Sir Alastair Pilkington's innovation in the 1950s, the float glass process, now dominates global flat glass production, accounting for 90% of it. This process involves pouring molten glass onto one end of a molten tin bath. The glass floats, levels itself, and solidifies as it travels over the tin, producing smooth surfaces on both sides. After leaving the tin bath, the glass is annealed in a lehr, resulting in a product with almost perfectly parallel surfaces.

A small portion of the tin merges with the glass on the contact side, which is subsequently easier to convert into a mirror. This feature has largely replaced older plate glass methods. The tin-impacted side is also notably softer and more prone to scratches. Float glass is available in standard thicknesses from 2 mm up to 22 mm.

The thickness control of the glass, as it floats in a controlled nitrogen/hydrogen atmosphere, relies on surface tension, which naturally limits the spread to about 6 mm. To produce thinner glass, the float is stretched while cooling, and for thicker glass, the spread is constrained.