Granted Patent
Utility
US 4,806,509 · App. 07/129,213
Aluminum resistant refractory composition
Inventor:
Andrew Porterfield
Patented Case
View Patent ↗
Granted: Feb 21, 1989
Filed: Dec 7, 1987
Inventor
Andrew Porterfield
Assignee (at issue)
VFR, 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.