From lightning bolts and ancient Mesopotamia, to the Romans and WW2, glass production has changed a lot.
Natural glass is a material that is formed when rocks melt from high temperature caused by volcanic eruption, lightning or meteorites impacts. One of the earliest man-made glass objects were non-transparent glass beads dated around 3500 BC and were found in Egypt and Mesopotamia.
However it was the Syrians that discovered ways of glassblowing around 27 BC and the Romans who used glass in architecture and were first used clear glass around AD100.
German craftsmen achieved the production of glass sheets by blowing a hollow glass sphere and swinging it allowing gravity to form a cylindrical pod. They then cut the ends of the pod and the cylinder formed is cut lengthways and laid flat to form sheets.
Bullions or crown glass is another type of sheet glass. A glass ball was blown open on the opposite side to the pipe. By spinning the ball, it would flatten and increase in size enough to form sheets. However the technique could only produce a limited diameter.
Flat glass was originally produced by pouring molten glass in tables where it could be rolled into plates and then left to cool. Fourcault, a Belgian craftsman managed in 1905 to make a continuous sheet of glass at a consistent width.
At the end of World War I, Bicheroux, also Belgian, managed to pour molten glass from a pot, into two rollers. This produced glass of a more even thickness making grinding and polishing easier and much more economical than before.
Flat glass production had a breakthrough when lamination was introduced as a method to strengthen glass. Lamination is the procedure when a celluloid layer is inserted between the sheets of glass. The procedure was invented by French craftsman Benedictus, who patented this new safety glass under the name Triplex in 1910.
American Colburn, having help from the US company Libbey-Owens, developed another method for drawing glass for commercial production in 1917. The two methods from Fourcault and Libbey-Owens were further developed by Pennvernon, and the Pittsburgh Plate Company (PPG), which has been used since 1928.
However, it was only after World War II that Britain’s Pilkington Brothers Ltd combined the brilliant finish of sheet glass with the qualities of plate glass. Molten glass is poured across the surface of molten tin spreads and flattened, and is then drawn horizontally in a continuous ribbon.
Although the process of manufacturing float glass remains almost unchanged since the 1950s, the product has been refined to a point where glass can be produced that is less than 1mm thick right up to 25mm thick, with an optical clarity close to perfection. Drawn or historic glass can also still be produced today, which helps window renovation experts like Ventrolla when replacing a small single pane in a larger, Georgian style, window, so it doesn’t look out of place against its historic counterparts.