The Behaviour of Glasses under Treatment by the Blow-Lamp Flame
JSGT 1936 V20 T152-T169
The defects in glasses due to treatment by the blow-lamp flame are discussed. The chief troubles originate in the more readily volatile components of the glass. Blackening and clouding are due to arsenic, antimony, lead, and manganese; halo formation and roughening in all probability to the alkalis. The foam formations occurring with the high softening boric acid glasses are caused by marked boric acid evaporation. The appearance of hydrogen or oxygen bubbles in electric lamp glasses as well as the very violent foaming of the high softening-point glasses of the SiO2–Al2O3–CaO–BaO system have not as yet been fully explained.
M. Thomas
