How to Sand Damaged Plaster Walls

Chip away any loose or flaking plaster using a putty knife. Sanding parts of the plaster that are not stable is simply a waste of time, because they will eventually fall off. Push the putty knife under the edge of the remaining plaster around any holes, and knock away any part of the wall that isn't structurally sound.

Fill in any gaps, holes or cracks in the walls with fresh plaster if you are completely repairing the wall before sanding it. If you are simply sanding the wall down in preparation to paint it or in an effort to improve its appearance without getting into the work of fresh plaster, skip this step.

Sand the plaster with a coarse grit sandpaper first to scrape away any large defects. Starting with 80-grit sandpaper is usually sufficient for plaster.

Continue to sand the surface of the plaster with increasingly fine grits of sandpaper until you have reached your desired level of smoothness on the wall.

Apply primer and finish paint on the wall to protect and stabilize the primer and to make the wall look better.