Some features of the melting of borosilicate glasses in continuous furnaces

The quality of G40-1 glass obtained in continuous gas furnaces was studied. The solubility of the gases in the G40-1 glass was determined for acceptable articles obtained in the two furnaces. The effect of repeat heating of the G40-1 glass in the forming zone was studied to find reasons for the formation of seeds and bubbles. It was shown that they form when scale from hot angle-bar supporting the plate-blocks of the crown fell into the glass of the working end of the furnace if the lining of the curtain wall has not been adequately sealed. When borosilicate glass with a large concentration of the boron oxide phase was melted in continuous furnaces it was not permissible to have a positive pressure of the gas medium in the sub-crown space.