Granted Patent
Utility
US 5,393,794 · App. 08/049,569
Insulation material and method using fly ash
Inventor:
Henry Sperber
Patented Case
View Patent ↗
Granted: Feb 28, 1995
Filed: Apr 19, 1993
Inventor
Henry Sperber
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.