Float Glass
90% of the world's flat glass is produced by the float glass process invented in the 1950s by Sir Alastair Pilkington of Pilkington Glass, in which molten glass is poured onto one end of a molten tin bath. The glass floats on the tin, and levels out as it spreads along the bath, giving a smooth face to both sides. The glass cools and slowly solidifies as it travels over the molten tin and leaves the tin bath in a continuous ribbon. The glass is then annealed by cooling in an oven called a lehr. The finished product has near-perfect parallel surfaces.
The side of the glass that has been in contact with the tin has a very small amount of the tin embedded in its surface. This quality makes that side of the glass easier to be coated in order to turn it into a mirror, however that side is also softer and easier to scratch.
Glass is produced in standard metric thicknesses of 2, 3, 4, 5, 6, 8, 10, 12, 15, 19 and 22 mm. Molten glass floating on tin in a nitrogen/hydrogen atmosphere will spread out to a thickness of about 6 mm and stop due to surface tension. Thinner glass is made by stretching the glass while it floats on the tin and cools. Similarly, thicker glass is pushed back and not permitted to expand as it cools on the tin.
Read more about this topic: Architectural Glass
Famous quotes containing the words float and/or glass:
“I may be smelly and I may be old,
Rough in my pebbles, reedy in my pools,
But where my fish float by I bless their swimming
And I like the people to bathe in me, especially women.”
—Stevie Smith (1902–1971)
“When God at first made man,
Having a glass of blessings standing by,
“Let us,” said He, “pour on him all we can:
Let the world’s riches, which dispersed lie,
Contract into a span.””
—George Herbert (1593–1633)