3M Pro grade block sanding sponges are made to sand flat, contour or irregular surfaces. The professional grade foam is comfortable to grip and maintains its shape through a variety of sanding jobs. Sanding is an integral step in preparing a surface to receive a coating. For the best sanding results, sand with the grain of the surface and work through a sequence of grits, from coarse to very fine, skipping no more than one grit between each sanding step.