The most important raw material for the production of float glass is quartz sand, a material that is abundant in nature and will be available in sufficient quantities for future generations. Soda, dolomite (lime) and other raw materials are needed in small quantities. To improve the melting process, approx. 20 % clean glass shards are added to the mixture. These raw materials enter the melting furnace as a mixture and are melted there at a temperature of approx. 1550 °C. The liquid glass is added to the float bath of liquid tin. On the molten tin the glass mass "floats" in the form of an endless band. Due to the surface tension of the glass and the flat surface of the tin bath, a plane-parallel, distortion-free glass ribbon of high optical quality is formed. In the cooling tunnel and in the subsequent open roller conveyor, the glass strip is continuously cooled from 600 to 60 °C, checked for defects by laser and then cut to glass sheets of 6000 x 3210 mm.