The Softening of Glasses at High Temperatures

JSGT_1937_V21_T113_T122

A method is described by which the behaviour of a glass at high temperatures associated with softening and devitrification may be rapidly determined. Variations in the dimensions of the test-pieces are due to the combined effects of the properties, viscosity and surface tension, and the behaviour of glasses of different types depends on these properties. The lower temperature limit of devitrification may be reduced slightly on prolonged heating, but the upper temperature limit is almost unaffected by such treatment.

I. Sawai & I. Kubo