The Routine Control by Density and Thermal Expansion Measurements of Glasses during Manufacture.

JSGT 1949 V33 T188-T198

In the case of glasses where a specification demands a close tolerance for thermal expansion coefficient, it is essential to ascertain this characteristic quickly. A survey of many determinations of density and thermal expansion coefficient indicates that when the glass composition fluctuations are within reasonable limits a parallelism exists between density and thermal expansion coefficient values. Thus, density determinations, on account of the ease with which they can be carried out, can be employed for primary control, and the thermal expansion measurements desirable for purposes of confirmation can be made at less frequent intervals. Types of apparatus used are described, together with the glass-sampling and annealing techniques employed.

P. Staton & P. Maycock