It is not possible to assign a precise year to the birth of glass since it is a naturally occurring material. In fact, when quartz sand melts at high temperatures, once cooled it turns into a solid mass: glass. Such situations easily occur near volcanoes.
The first people who took credit for inventing a glass-making technique are artisans in Mesopotamia. In fact, the first “recip” for making glass was written by Assyrian King Ashurbanipal and consisted of “60 parts sand, 180 parts dried seaweed powder and 5 parts chalk.” At that time glass was used exclusively for making jewelry and necklaces.
In about 100 B.C. a glass craftsman on the Syrian coast invented the blowpipe: a tube with a mouthpiece for blowing glass. Thanks to this tool, various glass materials with reduced thickness are produced.
The first people to use glass as door closures in their homes, and thus as primordial windows, are the Romans.
Having discovered the usefulness of glass in window making, new techniques for producing this material became increasingly widespread.
Initially the most common was the casting of molten glass into molds. The Romans in England, between 43 and 40 A.D., made up window panes using small pieces of glass, as if they were slabs of pebbles laid on a wooden frame.
In the agricultural townships of Pompeii, windows garnished with glass were not numerous and, most of the time, consisted of small frameless glass “disks” simply walled in with the rim. But in the important cities, and particularly in Rome and the opulent patrician villas of the Latium area, numerous examples of large openings closed with glass panes were already seen then.
Regarding this, Cicero’s sentence in the second half of the first century must be reminded: “it must be considered very poor the one whose apartments are not decorated with glass,” from which it is clear that the prestige of glass in Roman society at the time was truly astonishing.
Under Nero (37-68 A.D.), the first Roman glass workshop was built – very well equipped – while already in the year 220 the furnaces were so numerous as to make the air of the Urbe mephitic, obliging the administration to assign a special sector of the peri-urban territory to the glassmakers for their installations.
Around 100 A.D., the technique of glassblowing was further developed in Alexandria. Artisans would blow until the glass bubbles took on the appearance of a hollow “crown.”
Flat discoidal sheets were obtained, which were then joined with lead to form larger surfaces. Initially, the result allowed no visibility, so in later periods methods evolved to the production of thinner, more transparent rectangular panels.
In the 13th century, the art of glassmaking developed in Venice, particularly on the island of Murano, thanks to contacts between the merchants of the Serenissima and the East, later becoming a point of reference for glass production.
Furthermore, in 1271 the Statute of Venice protected Venetian glassmaking, prohibiting the import of glass from abroad and denying foreign glassmakers the opportunity to operate in Venice.
In the 16th century, glass was considered a luxury good, so much so that in the homes of the upper classes, glass in windows was found only in the most important rooms.
Different ranges also began to spread in the following century, including the casement window characterized by an inward opening that allowed the glass, still considered a precious and delicate material, to be protected.
At the end of the century, the French developed a new technique to produce larger and clearer glass dishes. By pouring molten glass onto a table it was then worked with a fine roller to achieve a uniform thickness.
Following the Industrial Revolution finally a machine was invented that made mass production possible, the continuous basin furnace.
In 1851, while engineers from different countries competed in creating the largest and strongest window, two unpopular late 17th-century window and glass laws that had led to the closing of many holes in buildings were repealed in England.
That same year, to host the first World’s Fair, the Crystal Palace, a huge, steel-framed, 39-meter-high, Victorian-style building with 92,000 square meters of floor area, completely covered with glass panes, was built in Hyde Park in central London. The Crystal Palace will be destroyed by fire in 1936.
In 1913 the Fourcault process for making pulled glass was developed, followed in 1916 by the Libbey-Owens method and in 1925 by the Pittsburg method, in order to obtain sheets of increasing size, free of optical defects.
Further progress occurred in 1925 when engineers Ingle and Smith patented the IS machine for making hollow glass.
Through the blowing method, the drop is first blown into a metal preform, then transferred to a second mold where it is shaped by blowing until it takes its final shape.
A few years later the first glass fibers are made, about 1928.
Currently, 90 percent of the flat glass produced in the world is manufactured using the “float” system, invented by Alastair Pilkington, where molten glass is poured at one end of a bath of molten tin. Hence the name “float glass.”
As the liquid glass floats, it spreads along the surface of the bath, creating a smooth surface on both sides. The glass cools and solidifies as it flows down the bath, forming a continuous ribbon.
Once it is divided into sheets, it is then heated again on both sides (fire polishing) to make two perfectly parallel surfaces.