A Suggested Procedure for the Examination after Failure of Glass-Melting Pots

JSGT 1943 V27 T053-T059

This account of the examination after failure of open pots made of a sillimanite-ball clay mixture is given to encourage the wider adoption of photographic and petrological methods in the examination and recording of the performance and failure of glass-melting pots. It is illustrated by reference to studies of the performance of pots employed in the founding of a hard borosilicate glass at a temperature of 1470–1480°. Long pot life is not expected when melting this type of glass, but failure seemed to be due in the cases examined to shot-holing of the pot wall, pointing to local inhomogeneity, possibly due to large iron spots, or to inadequate pugging and mixing, or to slight differences in texture. A feature of the defective parts was the pronounced mullite development, and appeared due to the effect of B₂O₃ vapour on alumina-silica refractories; for it was noted also on gathering hoods at 1350° and on the crown of an electric furnace melting a very high B₂O₃ content glass at 1250°.

Eric Preston