Evolution Of The Compositions Of Commercial Glasses 1830-1990. Part Iii. Pressed Glass

This paper considers the evolution of glasses used for pressed wares in the way already used for flat and container glass. Around 160 samples of common pressed soda-lime-silica glass used for utilitarian and technical purposes are considered. The composition of pressed glass is related to flint container glass, it differs mainly in higher alkali content, low iron content and, from time-to-time, in additions of K2O and BaO. Development of the compositions of flat, container, and pressed glasses is then compared and notable features such as the introductions of magnesia and alumina discussed, as is the use of high-alumina low-alkali container glasses. How future constraints may affect further developments are also considered.