Evolution Of The Compositions Of Commercial Glasses 1830-1990. Part 1: Flat Glass

More than 500 analyses of flat glasses made since 1830 in 17 countries have been analysed statistically. They include samples made by all the commonly used processes. The purpose of the analysis was to investigate differences related to type of process, region of manufacture, and the passage of time. Changes in the use of the various important constitutents are demonstrated and commented on. In the early years of the 20th century, only sulphate was used as refining agent and high SO3 contents were found until 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.