Melting
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.

Batch mixing and refining
Fine-grained ingredients, closely controlled for quality, are mixed to make batch, which flows as a blanket on to molten glass at 1,500°C in the furnace. Float today makes glass of near optical quality. Several processes - melting, refining, homogenizing - take place simultaneously in the tonnes of molten glass in the furnace. They occur in separate zones in a complex glass flow driven by high temperatures. It adds up to a continuous melting process, lasting as long as 50 hours, that delivers glass at 1,100°C, free from inclusions and bubbles, smoothly and continuously to the float bath. The melting process is key to glass quality; and compositions can be modified to change the properties of the finished product.