Use sanding sponge for bare surface sanding to remove flaws or blemishes before applying initial coating. Best used on paint, wood, metal and drywall. Unique sponge channels dust away from the sanding surface. Use the pattern side for detail sanding and superior conformability. Use regular side for flat sanding. Lasts 5X Longer than 3M conventional sanding sheets. Made of premium aluminum oxide mineral. Clog resistant for longer sponge life. Washable and reusable. Use wet or dry. For best results, sand with grain of surface and work through sequence of grits, from coarse to very fine, skipping no more than 1 grit between each sanding step.