Granted Patent
Utility
US 4,306,980 · App. 06/099,711
Invert emulsion well-servicing fluids
Inventors:
Israel M. Brandt, Forest A. Scearce
Patented Case
View Patent ↗
Granted: Dec 22, 1981
Filed: Dec 3, 1979
Inventors
Israel M. Brandt
Forest A. Scearce
Assignee (at issue)
NL Industries, Inc.
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.