Nowadays the glass industry has been spoiled with the perfectly-flat glass surface that is taken for granted. However before 1959, when Sir Alaistair Pilkington invented the float glass process, none of this was possible. At the time, other manufacturing processes could not provide a perfectly-flat result.
There are some 260 float-glass plants worldwide that produce around 95 percent of the world’s supply of flat glass. While each plant is different from the other, their production processes can be divided into six steps.

Batch mixing
The raw materials (silica sand, calcium, oxide, soda and magnesium) are properly weighed and mixed and then introduced into a furnace where they are melted at 1500° C. The use of ?cullet? reduces the consumption of natural gas while melt colorants are added to produce tinting and solar-radiation absorption properties. The melting process is crucial to glass quality.

Float bath
The molten glass then flows from the glass furnace into a bath of molten tin in a continuous ribbon. The glass, which is highly viscous, and the tin, which is very fluid, do not mix and the contact surface between these two materials is perfectly flat.

Coating
In this process, metal oxides are directly applied to the glass, while the glass is still hot, in the annealing lehr.

Annealing
When it leaves the bath of molten tin the glass has cooled down sufficiently to pass to an annealing chamber called a lehr. Here it is cooled at controlled temperatures, until it is essentially at room temperature.

Inspection
Final inspection ensures the high quality of glass.
After this the glass is ready to be cut and shipped.
A float plant which operates non-stop for about 15 years makes around 6000 kilometers of glass annually, in thicknesses between 0.4mm to 25mm and in widths up to 3 meters. A float line can be nearly half a kilometer long.