Granted Patent
Utility
US 4,713,294 · App. 06/866,438
Foundry shell core and mold composition
Inventors:
David R. Armbruster, Calvin K. Johnson
Patented Case
View Patent ↗
Granted: Dec 15, 1987
Filed: May 23, 1986
Inventors
David R. Armbruster
Calvin K. Johnson
Assignee (at issue)
Acme Resin Corp.
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.