Granted Patent
Utility
US 5,891,236 · App. 08/844,976
Process for improving the color and brightness of discolored goethite-containing materials
Inventors:
Jessica E. Kogel, Randy K. Hall
Patented Case
View Patent ↗
Granted: Apr 6, 1999
Filed: Apr 23, 1997
Inventors
Jessica E. Kogel
Randy K. Hall
Assignee (at issue)
Thiele Kaolin 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.