The Effect Of Small Additions Of Sodium Sulphate On The Refining Of Glass

The effect of varying the time of melting of a soda-lime-silica glass between 3-4 hours and of the addition of sodium sulphate up to 20 parts per thousand of sand, has been investigated at a temperature of 1420 deg C with a controlled melting atmosphere. The results show that additions of 7-20 parts sodium sulphate per thousand sand markedly improve the refining of the melt but lower sulphate levels may have a detrimental effect.