3M Wetordry allows you to sand between coats of varnish and paint or other finishes. Can be used with water to reduce clogging and extend abrasive life. Ideal for sanding metal for repainting or prior to primer coat.3M General Purpose Sanding Pads are designed for sanding surfaces such as wood, paint, metal, plastic and drywall. Extremely flexible pads best used for sanding contoured surfaces and hard to reach places. Pads can also be used for sanding flat surfaces. Resists clogging and can be used for wet or dry sanding.