Granted Patent
Utility
US 4,256,497 · App. 06/119,938
Lead-free glaze for alumina bodies
Inventor:
Randy O. Knapp
Patented Case
View Patent ↗
Granted: Mar 17, 1981
Filed: Feb 8, 1980
Inventor
Randy O. Knapp
Assignee (at issue)
Champion Spark Plug 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.