Granted Patent
Utility
US 4,802,321 · App. 07/196,180
Sag resistant ceiling panel
Inventor:
Robert J. Menchetti
Patented Case
View Patent ↗
Granted: Feb 7, 1989
Filed: May 18, 1988
Inventor
Robert J. Menchetti
Assignee (at issue)
National Gypsum Company
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.