3M dry guide coat is used to identify surface imperfections such as pinholes in body filler and deep scratches in primer. Unlike liquid and aerosol guide coats, dry guide coat requires no masking before use and there is no dry time after application. The dry formula contains no intentionally added solvents and doesn't clog sandpaper while delivering easier cleanup. 3M dry guide coat is used in the dry primer sanding process to identify surface imperfections such as pinholes and deep scratches in primer. When sanding polyester filler, it ensures the filler is flat with no ripples and that the body styling lines and contours are straight and correct. It also ensures the total primed area is sanded prior to top coating. Using this product prior to priming and sanding will save you rework later when surface imperfections would otherwise appear. You get superior visualization so you can correct problems early before they become bigger problems later. Once blemishes become evident after priming or painting, you have a choice to compromise the quality of the job or do costly rework. 3M dry guide coat saves you from that tough decision. This dry guide coat is a carbon black powder that can be used on automotive and marine fillers, primers, paints and gelcoats. It may be used for either wet or dry sanding. The powder contains no intentionally added solvents that can cause painting problems.