Float glass is flat glass produced by flowing molten glass over a bath of liquid tin, making it perfectly flat and parallel. This float glass process was developed in 1959 by the British manufacturer Pilkington and has since become the worldwide standard for producing modern flat glass.
Application
In the float glass process, the raw materials (sand, soda, lime and cullet) are melted in a furnace at around 1500 °C. The molten glass then flows onto a bath of liquid tin. Because glass is lighter than tin, it floats on top and spreads out into a perfectly flat layer of uniform thickness. Since both the tin surface and the top surface of the glass are smooth, two perfectly parallel, mirror-smooth faces are formed.
The glass ribbon then moves into the annealing lehr, where it cools in a controlled, stress-free manner. Finally, the ribbon is cut to size.
Characteristics
The advantages of float glass are considerable: exceptional flatness, high clarity and optical purity without distortion, and the ability to produce very large formats at constant thickness. This makes float glass the base product for virtually all modern glass applications, from glazing to mirrors, and the raw material for processed glass such as toughened, laminated and insulating glass.
Related terms
- glass
- building glass
- double glazing
- glass construction
- curtain wall
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