Ppg Industries, Inc.

Wright M Welton

Ronald L Schwenninger

Larry J Shelestak

Robert B Heithoff

Joseph M Matesa

David R Haskins

Boyd S Dawson

Richard L Gerutti

In a method of vacuum refining molten glass or the like, selenium is provided in the molten glass to serve as a foaming agent, which yields improved refining. Alternatively, colored glass compositions that include selenium as a colorant are refined at higher than normal pressures to retain selenium in the glass without sacrificing refining performance.

Method of vacuum refining of glassy materials with selenium foaming agent

In a process for refining molten glass or the like by vacuum, the collapse of foam is accelerated by contacting the foam with foam breaking substances. The foam breaking substances include water, alkali metal compounds such as sodium hydroxide or sodium carbonate, and solutions of such compounds.

Foam control method for vacuum refining of glassy materials

Foaming of molten glass or the like as it enters a vacuum refining vessel is enhanced by altering the incoming stream so as to increase its surface area and/or retarding the passage of the stream through the vacuum headspace so as to increase its exposure to the vacuum.

Vacuum refining of glass or the like with enhanced foaming

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Oldtown, MD, United States of America

Wright M Welton