Granted Patent
Utility
US 4,248,220 · App. 06/074,210
Disposable dust respirator
Inventor:
Willard C. White
Patented Case
View Patent ↗
Granted: Feb 3, 1981
Filed: Sep 10, 1979
Inventor
Willard C. White
Assignee (at issue)
American Cyanamid 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.