In chemistry for grade 11 (O.S. Gabrielyan, 2007),
task №5
to the chapter " §10 Solids».

Do you know anyone who is not familiar with glass? I think no. Every day we come into contact with this magical material in one way or another, and our life without it is unthinkable. How did it come into being and who invented it?

I will tell you about this briefly, since my main ode will be dedicated to the bottle - the most perfect, impeccable and harmonious creation of man in the entire history of his existence.

Glass has been known to people for about 55 centuries. The most ancient samples were discovered in Egypt. Glass items dating back to 2000 BC have been found in India, Korea, and Japan. According to excavations, the secrets of glass production were known in Rus' more than a thousand years ago. There are many versions about the origin of glass, here are some of them:

Man-made glass was discovered by accident, as a by-product of other crafts. Firing of clay products took place in ordinary pits dug in the sand, and straw or reed served as fuel. The ash (alkali) formed during combustion produces a glassy mass upon high-temperature contact with sand.

Others consider glass to be a by-product of copper smelting.

It was an accident, at least as the ancient legend tells it as retold by Pliny the Elder (79 - 23 BC). It says that a group of Phoenician merchants, returning from Egypt with a large load of blocks of saltpeter, stopped to rest on the bank of a river in Syria. Unable to find stones to set the dishes for cooking dinner, they decided to use blocks from their cargo. The fire, spread under the mass of saltpeter, continued to burn all night. In the morning, the merchants were amazed to see that instead of river sand and ash there was a new shiny and transparent material - glass had formed. Syria was one of the first places for glass production on earth (according to other versions, it was the north-west of Iran), and Phoenician traders sold glass products in all Mediterranean countries.

In any case, the invention of glass in 2200 BC. included in the list of the most significant discoveries in the history of the evolution of materials. Following ceramics, glass became the second processed non-metal known at that time.

Another country where glass making has been known since ancient times was Egypt. Glass beads and amulets have been found in tombs dating back to 7000 BC. Around 1500 BC The Egyptians were already making their own glass. To do this, they used a mixture of crushed quartz pebbles and sand. They also discovered that if they added cobalt, copper or manganese to this mixture, they could produce blue, green and purple colored glass. After 1200 BC The Egyptians learned to cast glass in glass molds. But the glass blowing tube was unknown until the beginning of the Christian era, when it was invented by the Phoenicians. In some countries of the world, such tubes are still used in glassblowing workshops. The Romans were great craftsmen in glass making, and they were the first to make thin window glass. Art products Venice became famous for glass. In the 13th century, numerous glass factories moved from Venice to the neighboring island of Murano, due to frequent fires caused by the round-the-clock operation of glass furnaces. Italian Murano is still a center for the manufacture of handmade glass pieces.

In the 16th century, glass was already being produced throughout Europe. Currently, Bohemian glass produced in the Czech Republic is widely known for its beauty. Further, thanks to the invention by the Englishman George Ravencroft in 1674 of a new method of producing crystal, a higher quality composition of glass melt was obtained than that of the Italian masters.

Ravencroft replaced potash with highly concentrated lead oxide and obtained glass with highly reflective properties, which was very amenable to deep cutting and engraving. The main countries producing high-quality crystal tableware made from glass with a high lead content are Sweden, England and Ireland.

The first mention of a Russian glass factory - it was built near Moscow near the village of Dukhanino - dates back to 1634.

And only in late XIX century, glassmaking began to develop from artisanal into mass industrial production and became a subject of everyday life.

Glass is one of the oldest materials known to man. Now almost any shape and size is possible. Around 4000 BC. glazed ones appeared pottery with a smooth glassy coating, First glassware dates back to 1500 BC.

Glass was also brewed in Kievan Rus. However, the Mongol-Tatar yoke stopped the development of glass production for several centuries, and again it was revived in Russia in the 17th century based on the traditions of European glassmaking.

In 1634-39, in the village of Dukhanino near Moscow, the Swedish master Julius Koyet built the first glass factory, which produced window glass and apothecary glassware.

In 1669, by decree of Tsar Alexei Mikhailovich, a glass factory was built in Izmailovo. Luxurious items for the royal court were produced here. Particularly valued at that time were “amusing” vessels made by foreign masters and their Russian students in the traditions of thin and elegant Venetian glass. The “cracker” cups were distinguished by intricate moldings and were equipped with a system of hollow rods with their own secret.

With the emergence of the new capital, the center of glass production moved to St. Petersburg. In the first half of the 18th century, several factories already existed here: Yamburg and Zhabinsky near St. Petersburg, and in the early 1730s a factory was built in the capital itself. St. Petersburg factories produced mainly tall ceremonial goblets made of colorless glass, decorated with matte engravings with images of portraits of reigning persons, with coats of arms and monograms, with all kinds of emblems, with floral ornaments.” The decorative effect of the products was enhanced by gilding.

Many achievements of Russian glassmaking are associated with the discovery of colored glass. The recipe was developed by M.V. Lomonosov at the Ust-Ruditsk factory, and then this technology spread to all factories in Russia. By the end of the 18th century, ruby, blue, violet, green, turquoise, marble and milk glass were in fashion. For painting, oxides of various metals were mainly used. Ruby glass, which had shades from delicate pink to scarlet, was especially valued. Gold was added to its composition for coloring. Products made from colored glass were painted with gold and silver.

In the 18th century, milk glass, which externally resembles porcelain and, in essence, imitates it, was also considered a variety of colored glass. Sometimes milk glass was dense, “thick,” but more often translucent glass was produced, having a soft, luminous surface. This gave a special luminosity to the polychromy of the enamel painting with which it was decorated. The heyday of artistic glassmaking in Russia occurred in the first third of the 19th century. Newly invented colorless lead crystal appeared, which had a special brilliance, transparency and hardness.

Thick-walled vessels began to be decorated with deep carvings. The different geometric shapes were reminiscent of the processing of precious stones. Hence the name - diamond edge. Crystal products were distinguished by their solemnity and monumentality. At this time, the Imperial Factory in St. Petersburg produced large vases framed in gilded bronze, floor lamps several meters high, and chandeliers for decorating the capital's palaces.

Glass appeared painted with transparent enamels (as opposed to the opaque enamels of the 18th century). Various household items:

Bottles, glasses, ink utensils, decanters;

Decorated with carvings and gilding, thanks to the translucent delicate painting with enamels, they acquired a charming, intimate character.

Curious are the products decorated with printed designs - portraits of members of the royal family, scenes of historical, mythological, and literary subjects. A similar technique subsequently became widely used in the production of mass products.

Products made of two, and sometimes three-layer glass of various colors were processed by grinding, removing one layer at a time. A multi-colored ornament appeared on the surface.

Even in the 19th century, the Imperial Factory produced large, technically complex works that required high skill from glassblowers and decorative artists. A typical example is a dark green vase, consisting of two parts held together by a rod. Gold painting in the neo-Greek style fashionable at that time.

In the second half of the 19th century, some factories producing highly artistic products reduced production as unprofitable. Enterprises that produce cheaper, mass-produced products succeed. These are primarily the Dyatkovo and Gus Khrustalny factories, as well as the Maltsov factories.

The color plate shows only a few examples of glassware made by Russian craftsmen.

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History of glass in architecture and methods of its production

“The history of architecture is the history of the struggle for windows,” said the great architect and designer Le Corbusier in 1929. Therefore, it is clear what a huge significance the invention of glass and its subsequent use in construction had.

Glass was already known in the 9th century BC. e. The center of glassmaking at that time was Alexandria.

Speaking about the history of the use of glass in construction, we will talk mainly about the blowing method and the processes that follow it.

Glass of ancient Rome

The Roman conquest of Judea in 63 paved the way for glass to reach Rome. The Romans were the first to use glass in construction.

Before the invention of glass, thin horn plates, mica, bull's bladders, oiled paper, etc. were inserted into windows, and in some places they were simply left open. These window glass substitutes could be found among the poor until the mid-19th century.

A revolution in the glassmaking process was made by the discovery of the glass blowing method, which made it possible to further process glass. The glass blowing method made it possible, in subsequent processes, to unfold the glass into a sheet and thus obtain sheet glass, window glass.

The Roman Lactantius first mentioned window glass at the end of the 3rd century. It is believed that the blowing method was proposed by Syrian craftsmen who lived in Babylon. This happened between 27 BC and 14 AD. For blowing, they used a thin metal tube, which has remained virtually unchanged to this day.

In Alexandria, around 100 AD, they found a way to produce transparent glass by adding manganese oxide to it.

With the production of transparent glass, the first glass windows appeared. And although at that time they had poor optical properties, they were considered a sign of luxury. Cicero said: “Poor is he whose home is not decorated with glass.”

Archaeological excavations have shown that the first truly flat glass, and therefore the first glass windows, first began to appear in the most important buildings of Rome and the most luxurious villas of Herculaneum and Pompeii.

In museums in Italy, glass from Roman houses measuring 30*30 cm has been preserved, and in Pompeii, during excavations of a bathhouse, a window with a bronze frame was inserted into which frosted glass measuring 100*70 cm and 13 mm thick was inserted.

Ancient Roman glass was of very poor quality. It was either matte or tinted greenish and contained a large number of bubbles. This color was given to the glass by the impurities that were part of its composition.

However, despite the poor quality, this was the first purposeful use of glass in architecture. We can say that from that time on, glass associated itself with architecture and construction forever. And this connection gave a significant acceleration to the development of glass production.

Glass of Western Europe

With the collapse of the Western Roman Empire (476) and the emergence of barbarian German states on its ruins, glassmaking in Europe fell into decline. However, it is restored and receives serious development with the emergence of the Venetian Republic (607).

On the island of Torcello in the Venetian Lagoon, the remains of a glass workshop remain. Mosaic glass and simple vessels, mainly cups and bottles, were made here.

Glassblowing workshops immediately appeared in Venice and by the 9th century it successfully began to compete with Byzantium. Although, as you know, Venetian craftsmen developed their own secrets of glass compositions and methods. The Venetian mosaics and stained glass windows that decorate churches in Venice itself and throughout Northern Italy are well known.

After the capture of Constantinople by the Crusaders (1204), Venice remained the only world center of glassmaking.

In 1330, the Frenchman Cockeray found a way to produce flat glass. The hot glass melt was taken onto the tip of a special tube and spun until a glass “pancake” was obtained. “Damn” was then cut off to the right size and received window glass.

The method for producing such glass was called “lunar” - because of the shape of the resulting pancake. But this method had many disadvantages, the main ones being the large waste of glass when cutting and the presence of a tubercle from the glass blowing tube in the center of the glass.

Sometimes, when using “moon” glass of small diameter, the lead sashes of the window were made round. This reduced glass waste and made it cheaper. But still, the cost of glass windows was very high. Therefore, the “lunar method” was supplanted by the so-called “holyavny” method, which made it possible to produce flat window glass of good quality.

There are cases when glass was inserted into the windows only during the arrival of the owners of the castles. After the owners left, they were taken out.

“Holyava” is a long glass cylinder that was blown by a glassmaker. It could reach 3 meters in length and up to 45 cm in width. Then the top and bottom of the cylinder (while hot) were cut off, the cylinder itself was cut to length and laid on a flat slab, which was placed in the oven. There the glass sheet was leveled. A hot iron rod was used to cut glass.

Diamond was only used for cutting glass in the sixteenth century.

In medieval Western Europe The Gothic era saw the heyday of the production of stained glass windows, where colored glass was already used.

Later, window glass began to be produced in industrial scale, but the technology for its production remained old - “holy”. Window glass was made using this technology almost until the end of the 19th century.

At the beginning of the 20th century, glass began to be produced in glass factories. The principle remained the same - glass was melted in furnaces and then blown. But now the “freebie” was blown out by a machine of a larger size. The glass was then “pulled” out of the furnace using rollers. This method was called “vertical hood”. A serious drawback of this technology was the high cost of glass.

Glass production methods

There are many ways to obtain glass:

Blow method(hand and machine blowing). This is the oldest method of producing glass.

Pull method. A wide continuous ribbon of glass is drawn from the molten glass mass. The vertical pull method has been used since 1914. And it is suitable for the production of glass with a thickness of 0.5 mm.

Libby-Owen method(vertical-horizontal). It involves pulling out a glass tape vertically and laying this tape on the horizontal part of the conveyor belt. Suitable for the production of glass up to 30 mm thick.

Method of forming sheet glass on a melt surface ( float method). The glass melt flows from the melting pool into a bath of molten tin. The density of tin is three times greater than the density of glass, so the glass melt floats to the surface of the bath as a flat glass ribbon with a uniform thickness of 1.5 to 12 mm. The important thing is that glass obtained by this method does not require polishing or grinding and has smooth edges. Nowadays, most glass and mirrors are produced using this method.

Pressing method. A measured amount of glass melt is placed in a glass mold and pressed. Used for the manufacture of hollow blocks, glass tiles, glass facing slabs.

Casting and rolling method. The glass melt is poured onto the casting table and rolled out to the required thickness. This method produces thick glass and glass with ornaments. If wire reinforcement is introduced into the melt, curved glass can be obtained.

Foaming method. Crushed aluminum silicate glass is mixed with crushed carbon, placed in molds and heated to 1,000 degrees. C. Carbon oxidizes and forms bubbles in the melt. This makes the glass sound and waterproof.

Completed by: 11th grade student Maria Serova. "The history of glass in the history of mankind"

Glass is a solid amorphous, transparent in a certain region of the optical range (based on the chemical composition) material obtained by cooling a hot material containing glass-forming components (oxides Si, B, Al, P, etc.) and metal oxides (Li, K , Mg, Pb, etc.). IN modern world The most widespread is silicate glass. Every day we come into contact with this magical material in one way or another, and our life without it is unthinkable. How did it come into being and who invented it?

Glass has been known to people for about 55 centuries. The most ancient samples were discovered in Egypt. Glass items dating back to 2000 BC have been found in India, Korea, and Japan. Excavations indicate that in Rus' they knew the secrets of glass production more than a thousand years ago.

An interesting fact you should know is that glass was not invented by humanity. Glass was born by nature itself. The first lumps of glass appeared from hot lava that spilled onto the surface hundreds of millions of years ago. It is known that it was not transparent, but ordinary matte - almost black. Definition of glass masses - Volcanic glass is now called obsidian.

Some consider glass to be a by-product of copper smelting. And the ancient Roman historian Pliny the Elder (79 - 23 BC) wrote that we owe glass to the Phoenician sea merchants, who, while preparing food in the parking lots, made fires on the coastal sand and propped up the pots with pieces of lime, thereby creating the conditions for the formation of glass melt. Indeed, the starting materials for making glass were quartz sand, lime and alkali - organic (plant ash) or inorganic (soda). Metallurgical slags were used as dyes: compounds of copper, cobalt and manganese. quartz sand soda lime plant ash It is believed that man-made glass was discovered by accident, as a by-product of other crafts. In those days, clay products were fired in ordinary pits dug in the sand, and straw or reed served as fuel. The ash formed during combustion - that is, alkali - upon high-temperature contact with sand gave a glassy mass.

And glass making has been known since ancient times in Egypt. Glass beads and amulets have been found in tombs dating back to 7000 BC. e. Around 1500 BC e. The Egyptians were already making their own glass. To do this, they used a mixture of crushed quartz pebbles and sand. They also discovered that if they added cobalt, copper or manganese to this mixture, they could produce blue, green and purple colored glass. After 1200 BC. e. The Egyptians learned to cast glass in glass molds. But the glass blowing tube was unknown until the beginning of the Christian era, when it was invented by the Phoenicians. In some countries of the world, such tubes are still used in glassblowing workshops.

The Romans were great craftsmen in glass making, and they were the first to make thin window glass.

Venice became famous for its artistic glassware. Venetian glass has extraordinary hardness and amazes with its lightness, grace and beauty.

In the 13th century, numerous glass factories moved from Venice to the neighboring island of Murano, due to frequent fires caused by the round-the-clock operation of glass furnaces. Italian Murano is still a center for the manufacture of handmade glass pieces.

In the 16th century, glass was already being produced throughout Europe. Currently, Bohemian glass produced in the Czech Republic is widely known for its beauty.

Thanks to the invention of a new method of crystal production by the Englishman George Ravenscroft in 1674, a higher quality composition of glass melt was obtained than that of the Italian masters. Ravenscroft replaced potash with high concentrations of lead oxide and obtained glass with highly reflective properties, which was very amenable to deep cutting and engraving. The main countries producing high-quality crystal tableware made from glass with a high lead content are Sweden, England and Ireland.

The first mention of a Russian glass factory - it was built near Moscow near the village of Dukhanino - dates back to 1635. Later, in 1669, another plant was built with treasury funds in the village of Izmailovo. Glass production received especially great development in the era of Peter I (early 18th century), who created an exemplary factory-school on the Sparrow Hills in Moscow. Of greater artistic interest are the glass in the windows of Russian churches of the 16th and 17th centuries, painted with fireproof, indelible transparent paints. It was only at the end of the 19th century that glassmaking began to grow from artisanal into mass industrial production and became an object of everyday life.

Long before today, glass making was considered a labor-intensive process, similar to creating a work of art. For this reason, its price was very high. During the reign of Tiberius, one of the masters created unbreakable glass, however, by order of the emperor, he was executed, since this discovery could cause a sharp decline in the value of glass.

Today everything has changed, and scientists working in this field are striving to make glass as cheap as possible.

Archaeological finds indicate that the first glass was made in the Middle East around 3000 BC. In the beginning, glass production was slow and expensive. In ancient times, glass was a luxury item that only a few could afford.

The oldest glass objects are beads and pendants, created in the pre-dynastic era in Ancient Egypt. The Egyptians also knew glass mosaics. Multi-colored glass plates were heated until they fused, and then stretched to produce thin and very long strips, often depicting simply hieroglyphs. These works were distinguished by amazing care in their execution, but at the same time, the Egyptians never sought to achieve the transparency of glass.

Glass items dating back to 2000 BC have been found in India, Korea, and Japan. Excavations indicate that in Rus' they knew the secrets of glass production more than a thousand years ago.

It is believed that man-made glass was discovered by accident, as a by-product of other crafts. In those days, clay products were fired in ordinary pits dug in the sand, and straw or reed served as fuel. The ash formed during combustion - that is, alkali - upon high-temperature contact with sand gave a glassy mass.

Some consider glass to be a by-product of copper smelting. And the ancient Roman historian Pliny the Elder (79 - 23 BC) wrote that we owe glass to the Phoenician sea merchants, who, while preparing food in the parking lots, made fires on the coastal sand and propped up the pots with pieces of lime, thereby creating the conditions for the formation of glass melt.

Indeed, the starting materials for making glass were sand, lime and alkali - organic (plant ash) or inorganic (soda). Metallurgical slags were used as dyes: compounds of copper, cobalt and manganese.

Today, the main raw material for glass production is calcium dioxide - SiO2, which is white quartz sand. Its main advantage, compared to other substances, is that calcium dioxide can pass from a molten state to a solid state, bypassing the process of crystal formation. This makes it possible to use it to create various types glass Quartz has excessive high temperature melting, so every glass workshop produces glass containing 50-80% SiO2. To lower the melting point, various auxiliary substances are added to the glass mass: lime, sodium oxide, alumina.

In the last century BC. e. Glassmaking developed intensively in the Roman Empire. Clear political and economic organization, rapid construction, extensive trade connections - all this created conditions for the prosperity of the glass industry in Rome's possessions in the Mediterranean and Western Europe. During the time of Emperor Augustus, glass products were exported to France, Germany and Switzerland. It was the Romans who were the first to use glass for architectural purposes - especially after the discovery of transparent glass by introducing manganese oxide into the glass mass, which happened around 100 AD. BC e. in Alexandria. Alexandria at that time was also a center for the production of glass products. The world famous Portland Vase (made of double-layered opaque glass) is perhaps the most famous masterpiece of the Alexandrian masters.

In the Middle Ages, after the collapse of the Roman Empire, the transfer of technology and the secrets of glassblowing skills slowed down greatly, so Eastern and Western glassware gradually acquired more and more individual differences. Alexandria remained the center of glass production in the East, where elegant glassware was made.

By the end of the first millennium, glass production methods in Europe had changed significantly. First of all, this affected the composition of raw materials for production. Given the difficulties in delivering such a component of the mixture as soda, it was replaced with potash obtained by burning wood. Therefore, glass made north of the Alps began to differ from products made in Mediterranean countries, such as Italy.

In the 11th century, German craftsmen, and in the 13th century, Italian masters mastered the production of sheet glass. They first blew a hollow cylinder, then cut off the bottom, cut it and rolled it into a rectangular sheet. The quality of such a sheet was low, but it almost completely replicated the chemical composition of modern window glass. These glasses were used to glass the windows of churches and castles of noble nobles. The same period also saw the heyday of the manufacture of stained glass windows, in which pieces of colored glass were used.

At the end of the Middle Ages, Venice became the center of European glassmaking. During that historical period, the Venetian merchant navy plied the waters of the entire Mediterranean, which contributed to the rapid transfer of the latest technologies (especially from the East) to the fertile Venetian land. Production glass products was the most important craft in Venice, as evidenced by the number of glassblowers in this city - more than 8,000 people. In 1271, a special decree was issued that legitimized some protectionist measures to protect the interests of glassmaking, prohibiting the import of foreign glass, the employment of foreign craftsmen and the export abroad of raw materials for glass production.

At the end of the 13th century, there were already more than a thousand glass furnaces in Venice. However, frequent fires caused by their 24-hour operation forced the city authorities to move production to the nearby island of Murano.

This measure also provided some guarantees regarding maintaining the secret of the production of Venetian glass, since the craftsmen did not have the right to leave the territory of the island.
In the second half of the 15th century, glassmakers from the island of Murano developed new technology obtaining especially transparent glass, which used quartz sand and potash made from seaweed. By the end of the 16th century, 3,000 of the island's population of 7,000 were involved in glass production.

In the 17th century, leadership in the development of glass production technology gradually passed to English craftsmen, in particular, thanks to the invention of a new method of producing crystal by George Ravencroft in 1674. He managed to obtain a higher quality composition of glass melt than the Italian masters. Ravencroft replaced potash with highly concentrated lead oxide and obtained glass with highly reflective properties, which was very amenable to deep cutting and engraving.

France also did not stand aside from the development of glass production. In 1688, a new process for the production of mirror glass was established in Paris, the optical qualities of which until that time left much to be desired. The molten glass was poured onto a special table and rolled out to a flat state. Then a multi-stage process of polishing the surface began, first with rough cast-iron discs, then with abrasive sand of different fractions, and finally with felt discs. The result was a mirror surface with unprecedented optical properties. From such glass coated with reverse side layer of silver, high-quality mirrors were obtained. The French lured away capable Venetian craftsmen with good professional skills and who know the secrets skill. The French authorities offered Venetian craftsmen many incentives: for example, French citizenship after eight years of work and almost complete tax exemption.

But it was only at the end of the 19th century that glassmaking began to develop from handicraft into mass industrial production. One of the “fathers” of modern glass production can be called the German scientist Otto Schott (1851 - 1935), who actively used scientific methods to study the influence of various chemical elements on the optical and thermal properties of glass. In the field of studying the optical properties of glass, Schott teamed up with Ernst Abby (1840 - 1905), a professor from Jena and co-owner of the company of Carl Zeiss. Another significant figure who contributed to mass production glass, was Friedrich Simmens. He invented a new furnace that made it possible to continuously produce much larger quantities of glass melt than previously.

At the end of the 19th century, American engineer Michael Owens (1859–1923) invented automatic car for bottle production. By 1920, approximately 200 Owens machines were operating in the United States. Soon such machines became widespread in Europe. In 1905, the Belgian Fourcaud made another revolution in the glass industry. He invented a method of vertically drawing a glass sheet of constant width from a furnace. In 1914, his method was improved by another Belgian, Emile Bicherois, who proposed stretching the glass sheet between two rollers, which greatly simplified the process of further glass processing.

In America, a similar process of drawing glass sheets was developed somewhat later. The technology was then improved with the support of American company Libbey-Owens and began being used for commercial production in 1917. The float method was developed in 1959 by Pilkington. In this process, glass flows from the melting furnace in a horizontal plane in the form of a flat strip through a bath of molten tin for further cooling and annealing.

The advantages of this method compared to all previous ones are stable glass thickness, high quality glass surfaces that do not require further polishing, no optical defects in the glass, high performance process. The largest size of the resulting glass is usually 6 by 3.21 m, and the sheet thickness can be from 2 to 25 mm.

Currently, the world produces about 16,500 million tons of flat glass per year. What does the glass making process look like today? Before an elegant mirror, a beautiful vase or light glass furniture appears from a set of chemical elements, these substances must undergo a series of procedures. When creating glass or a mirror, first of all, in huge baths that hold up to a thousand tons of glass, substances that have low temperature melting. Then quartz sand is added there, which successfully melts at a temperature of 1000 degrees. But this process cannot be considered complete: it is necessary to degas the resulting glass mass. To do this, it is heated in special regeneration furnaces to a temperature of 1400-1600 degrees. As they rise to the surface, the gases promote uniform mixing of the glass.

The glass furnace operates continuously. On the one hand, ingredients are supplied there, as a result of mixing which glass will be created. Gradually they turn into molten glass and subsequently enter a special conveyor where the glass is cooled and cut into sheets of the required size. In order to create not ordinary glass, but a mirror, craftsmen, while moving frozen glass along a conveyor belt, first coat it with a thin layer of silver, then with a layer of copper and, finally, with varnish. In one minute of such processing it is possible to create a mirror 2.5 meters long, and in a month such a furnace produces a mirror with an area of ​​40,000 square meters. m.