Fine-grained ingredients, closely controlled for quality, are mixed to make batch, which flows as a blanket on to molten glass at 1,500 oC in the melter.
Float makes glass of near optical quality. Several processes – melting, refining, homogenising – take place simultaneously in the 2,000 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 1,100oC, 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.