Granted Patent
Utility
US 4,886,539 · App. 07/331,780
Method of vacuum refining of glassy materials with selenium foaming agent
Inventors:
Richard L. Gerutti, David R. Haskins, Robert B. Heithoff, Ronald L. Schwenninger, Wright M. Welton
Patented Case
View Patent ↗
Granted: Dec 12, 1989
Filed: Apr 3, 1989
Inventors
Richard L. Gerutti
David R. Haskins
Robert B. Heithoff
Ronald L. Schwenninger
Wright M. Welton
Assignee (at issue)
PPG Industries, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.