Evolution of the compositions of commercial glasses 1830 to 1990. Part I. Flat glass

Abstract

More than 500 analyses of flat glasses made sinee 1830 in seventeen eountries have been analysed statistieally. They inelude samples made by all the eommonly used proeesses. The purpose of the analysis was to investigate differenees related to type of process, region of manufacture, and the passage of time. Changes in the use of the various important constituents are demonstrated and commented on. In the early years of the twentieth Century only sulphate was used as refining agent and high SO3 contents were found until around 1960. Other constituents, such as BaO and B2O3, were tried but did not gain acceptance. As time went by variations within any company decreased and compositions of all flat glasses converged. Differences in flat glass compositions produced by different processes were rather random as were differences between various countries.