Granted Patent
Utility
US 4,376,673 · App. 06/235,809
Method for etching dental porcelain
Inventor:
Peter P. L. Cheung
Patented Case
View Patent ↗
Granted: Mar 15, 1983
Filed: Feb 19, 1981
Inventor
Peter P. L. Cheung
Assignee (at issue)
Pennwalt Corporation
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.