As basic and seemingly non-technical as it may seem, to sand drywall and prepare it for painting is one of the more important keys to the quality painting of a home's interior. It can also be one of the most unpleasant, and thankless, jobs in home construction and remodeling.
It's a job that is typically low paying and high risk, because of the dust that pervades everything thing around it. But if you are remodeling your own home, and if you are planning to do all the drywall and painting work, you will need to deal with the challenge of drywall sanding. Here are a few tips you'll find useful.
Seal your home off to protect it from drywall sanding dust. This dust is pervasive and so fine it sometimes seems impossible to clean up and remove. Keep interior doors to your home closed to keep this dust out of it. In the rooms where you plan to sand your drywall, open windows to the outdoors and remove window screens that can become clogged with this dust. Seal HVAC ducts with masking tape. Remove from the room anything you don't want to be covered or penetrated by dust. Most importantly, wear a respirator and goggles. Breathing this dust can be deadly.
Your drywall may seem to be ready to sand, but what you may not see are the hollows, dents, scratches, and pinholes that may not be readily visible and that can fill up with sanding dust as you sand. These voids and hollows are more easily found by your feeling them, than by your seeing them.
You have a better chance of seeing them if you use a lamp or work light. Turn the light on and hold it close to the wall, so it creates shadows where there are ridges and voids in your drywall seam surfaces. To feel those voids you don't see, run your fingertips along the taped seams. You'll feel the voids. Use your drywall knife to fill them with mud. Then give the new compound you've applied time to dry.
Sand the Seams
Begin by sanding, with coarse sandpaper that will more quickly sand down ridges and other high places made by the compound application. Use a hand sander for surfaces you can reach. Use a pole sander for ceiling surfaces. To do the finish sanding, use a finer (150 grit) sandpaper. To sand more efficiently, use pushing and pulling motions of your sander. Avoid putting too much pressure on seam paper. This can scuff paper edges, requiring you to reapply compound,
Sanding the Corners and Fittings
Techniques for sanding straight drywall seams will not work well for sanding inside corners and edges around outlets, HVAC ducts, etc. Use only a hand sander in these areas. Avoid using power sanders in these spots because of the scratches and dents they can make by striking wood and metal surfaces near sanding areas. Damp sanding sponges also work well for smoothing these hard-to-sand areas.