US2322156A US424998A US42499841A US2322156A US 2322156 A US2322156 A US 2322156A US 424998 A US424998 A US 424998A US 42499841 A US42499841 A US 42499841A US 2322156 A US2322156 A US 2322156A Authority US United States Prior art keywords adhesive filler coat abrasive fillers Prior art date 30 Legal status The legal status is an assumption and is not a legal …