The main constituent of flat glass is SiO₂ (silica sand). This has a high melting temperature in the region of 1700°C and its state at this temperature is like syrup on a very cold day.

The basic building block of silica has a tetrahedral pyramid shape with silicon at its centre linked symmetrically to four oxygen atoms at its corners: it has the chemical formula SiO₄ and is negatively charged.

On cooling molten silica quickly, a random organised network of these tetrahedra are formed, linked at their corners, to give an amorphous material known as vitreous silica.

Other raw materials include soda ash, dolomite, limestone, saltcake, and broken glass (cullet). We melt this mix at white heat to a highly viscous consistency.

This is the mix and process for many types of mass-produced glass; except that float demands highly exacting standards of quality, care and control beyond those of other everyday uses of glass.