Degassing behavior of optical glasses

Abstract

The suitability of high-vacuum extraction for judging the "fining condition" and the "fining behavior" of selected optical glasses as well as for tracing the fining process in glass melting tanks is being demonstrated. Degassing of optical glasses examined occurs in three steps, with oxygen representing the main share of extractable gases. The specific parameters for the characterization of the instantaneous quality of the glass melt in a glass melting tank are the differences of mean bubble size in samples taken from different locations and of "physically" as well as "chemically" dissolved oxygen. The fining mechanism of a soda—lime—silica and of a lead—silica glass are discussed.