Obsidian, © Vetropack SA
The History of Glass
Obsidian originates in thick lava flows rich in silica. Opaque or slightly translucent, its colour varies from grey to dark green or from red to black. Humans have exploited it since the Neolithic period, around 8000 BC. It was used not only to make weapons and cut tools, but also for jewellery, as it is fairly easy to cut despite its hardness.
Egyptians, Greeks and Romans
Around 4000 BC, perhaps? There is no agreement among scholars about the exact date when man tamed the material of glass. Pliny the Elder recounts the legend of its discovery: “There is a story that once a ship belonging to some traders in natural soda landed here [on the banks of the river Le Bélis, in Phoenicia, present-day Lebanon]and that they scattered along the shore to prepare a meal. Since, however, no stones suitable for supporting their cauldrons were forthcoming, they rested them on lumps of soda from their cargo. When these became heated and completely mingled with the sand on the beach a strange translucent liquid flowed forth in streams; and this, it is said, was the origin of glass.” (Pliny the Elder, Natural History, book XXXVI, LXV).
In the Middle Ages
The invention of a metal tube, the “blowpipe”, for blowing out the mass of glass made it possible to produce faster, cheaper and larger glass containers with thinner walls.
The spreading uses of glass
In the 17th and 18th centuries, the use of glass spread to construction and decoration. The discovery of cast glass (a mass of molten glass poured onto a table, transformed into a glass plate by means of a metal roller) made large-scale production possible.
At the end of the 19th century, Thomas Edison discovered how to produce electric light using glass bulbs. The technical developments, advances in chemistry and the progress of thermodynamics of that time open the door to mechanization.
At the beginning of the 20th century, production was industrialized thanks to the manufacturing processes of mechanical rolling and continuous stretching. In 1959, Alastair Pilkington developed the “float process”: at the furnace exit, the melt is poured into a tin bath, where it forms a continuous ribbon of flat glass floating on the surface. The result is very flat, smooth high quality glass. The current means make it possible to create glass of very varied thicknesses (between 0.4 and 25mm).