The production of float glass begins by melting glass in a furnace at a high temperature. The molten mass is poured into a billet that has liquid tin at the bottom. This process is known as the Pilkington process.
In the furnace chamber, the glass floats on the surface of the tin, taking its shape. The glass is then slowly cooled in a setting, a leer, to release the internal stress. This cooling process, known as annealing, is critical to the success of the final product. It is important to note that the top surface of the glass, called the air or cut surface, is fire polished, while the underside, which is in contact with the tin, remains unpolished. After annealing, the glass emerges as a continuous ribbon that is automatically cut to the required dimensions and packaged for transport.