MAKING FLAT GLASS (THE FLOAT PROCESS)
The float process of glass manufacture was developed by the Pilkington Glass Group (England) in 1959. There are currently over 60 float glass plants operating around the world, some under licence. In the float process, a continuous ribbon of molten glass moves out of a melting furnace (1 500oC) and floats along the surface of a bath of molten tin.
The ribbon is cooled down while still advancing across the molten tin until the surfaces are hard enough for it to progress through the annealing lehr without the rollers marking its bottom surface. The glass produced has a uniform thickness and bright fire polished surface, without the need for further grinding and polishing.