Open-coat abrasives have grain covering roughly 50–70% of the surface, leaving gaps that resist clogging when sanding soft or resinous materials like wood or paint. Closed-coat products have full grain coverage for faster cutting on harder surfaces. Both fall under 66322, but buyers should specify coating density in purchase orders to ensure the correct product is shipped and inspected.

Certain coated abrasive products sourced from specific countries have been subject to antidumping or countervailing duty investigations historically. Importers should check the US International Trade Commission and Commerce Department databases for active orders covering paper-backed abrasives before finalizing supplier contracts, as duty liability can significantly affect landed cost.