Double-glazed windows have become such a part of our reality that we have come to consider their presence a completely natural phenomenon. We don't ask ourselves where they came from, what buildings looked like before glass, or what they looked like before windows were even glazed.
However, these questions are worth getting answers to because the history of glass is fascinating and longer than you think, and glazed window openings did not always look like modern ones.
Ancient glass bowl
When did glass appear?
The history of glass goes back about 5,000 years. The first finds indicating that glass was already being smelted date back to this period. It is likely that the glass appeared as a result of the melting of sand during forest fires or a lightning strike. However, 5000 years ago people began to imitate this natural process. Over time, the first simple and imperfect glass manufacturing technologies appeared.
At first these were small, randomly colored, opaque items used as decoration. Over time, people learned to discolor glass and give it the desired shape, and then the production of glass vessels began. The properties of glass make the study of its history complex, largely dependent on chance archaeological discoveries and providing answers to only a few questions.
The first glass vessels
Glass is a fragile material . Therefore, relatively few of the most ancient objects have survived to this day, preserved enough that their original appearance can be reconstructed. On the other hand, glass is resistant even to aggressive chemical compounds and does not rust, so even after thousands of years it is possible to reconstruct the production process based on the chemical composition of the sample.
Middle Ages and Renaissance
Dark and beautiful gothic stained glass window
In the Middle Ages, the so-called Romanesque style prevailed. Due to constant wars, each house (especially those belonging to a rich person) was a small fortress, the windows of which served exclusively as loopholes. Therefore, there was no time to think about beauty.
However, quite soon the Romanesque style was replaced by the Gothic style, and here windows began to be used for decoration. Painted stained glass windows with religious themes and large window openings became characteristic features of this style.
The Renaissance (also known as the Renaissance) exalts antiquity and man, which is why religion begins to play a much less important role in the life of society. Because of this, the windows become transparent and religious scenes disappear from them. Materials have become more accessible and cheaper. Thanks to this, windows are spreading all over the world.
Why do we need glass in windows?
The question, at first glance, is meaningless. Why at some point was it decided that glass could be framed and placed in a window frame? Undoubtedly, this was due to two properties: light transmission and heat retention in the room.
Previously, window openings were closed before winter or not closed at all. Inside buildings and tents, the only sources of light were small holes in the ceilings and walls, fires and torches.
Window glass began to be used around 100 AD. At first the glass was opaque, so you couldn't look out the window without opening it, but it let in enough light to illuminate the room during the day without cooling it down.
Initially, this invention was available only to rich people . The production process was labor-intensive, long, and only a few craftsmen could master it. High demand and low supply have made window glass a luxury item.
Window architecture in painting
The twentieth century wrote the brightest pages in the history of windows. Read about this period, the leading developers, the most important technologies, and innovative solutions that increased the functionality and aesthetics of the window opening in the article: The twentieth century is a time of new breakthroughs in window technologies.
Artists of all times and peoples have devoted many paintings to the theme of windows, reflecting changes in window structures under the spirit of time. The list of names of artistic celebrities who came into contact with the topic of historical types of windows is endless: Rembrandt, Raphael, Picasso, Vorovsky, Tropinin, Caspar Friedrich, Redonto, Salentine, O'Brien, Lady of Shalott, Geoffrey. Blaas, Sredin and many others.
Photo: the famous “Morning” (1954) by Tatiana Yablonskaya is stored in the State Tretyakov Gallery, © https://twitter.com/DSvatkovsky
The OKNA MEDIA portal thanks the creators of the art gallery on the theme: “Windows through the eyes of an artist.”
How was the first glass made?
In Russia, window glass was certainly produced already in the 13th century. It was produced in the form of small round containers resembling plates. This shape is the result of the glass blowing method used.
A drop of plasticized material was placed at the end of a metal tube and blown into a hollow sphere, which was then quickly rotated to form a round “cake” several centimeters or more in diameter. At the end it was cut into two parts at the edges. Next, the resulting products were connected with lead frames and framed in wooden window frames.
Photo : During excavations as part of the Jezreel Valley Railroad project, the remains of the oldest kiln kilns (1,600 years old) in Israel, which produced glass on an industrial scale, were discovered between the HaEmakim and Yagur interchanges.
Since the 14th century, a method for producing glass for windows, developed in France, has been known. The process began traditionally, with the blowing of a drop of glass, but at some point the tibia (blowing tube) was set in motion. Under the influence of centrifugal force, a round sheet with a diameter of about one meter was obtained, from which the necessary, usually correct, shapes could be cut.
The process of blowing a cylinder of liquid glass
Another method of making glass involves blowing a cylinder, cutting it lengthwise, and rolling the resulting sheet onto a flat surface.
The sheets produced in this way were small in size and had an uneven surface, which must have distorted the image created by the transmitted light. Only at the beginning of the 20th century was mass production of flat sheets established, the affordable price of which allowed them to be widely used. The first large-scale technological process was developed in 1913 by the Belgian engineer Emile Fourcauld .
Since then, a lot has changed in the production of window glass, but this is a topic for another story.
Ancient technologies
The history of glass in human history goes back more than 4 thousand years. Images and artifacts found in the tombs of the pharaohs provide insight into the ancient production methods and taste preferences of the Egyptians. Thus, glass was originally used as a glaze for pottery. It was also used to make beads, bottles and pendants.
The Egyptians, unlike the inhabitants of Mesopotamia, preferred opaque glass. It was colored with metal oxides in blue, violet, yellow and other colors. Only officials and persons of royal blood could afford glass products. Small objects were made using the following method: a clay core was placed on a metal rod, onto which hot glass was wound.
Large ones were made like this: the mold was placed in a glass mass and turned. The glass settled in a thin layer on the walls and hardened, and the mold was subsequently removed.
Who makes glass?
Glass is a complex material: fragile by nature, susceptible to damage, requiring very delicate handling. More durable products made from tempered or thick glass are even less convenient to work with. Add to this the fact that glass used to be a relatively expensive material, and it becomes easy to understand why glassmakers have always been considered artisans - artists of the highest rank .
Workshop of Venetian glassblowers, 18th century.
Glass needs to be felt. A glassmaker must be skillful, courageous, confident in himself, his knowledge and experience. The glazier must know, or rather instinctively feel, where to cut or drill the sheet, and how much force to apply to achieve the desired effect. Large glasses are very demanding: they are heavy, full of internal tension. They are difficult to handle, move, manipulate and assemble.
Compared to other professions, a glassblower's tool kit is not very extensive. Dry and oil knife, compass, rulers and protractors, drills, tearing pliers, handles for working with sheets, sanding materials. Art glass is made using a kiln and several traditional tools: a blow tube, tongs, and other shaping tools.
The simplicity of this equipment can be misleading if one assumes that the art of melting and shaping glass is equally uncomplicated.
Antique vases
Window architecture - from antiquity to the present day
From a historical point of view, the first window was a chimney. By the way, in Russia there is still evidence of the existence of this period in the history of windows - baths that are heated in black.
To create draft for the fire, a hole was made in the ceiling under the heater. After the bathhouse reached the desired temperature and the fire burned out, it was plugged with a rag. The smoke escaped both through this hole and through the door. This hole cannot be called a window in the literal sense, but as a means of ventilation, yes.
Photo: the only source of natural light in the black-heated baths was a small blind window, © par-torg.com For some peoples, the window opening was combined with the entrance area. This fact was captured by Herodotus in the “History” in the part in which he describes the Riphean Mountains (the ancient name of the Ural Mountains).
By the way, even today plastic window-door construction can be seen among some peoples of the Far North - Khanty, Mansi, Nenets and some others. In its external features, it resembles a hole, which you can squeeze through only by getting on all fours.
Photo: but more often the Nenets tent has neither a door nor a window in the usual sense of these words. The door is simply a canopy of skin, and the window is an opening for the skins that cover the structure of poles, © borealis-voyages.com It is covered with stretched deer or bear skin. In winter, when snow covers the home to the very roof, residents dig passages leading from house to house.
It was this unusual method of movement under the snow that attracted the attention of the ancient Greek historian. An interesting fact is that even in such exotic designs as window-chimney and window-door, a system for protecting the room from the influence of external factors was thought out.
It was the desire to protect the home from wind, cold, sun, rain, noise that determined all further improvements in window design. With the development of civilization, man mastered the production of glass and metal, wood processing and leather dressing.
Photo: if you step over millennia, you can see the baths in Pompeii - the first building in the history of world architecture, in the windows of which (size 0.9 x 1.2 m) glass was installed, © gazzettadinapoli.it It was this type of window that was called “ Mediterranean." Windows of this kind can be seen in Spain, Greece, Bulgaria and other countries.
Photo: in the northern countries, to this day you can see such enclosing structures that appeared at the end of the 7th century and were called “fence windows”, © astapro.ru Such a window included: a window frame (window frame), a frame set into it for the winter ( glass, bull's bladder or peritoneum), portage (a sliding shutter located on the side of the room), window inserts (slopes) and shutters. They protected the window (window opening).
Thus, wooden windows were created for the first time, the design principle of which remains unchanged to this day.
In the Middle Ages, “Venetian” windows and “French” windows and balconies appeared.
Photo: double windows, divided by a column or pilaster into two symmetrical parts, which are united by a common arch or triangular pediment, first appeared on the houses of Venice in the 15th century, © extrip.ru It received the name “biforium” from the Latin word biforium (double, two-sided) . Later, during the Renaissance, when biforia, richly decorated with stained glass, became popular throughout Europe, they were called “Venetian” windows after the birthplace of the architects who first installed them.
The accumulation of construction experience allowed architects to change the height of the building and the proportions of the buildings. If at the end of the 15th century the highest vaults were the Senlis Cathedral (17 m), then in the 16th century the construction of the cathedral in Beauvais began with vaults 48 m high.
Photo: by the way, this building was repeatedly destroyed precisely because of its excessive height, but to this day, French architects continue to constantly maintain the integrity of the composition of the cathedral, constantly reconstructing these gigantic structures, © turbina.ru Experiments were carried out not only in height, but also in width. Window openings occupied more and more of the wall surface. Almost completely abandoning simple rectangular shapes, French architects turned window structures into real works of art: the lace of stone frames - at the same time the strength elements of the window - harmonized with the huge stained glass windows.
The basis for creating window compositions was the principle of repeated repetition of a two-part Venetian window, but improved and elevated by the masters to the rank of an artistic technique.
Photo: the windows of the Notre Dame Cathedral in Reims (France), called “French”, became the architectural pinnacle, © funart.pro Today, any structure whose light opening is larger than usual is called French.
In Russia, large windows were not in demand until the mid-19th century. The situation changed with the invention of a water heating system by a German-born Russian engineer, Franz Friedrich Wilhelm San Galli (1824-1908). Warmth became available.
Photo: in order to clearly demonstrate this, the author built it at his own expense in the 1870s. on Petrovsky Island “Colonia San Galli” - several houses furnished according to his system, intended for rent, © ru.m.wikipedia.org The houses very quickly became fashionable and prestigious apartments. Thus, this experiment proved that even in a northern country with a harsh climate, it is possible to install windows with a large light opening if the heating and ventilation system is thought out.
Photo: modern heating and ventilation systems in tandem with innovative materials have led to the fact that a modern window can easily replace a wall, © castellancapital.com
Relay race of generations of glaziers
Knowledge about glass, before it was formalized and based on scientific and technical research, was the sum of experience, trials, failures and successes. The process of accumulating knowledge took hundreds of years. It was passed down from generation to generation and carefully protected from competition. In many centers, glassmakers' guilds (the first such guild was created in Venice in the 13th century) accepted as apprentices only those candidates whose fathers were also glassmakers .
The best masters possessed and were able to use many talents: spatial imagination, a sense of proportion, the ability to perform mathematical calculations and at the same time manipulate light in such a way as to achieve the effect intended by the architect or designer.
In Europe, the largest glass production centers were created in Germany, France, Scandinavia, Italy and England. Venetian and English glass, in particular, was famous for its high quality and unique optical properties. The Venetian Barovier family has been carefully preserving the tradition of glass smelting and the production of glass products for about 600 years. It is difficult to find a family with similar traditions, regardless of the type of craft.
Glass in Rus'. Craft development
The glass came to us from Byzantium. Carrying out excavations in the Kiev-Pechersk Lavra, archaeologists found glass workshops dating back to the 11th century. Of course, not many products have survived and most of the secrets of the craft have been lost. Therefore, it is difficult to guess what exactly the history of glass in Russia was and whether it existed at all.
World history has repeatedly confirmed that humanity had to reinvent some things. The revival of glassmaking took place in the 17th century, namely in 1639, when a master from Sweden, Y. Koyet, built a factory near St. Petersburg that produced glass for windows and apothecary bottles; 30 years later the Izmailovo factory opened. Only expensive products were made there, the prototype of which were Venetian masterpieces.
In the 18th century, several glass factories were already operating in the vicinity of St. Petersburg. A new technology for producing colored glass was developed. The products were finished in silver and gold, and also decorated with various types of enamels.
Secrets of glass production in the past
Glassblowers and glaziers were surrounded by an aura of mystery, but restrictions on the profession were not equally strict everywhere. In some regions, such as 16th-century Lorraine, candidates swore “on the curse of the soul and the loss of paradise” that they would not impart their knowledge to outsiders. In others, they were free to travel, set up glass factories, and seek apprentices.
In France, the glazier profession was literally ennobled. Glassmakers were considered to be among the nobility . In some countries, glass guilds were not created, and glass makers joined other guilds, such as the butchers' guild, which is not easy to explain.
The history of the appearance of glass in Rus'. Development of the craft
This expensive material came to Rus' from Byzantium. In the Kiev Pechersk Lavra, archaeologists have excavated glassmakers' workshops dating back to the 11th century. But few products survived, the secrets of craftsmanship were lost. Therefore, it is difficult to guess whether there was a Russian history of glass. In the history of mankind, it has often happened that many things had to be reinvented. The revival of the craft happened only in the 17th century (in 1639), when the Swede J. Koyet built a factory near the capital for the production of window glass and pharmaceutical glassware. Thirty years later the Izmailovsky plant was created. Luxury goods were made here, mainly exquisite “amusing” goblets modeled on the Venetian ones.
In the 18th century, several glass factories opened in the vicinity of St. Petersburg. Stained glass was reinvented. The items were painted with gold and silver and decorated with transparent and opaque enamels.
Glassmaking today
The Industrial Revolution of the 18th-19th centuries became an important stage in the history of glass. New types of furnaces were developed and technologies changed. Many new factories appeared, the products of which were created for the broad masses, and not for titled persons. Glass has become accessible to everyone. At the beginning of the last century, there were a lot of enterprises in Russia that produced both tableware and sheet glass. But the volume of imports also remained considerable.
In the middle of the century, British specialists developed a method for stretching and leveling glass - for this they used a bath of molten tin. This option is called the “float method”. At the moment, having undergone modernization, this technology continues to be widely used.
Sources
- https://www.wikipro.ru/wiki/istoriya-stekla/
- https://www.vseznaika.org/history/kto-izobryol-steklo-i-gde-eto-proizoshlo/
- https://FB.ru/article/162454/istoriya-stekla-v-istorii-chelovechestva-izobretenie-i-izgotovlenie-stekla
- https://glavsteklotara.ru/nashi-sovetyi/istoriya-stekla.html
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Transition to new methods of window glass production - float process
The credit for creating a revolutionary method of producing polished glass (float process) belongs to Sir Alastair Pilkington
Lionel Alexander Bethin (Alastair) Pilkington was born in 1920, and after leaving school in Sherborne he entered Trinity College, Cambridge, where he received his first degree in mechanical engineering. During the war he left university and joined the Royal Artillery. Participated in hostilities in Greece and Crete. After being released from captivity at the end of the war, he returned to Cambridge to continue his studies and decided to pursue a career as a civil engineer.
In March 1947 he was appointed technical assistant at the Pilkington plate glass factory, and two years later he became production manager at the Doncaster factory. In 1952, Alastair returned to St. Helens, and under his leadership, experimental work began on the development of the float process. As a result of his first experiments, he proposed using a melt of metal to form and transport glass strips.
In 1953, a sample of float glass 300 mm wide was produced at the first pilot plant.
In 1955, a new pilot plant produced 760mm wide float glass, and the Pilkington board made the bold and risky decision to build a 2540mm wide float-line. The company hoped for success, but at the same time understood that if it failed, financial losses would amount to millions of pounds. On the other hand, the successful launch of the line guaranteed a significant and revolutionary leap in flat glass technology throughout the long history of glass production.
The float production line was introduced at Cowley Hill (UK) on May 6, 1957. Many at that time did not believe in the new process, and said that this line would not produce even 1 m² of glass. Only 14 months later, the first high-quality float glass (float-glass) with a thickness of 6.5 mm was obtained, and on January 20, 1959, the Pilkington company officially published a press release in which it introduced the float process in the following words:
"The float process is the most fundamental, revolutionary and important advance in glass production in the 20th century"
In accordance with the float method developed by the Pilkington company, glass melt from the glass pool at a temperature of 1100 ° C is conveyed in a continuous ribbon from the glass furnace to the surface of the molten tin. The tape is kept at a high enough temperature to remove all defects and irregularities on the glass surface. Since the surface of the molten metal is a perfectly smooth surface, the glass acquires a “fire-polished” shiny surface that does not require further grinding and polishing.
During experiments, it was established that the molten glass mass does not spread indefinitely on the surface of molten tin. When the forces of gravity and surface tension are balanced, the tape reaches an equilibrium thickness of about just under 7 mm. To obtain glass strips of various thicknesses, methods were created based on regulating the viscosity of glass in the forming zone and the magnitude of the tensile force. If it is necessary to obtain a glass strip thickness greater than 7 mm, then it is compressed by non-wetting side limiters.
At the beginning of the work, the problem arose of choosing a molten metal, which should be in a liquid state within the temperature range from 600 to 1050 ° C, have low vapor pressure values, and the density value should be higher than glass. Research has shown that tin, which almost does not interact with glass, meets all these requirements and is a completely accessible and cheap product. But tin at high temperatures is oxidized by oxygen to form oxide compounds. Therefore, in order to prevent oxidation of the surface of the tin melt, it is necessary to create an inert atmosphere of nitrogen with a small addition of hydrogen in the float bath. After molding, the glass strip is cooled to 620°C and transported to an annealing furnace.
