Glass is made from a mixture of sand, lime and baking soda. These raw materials are heated, making it liquid. Over the years, however, the techniques for producing glass have changed considerably.
Glass has been used for window openings since Roman times, but for a long time the size was very small. Several small panes together often formed one larger window, as in stained glass. Until the early 20th century, however, glass was only reserved for the wealthier people. Making glass was very labor intensive and was done by blowing pipes. From the beginning of the 20th century, the techniques became slightly better, the window surfaces larger and the costs slowly went down.
Around 1920, the Belgian Fourcault developed a new mechanical way to produce glass. Here, a sheet of glass is pulled out of a melting sheet of glass using a slotted beam. This is why this type of glass is also called "pulled glass. Pulled glass does not look as sleek as modern flat glass, as "distortions" are visible. This distorted glass fits very nicely with older monumental buildings, which is why it can be supplied today as monument glass with modern insulation values.
Full-flat glass as we know it today was developed by the company Pilkington. In this process, raw materials are first melted in a furnace to about 1100°C. The mixture is then poured into a shallow bath of molten tin. Here the mixture floats (hence the term "float glass") and spreads evenly. The surface tension of glass and tin are so different that the liquid glass can float on the tin. The temperature of the glass gradually drops from 1100° to 600° Celsius when the glass leaves the tin bath in solid form. It is then automatically cut into the correct size.
Read more about the history of glass on the website of glasspecialisten.nl of the Bouwend Nederland Vakgroep GLAS.
