, but in a different content, as the material itself, it is homogeneous and adheres tightly to it. Why the glaze from hard porcelain does not exfoliate at all. Moreover, it will be difficult even to repulse it from this material. Biscuit, by the way, is a kind of this group, only unglazed.

Biscuit looks the most natural, the warmest of all types of porcelain. That is why it is so perfect for sculptural compositions, porcelain masks and dolls.

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 a transparent glaze and fired at high temperature up to 1350 degrees.

The palette of colors of overglaze painting is richer, overglaze painting is applied over glazed linen (a professional term for unpainted white porcelain) and then fired in 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 shine (except for special matte paints used only for decorative purposes), do not have any roughness and in the future better resist the mechanical and chemical effects of acidic food products 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 behind the porcelain manufacturing process, namely the need to fire the mixture various kinds soils - those that fuse easily and those that fuse more difficultly - 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.

Kirill Sysoev

Calloused hands do not know boredom!

Content

Many people have a cup or figurine made of bone china at home, but few people know what it is and where to buy it. This type of material is characterized by thin-walled, translucent and sophistication. It was designed by the English ceramic master Josiah Spoud. Dishes made from this material are often labeled Bone chine or Fine bone china. According to its characteristics, it occupies an average value between soft and hard material.

What is bone china

Under this type of porcelain is meant a special kind of hard material with the addition of burnt bone. It is very strong, but at the same time white and transparent. High strength indicators are achieved due to the melting of the main ingredients during the firing process. It was created in the course of attempts to recreate the formula for making the famous Chinese porcelain. At the end of the 18th century, bone ash began to be added to the composition of the material, and in the process of developing technology, a basic formula was developed.

The dishes made from such material do not have the effect of an eggshell, which is achieved due to the fact that the voids between the particles of white clay are filled with bone ash. Thus, bone china is one of the most popular materials, which, due to its whiteness and transparency, has won a leading position in sales in the world market. Services from it can have a pleasant cream shade.

Compound

Before ordering Chinese bone china, pay attention to the composition. The basic formula for the manufacture of this type of material provides for 25% kaolin (special white clay) and feldspar mixed with quartz, 50% burnt animal bones. The first firing is carried out at a temperature of 1200-1300 °C, and the second at 1050-1100 °C. The composition of bone ash in this case includes about 85% calcium phosphate.

The bones that are used as part of the porcelain mass are necessarily subjected to special treatment, as a result of which they begin to burn out - this is necessary to remove the glue from them and heat them up to a temperature of 1000 ° C. At the same time, organic substances burn out, and the structure of the bones changes to the required state. From the resulting mass, using gypsum molds, objects are obtained, on the surface of which, after firing, various patterns are applied.

If necessary, the products are covered with a layer of glaze and sent back to the oven. Flowers and artistic patterns and lines are applied to the product using a decal - a thin film. They also use painting. In general, the thickness of the finished plates, cups and other kitchen utensils is less than the usual porcelain base. Modern technologies provide for the replacement of biological calcium phosphate with mineral one. The quality of the dishes does not change.

Advantages

If you need bone china, it is better to buy it in a specialized online store. Some do mail delivery. Branded items have a number of advantages, due to which they gain popularity among consumers. The material has a softer color and a special whiteness, which is not the case with similar materials. Quality is achieved by adding ground and processed bones to the composition. Many prefer this type of porcelain for its:

smoothness;
airiness;
translucency;
refinement.

What is the difference between bone china and ordinary

This type of porcelain differs from analogues in that a unique component is added to the composition - ground and processed animal bones. Due to the ingredient, the finished product becomes softer, and its walls become thinner. In the light, the material begins to shine a little, which gives the sets airiness and originality, an aristocratic look. Despite all the elegance, fine porcelain has good mechanical strength, making it durable.

How to store

On sale in Moscow, St. Petersburg, you can find a rich assortment of bone-type porcelain products - these are tea sets, dinner sets, decorative vases with various decors, figurines, figurines and more. All of them have an attractive and original look, different shades and can last for many years due to the unique properties of the mixture. Before ordering products, please read the following care tips:

do not put products one on top of the other - plates, cups, saucers, but if such a need arises, then be sure to shift each of them with napkins;
arrange kitchen utensils so that they do not touch each other - there should be a distance between them;
do not wash products made of thin-walled porcelain with hard washcloths, hot water;
for washing it is better not to use chemical detergents, otherwise they can cause damage to the pattern or cause the colors of the cutlery to fade;
products do not tolerate sudden temperature changes, so before brewing a cup of tea or coffee, preheat them - first with warm water, then a little hotter, etc .;
move the bone material when cleaning kitchen furniture with paper towels to prevent chipping;
wipe porcelain with a dry cloth, removing dust from cups, saucers, etc. as carefully as possible;
do not store sets near open flames - as a result of heating, they may be deformed.

Major manufacturers of bone china

The leaders among all manufacturers of products from such porcelain are the British, who were the first to master the technique of making material with the addition of bone ash. Japanese manufacturers also have excellent skills and considerable experience in the field of creating thin-walled porcelain: they changed the established proportion of the bone component in the composition of the porcelain mass. The Japanese came up with a special formula, thanks to which the usual technology has been noticeably improved. Known Manufacturers:

Imperial Porcelain Factory (IPZ). It was founded in 1744 by Empress Elizabeth, the daughter of Peter the Great. At that time, the plant became the first porcelain enterprise in Russia and the third in all of Europe. In the early years, small things were produced there - mostly snuff boxes for the Empress. Over time, a large forge was built and the factory began to produce larger items. The manufactory was reorganized with the accession of Catherine II. The end of the 18th century was the heyday of Russian porcelain, and IPM became one of the leading factories in Europe. As for porcelain with bone ash in its composition, a suitable mass was first developed in Soviet times - in 1968. The first such batch was released by IFZ. Now the enterprise is the only one in Russia that produces bone china mass and objects from it.
Royal Doulton. A company from England, which has been specializing in the production of bone material for a long time and has the status of one of its largest manufacturers and suppliers. Together with the British factory Wedgwood, it is part of an alliance. Founded in 1815, headquartered in Stoke-on-Trent (UK). Royal Doulton produces porcelain objects of various shapes, sizes and purposes. The collections of this company are very popular in many countries.
wedgwood. Another well-known company that produces products from bone china mass. She has been supplying it to the English royal court for over 200 years. The foundation of the Wedgwood brand dates back to 1759, when Joshua Wedgwood rented a manufactory in Burslem. In addition to classical tableware, the company produces avant-garde lines, which include products of non-traditional shape, art objects.
Spode. A brand of bone china tableware from the UK with 200 years of experience. The company offers mugs, plates, sets made to the highest quality standards. The manufactory has existed since 1770. Josiah Spoud (founder) improved the bone china formula and was the first to supply tableware to the English royal court in the 18th century. In 2009, Spode merged with Portmeirion Grou, a well-known luxury porcelain company.
Narumi. Japanese company which was founded in 1911. Its products combine modernity and tradition, West and East, unique beauty and versatility. Since 1965, Narumi has been engaged in mass production porcelain. Narumi bone china products are mostly handcrafted. The brand has become a leader in the field of high-end porcelain Bone China.

Choice

Buying an elegant porcelain product with underglaze painting requires a competent and serious approach, especially if you are going to choose an expensive souvenir. handmade. In addition, it is important to distinguish a fake. This quality creation has a pure translucent white color and gloss with good strength characteristics. Some companies try to combine innovative solutions with traditional recipes and designs. Criterias of choice:

Material color. It should have a warm, light tone and not be too white.
Transparency. If the products are of high quality, then its walls will transmit light well. Holding the thing in your hands, you will clearly see the outlines of your fingers through it.
Study the drawing applied to a porcelain object. Often it is applied by hand, so you can notice the characteristic strokes, the trace of the brush.
Pay attention to the manufacturer. It is desirable that on the back of a porcelain creation there is a marking of one of the well-known brands. If the manufacturer is unfamiliar to you, then postpone the purchase, first study all the information about it.
It is important to make sure the object is smooth, the absence of holes, inclusions, bubbles, scratches, chips on the surface and along the edges.

Where can I buy

You can buy products from bone china mass with a cold white tint at retail outlets specializing in the sale of elite tableware. Look for large stores that often hold promotions, reducing the cost of goods. Visit the outlets yourself: you will have a chance to take a good look at the items and verify the authenticity. You can order the following product from a trusted seller via the Internet. It will be good if you can agree that you will make the main payment after you check the goods.

Price

The cost of bone china varies greatly depending on the manufacturer and type of product. Services, cups and saucers in which are so thin that they can transmit light are in great demand. From the table you can find out the current prices for some types of bone china services:

Set name	What is included	Price in rubles
Royal Bone China Golden embroidery for 6 persons	6 cups, 6 saucers
Japonica Grazia JDYSQH-5 for 6 persons	6 cups, 6 saucers
Royal Aurel Hoarfrost for 6 persons	6 cups, 6 saucers, teapot
Hankook Chinaware Silver Ribbon for 2 persons	2 cups, 2 saucers
Lenardi series Golden Symphony for 6 persons	6 cups, 6 saucers
Royal Aurel Grazia for 6 persons	6 cups, 6 saucers
Lenardi series Silver symphony for 6 persons	6 cups, 6 saucers
Lenardi series Meissen bouquet for 6 persons	6 cups, 6 saucers
Japonica Paradise JDFES-9 for 2 persons	2 cups, 2 saucers
Japonica Grazia JDYSQH-4 for 6 persons	6 cups, 6 saucers, 1 teapot, 1 milk jug, 1 sugar bowl

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Bone china - what is it: properties of dishes

What is porcelain

Porcelain is a special type of ceramics (that is, clay products with special additives that have been fired), which has a number of remarkable properties. First of all, porcelain is impervious to liquids and gases, which makes it possible to produce porcelain tableware. It has high mechanical strength, chemical and thermal resistance and electrical insulating properties.

Porcelain is used not only for the manufacture of high-quality tableware and artistic and decorative items, but also for the creation of sanitary ware, electrical and radio engineering parts, corrosion-resistant chemical technology devices, low-frequency insulators and other utilitarian items.

History of porcelain

Porcelain in English language not for nothing is often called the word china, because its homeland is China. It is believed that various types of ceramics were produced in China as early as 10,000 years ago, but real porcelain did not appear until the 7th century AD. e. With the diligence inherent in Eastern people, the secret of porcelain was kept in the strictest confidence for many centuries, and only at the beginning of the 18th century did porcelain production begin in Europe.

The discovery of European porcelain occurred in 1708 by the Saxon experimenters Chirnhaus and Böttger. Prior to this event, many attempts had been made in Europe to unravel the secret of Chinese porcelain, but the result was materials closer to glass and only remotely resembling porcelain. 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 was yet to be obtained. 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.

The secret of making porcelain

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 just two years later, in 1709 or 1710, the recipe for white porcelain was already determined.

Contemporary porcelain

Now porcelain is made in factories on an industrial scale. 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.

Hard and soft porcelain

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 greater.

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 up to 1300 °C. Soft porcelain is mainly used for making art products, and solid 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.

Methods for decorating porcelain

Porcelain today is painted in several ways: underglaze painting and intraglaze painting of porcelain with high-temperature firing and overglaze painting with low-temperature firing of porcelain. When painting underglaze porcelain, paints are applied directly to biscuit porcelain. Then the porcelain product is covered with a transparent glaze.

Overglaze painting of porcelain with high-temperature and low-temperature firing involves applying paints to an already fired glazed surface of a porcelain product.

The firing of high-temperature overglaze porcelain paints (or intraglaze paints, as they are also called) takes place at 820 - 870 C. At this temperature, the paint eats into the glaze and later better resists the mechanical and chemical effects of acidic foods and alcohol. With this method of painting porcelain, a much richer set of colors is used.

Among the paints for painting porcelain, a group of paints prepared using noble metals stands out. The most common paints using gold, less commonly used silver and platinum paint. Overglaze gold paints are most commonly used for low-temperature firing of porcelain, although there are also intraglaze gold paints.

Porcelain is painted with matte or brilliant gilding. In both cases, it is a viscous black or brown liquid containing 12-32% gold for brilliant porcelain gilding, or 52% fine gold dust and chemically dissolved gold for dull porcelain gilding. During the firing of porcelain, the brilliant gilding begins to sparkle and does not require additional processing in the future. Matte gilding after firing porcelain remains matte and polished with fiberglass made of plastic or sea sand, an agate "pencil". The thickness of matte porcelain gilding is 6 times that of shiny porcelain gilding, and thus the matte porcelain gilding is more decorative and durable. In addition to gold, matte gold paint contains other precious metals that add color to the paint.

History of porcelain in the Russian Empire

In the international literature, the issue of the emergence of porcelain production in Russia is covered in different ways. Often, Russian porcelain and the porcelain industry in Russia are completely ignored, despite their originality and significance in the history of world technology and art.

Attempts to organize the production of porcelain or faience in Russia began under Peter the Great, a great connoisseur of it. On the instructions of Peter 1, Russian foreign agent Yuri Kologrivy tried to find out the secret of porcelain production in Meissen and failed. Despite this, in 1724 the Russian merchant Grebenshchikov founded a faience factory in Moscow at his own expense; it also carried out experiments on the manufacture of porcelain, but they did not receive proper development.

The first manufactory was founded in 1744 by Empress Elizabeth. She was invited to St. Petersburg from Sweden I.-Kr. Gunger, who had previously contributed to institutions in Vienna and Venice. However, he could not resist here, and in 1748 he was released.

After all the failures mentioned earlier, there was only one way, the most difficult and long, but the only reliable one: to organize a search for systematic scientific and technological work, which as a result was supposed to lead to the development of porcelain production technology. For this, a person was needed who had considerable training, possessing sufficient technical initiative and ingenuity. Such was Dmitry Ivanovich Vinogradov, a native of the city of Suzdal.

In 1736 D.I. Vinogradov with his comrades - M.V. Lomonosov and R. Reiser - at the suggestion of the St. Petersburg Academy of Sciences and by imperial decree was sent "to the German lands to study, among other sciences and arts, especially the most important chemistry and metallurgy, to this matter, as far as mining or manuscript art. D.I. Vinogradov studied mainly in Saxony, where there were then “the most glorious manuscript and smelting factories in the entire German state” and where the most skillful teachers and masters of this craft worked at that time. He stayed abroad until 1744 and returned to Russia with certificates and certificates of awarding him the title of “bergmeister”.

Vinogradov was faced with the task of independently resolving all issues related to the creation of a new production. On the basis of physical and chemical ideas about porcelain, he had to develop the composition of the porcelain mass and develop technological methods and methods for making the mass of real porcelain. And one more task arose - the development of glaze, as well as recipes and technologies for the manufacture of ceramic paints of different colors for painting on porcelain. More than a thousand different experiments were performed by D. I. Vinogradov during his work at the “porcelain factory”, as it was then called.

In the works of Vinogradov on the organization of porcelain production in Russia, his search for a “recipe” for porcelain mass is of considerable interest. These works refer mainly to 1746-1750, when he intensively searched for the optimal composition of the mixture, improved the recipe, conducting technological research on the use of clays from various deposits, changing the firing mode, etc. The earliest of all discovered information on the composition of the porcelain mass has a date of January 30, 1746. Probably, since that time, Vinogradov began systematic experimental work to find the optimal composition of Russian porcelain and continued it for 12 years, until his death, i.e. until August 1758

From 1747, Vinogradov began to manufacture trial items from his experimental masses, as can be judged from individual exhibits stored in museums and bearing his brand and date of manufacture (1749 and later). In 1752, the first stage of Vinogradov's work on creating the recipe for the first Russian porcelain and organizing the technological process of its production was completed. It should be noted that when compiling the recipe, Vinogradov tried to encrypt it as much as possible. He did not use the Russian language, but used Italian, Latin, Hebrew, and German words, also using their abbreviations. This is explained by the fact that Vinogradov was given special instructions about the need to classify the work as far as possible.

Vinogradov's success in making porcelain at the porcelain factory at that time was already so significant that on March 19, 1753, an announcement appeared in the St.

In addition to formulating porcelain masses and studying clays from various deposits, Vinogradov developed glaze compositions, technological methods and instructions for washing clays at deposits, conducted tests of various types of fuel for firing porcelain, drafted and built furnaces and furnaces, invented formulas for porcelain paints and solved many related issues. It can be said that he had to develop the entire technological process of porcelain production himself and, moreover, at the same time prepare his assistants, successors and employees of various qualifications and profiles. As a result of “diligent work” (as he himself assessed his work), original Russian porcelain was created, created independently of foreign countries, not by chance, not blindly, but through independent scientific work.

The production of the first period (until about 1760) was limited to small items, usually of the Meissen type. With the reign of Catherine the Great (since 1762), who invited foreign fashion designers for artistic purposes, having replaced a significant part of the staff, an artistic upsurge began. The admiration for French culture also affects porcelain production: the influence of Sevres is noticeable in the forms and noble decors of luxurious tableware. Since about 1780, François-Dominique Rachette, a herald of mature classicism, has been active in the field of plastic arts in St. Petersburg. Under Catherine, one still finds here and there a local tradition, under Paul its trace is completely lost, and the products take on a pronounced French character. A somewhat declining trend at this time is followed by a new upsurge under Alexander I; however, in the third quarter of the 19th century, it was no longer possible to prevent artistic decline.

The private porcelain factory of the Englishman Francis Gardner, founded in 1754 in Verbilki near Moscow, competed with the tsarist manufactory for the quality of goods. In 1780 it was transferred to Tver, and in 1891 it passed into the possession of M. S. Kuznetsov. The plant had a very wide range of products, including those made for the yard. Dinnerware was produced with paintings predominantly in gray-green and light green tones in various combinations with red or light yellow.

Soviet propaganda porcelain

During the Civil War, when the country did not have enough paper even for newspapers and posters, the revolutionary government resorted to the most unusual forms of propaganda. A unique phenomenon in the art of 1918-1921. became propaganda porcelain.

At the State (former Imperial) Porcelain Factory in Petrograd, there were large stocks of unpainted products, which it was decided to use not just as dishes, but primarily as a means of revolutionary agitation. Instead of the usual flowers and shepherdesses, invocative texts of revolutionary slogans appeared: “Proletarians of all countries, unite!”, “Land to the working people!”, “Whoever is not with us, is against us” and others, which, under the skillful brush of artists, formed into a bright decorative ornament.

A group of factory artists headed by Sergei Vasilievich Chekhonin (1878-1936) worked on the creation of works of propaganda porcelain. Before the revolution, he was a member of the World of Art association and was known as a master of book illustrations, a connoisseur of various styles, a connoisseur and collector of folk art. Chekhonin also successfully applied his brilliant mastery of the art of type and the complex language of ornament in porcelain.

Famous artists P. V. Kuznetsov, K. S. Petrov-Vodkin, M. V. Dobuzhinsky, N. I. Altman were engaged in the development of sketches for the paintings of propaganda porcelain. Their works are distinguished by high graphic skill. Already in the first works, new symbols of the young Soviet Republic appeared: hammer and sickle, gear.

The subjects of the paintings by the artist Alexandra Vasilievna Shekatikhina-Pototskaya (1892-1967) are scenes of traditional folk life and characters from Russian fairy tales. In 1921 the Civil War ended. With joyful, bright colors, with a wide energetic brush, the artist painted the heroes of a new, now peaceful life - a sailor and his girlfriend on the May Day holiday, a commissar who changed his rifle for a folder with documents, a guy singing "The Internationale". The artists responded to the famine that broke out in the Volga region in 1921 by creating a whole series of works: “To help the starving population of the Volga region!”, “Hunger”, “Hungry”.

Soviet propaganda porcelain was exhibited at foreign exhibitions, has been exported. These works occupy a worthy place in the collections of the largest museums in Russia and other countries, are desirable for collectors.

By the way

Some manufacturers mark their porcelain items on the bottom with the designation “CHINA. Made in——". Buyers are often confused by this phrase. But connoisseurs know the answer for sure: "CHINA" is the international designation for high-quality bone china. It came from the distorted title of the Chinese emperor, who in ancient times owned a monopoly on the production of table china. Sometimes the words Fine Bone China, which means real bone china, are on the stamp of porcelain manufacturing plants. Now bone china is more popular than ever. This is also true for Royal Fine China tableware. With its pure white color, transparency and lightness, but at the same time, unsurpassed strength, bone china has firmly taken a leading place on the shelves of true connoisseurs and even collectors of porcelain. It is believed that there are no analogues to bone china in its qualities and strength all over the world.

By British standards quality porcelain is called Bone China if the content of bone ash in it exceeds 35%. Bone china with its milky white color, transparency and weightlessness has gained an excellent reputation and a leading position in sales in the world market.

The inscription Fine Bone China means real bone china.

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 it is 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 covered with gilding 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 a relief, with a smooth or figured edge, decorated with underglaze and overglaze ceramic paints, decals, chandeliers, preparations. precious metals and others. 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 ( glassware and 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 added to enhance translucency. To ensure high quality 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 is such a case won't be hurt at all.

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 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 does not contain kaolin and therefore only suitable for porcelain appearance, and its composition 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 products made of baked clay 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 have appeared in different time and in different countries, depending on this 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 they cover their potter from the inside with glaze, which is why, in their opinion, it 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, in rich pagan mounds near the village of Gnezdovo (near Smolensk), fragments of two plates and mugs of white clay were found, covered with glaze and decorated with multi-colored paintings.
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 economy of France 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 some relief to the surface of the product.

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 a decree of the Council of People's Commissars of the RSFSR, among other major 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 with late XIX 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 earthenware, 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 the 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 increase 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. Features 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 with a composition of 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 from non-plastic raw materials a mass with high molding properties, 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 more low temperatures, but not below 1200°C. The first firing is the same - at 900-1000°C. It is known that Brongniart (Sevres Porcelain Factory in France) tested masses in the middle of the last century, firing them even at 1500-1550 ° C, using pegmatite of very fine grinding as a glaze (pegmatite is a light coarse-grained igneous rock, according to physical properties similar to granite).

In addition to the two main types of porcelain, many special types technical porcelains and porcelain-like materials. 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 large bones. cattle, which is part of porcelain. Bone preparation consists of degreasing, steaming and roasting.