`Pilkington float glass process`

Post-WWII development; molten tin bath, 15 ft wide, few inches deep; pull thin glass (⅛" to ¼") off; anneal and cut. Footprint reduced from mile-long PPG building to ~couple hundred yards. Tom toured an Ohio float glass plant; furnace at 1550°C, half a football field.

By probably the 1940s, Pilkington developed their own process called the Pilkington process, which is the float glass process. You have a blending and melting furnace — this is called the batch house — and then the furnace in which you melt it. Let me tell you, I have been through a float glass plant in Ohio, and you're walking by this furnace at 1550°C that's about half the size of a football field, and it's hot. A lot of radiant heat even though it's insulated and everything. They pull it over the weir and then they float it on a bath of molten tin. Not a very deep bath — molten tin probably only a couple of inches deep, but it's probably 15 feet wide. Now you can pull off stuff that's an eighth of an inch thick, three-sixteenths, a quarter of an inch thick. You take that and you anneal it, because glass can have serious problems if it's got residual stresses in it, and you cut it to size and ship it. It's not a mile-long building — might be a couple hundred yards, but it's not a mile.