3M SCOTCH BLUE MASKING TAPE Our most popular tape! Conforms well to curves. Excellent in topside painting, varnishing and caulking applications. 3 M Scotch Blue Long-Mask masking tape uses a synthetic adhesive system providing ultraviolet stability and adhesive transfer resistance for up to seven days after application. Controlled crepe paper backing makes this tape smoothly conform to curves in various paint and varnish masking applications. Excellent in topside painting, varnishing and caulking applications. Sold by the roll.