Page 40 - Curriculum Visions Dynamic Book

Making glass
Float glass is the name given to large flat sheets of glass that are made by floating molten glass on molten tin.
The manufacture of float glass relies
on several unique properties of tin. Tin and glass do not react; tin is denser than glass; and whereas the melting point of
tin (232°C) is far below the melting point of glass (1400°C) the boiling point of tin is well above the melting point of glass. Thus tin can be used as a stable, nonreacting liquid on which to float the glass.
During the continuous formation of flat glass, molten glass is run out over a very shallow bed of molten tin, ensuring that the glass cools as a smooth, flat sheet.
 The traditional method of blowing glass. The almost molten glass is collected on the end of a pipe and a skilled worker blows down the tube and into the molten ball.
Float bath
Furnace tank
Gas heaters
Sand, sodium carbonate, calcium carbonate and recycled glass
Molten glass
Molten glass pours over lip and into float bath
Very shallow layer of molten tin
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