How to Sand Drywall and Drywall Mud Successfully

Wait for your drywall mud to completely dry because sanding wet mud can result in gouging and ruining the mudding job, forcing you to start over. How long does drywall mud take to dry? Expect to wait 24 hours to allow everything to dry properly.

One clarification: When people talk about sanding drywall, they’re talking about sanding the drywall mud, not the paper covering on the sheet of drywall itself. By sanding, you remove slightly uneven spots and bumps in the mud, creating a flat wall that’s ready for paint. With proper sanding, you can achieve a level 4 drywall finish.

Drywall dust is infamous for getting everywhere in your home and is very time-consuming to clean. Secure plastic sheeting over all entrances to the room with painter’s tape and close all vents to limit dust moving through the air into other parts of your home.

Lay a drop cloth or plastic sheeting on the floor to protect it and reduce cleanup time. Cover your furniture with plastic sheeting, too.

Always wear protective clothing, including safety goggles, work gloves, and a sanding respirator, when sanding. Sanding drywall puts silica dust into the air, which can cause lung irritation and shortness of breath (or worse with prolonged exposure). Wearing a sanding mask is absolutely critical.

With a drywall sponge, wet sand your drywall to smooth out ridges and gouges. Soak your drywall sponge in water and wring out the excess. Gently rub the sponge in a circular motion on the drywall mud until you have a relatively flat surface, including the edges. If the sponge dries out, rewet it and squeeze out the excess water.

Let everything dry to see what imperfections remain. Repeat the wet sanding process if necessary, or move on to dry sanding.

Wet sanding significantly reduces the dust in the air, and a sponge is the best tool to use in corners because sandpaper can cause gouges. 

Place your sandpaper on a pole sander for high spots and on a sanding block for middle and low parts of the wall. Use 120-grit sandpaper when the mud is roughest (for instance, if you skipped the wet sanding step). Then, switch to 150-grit sandpaper for smoothing moderate roughness. Use 220-grit sandpaper for fine sanding and final touches. 

Here are some tips for sanding drywall:

• Apply light pressure and work in a push-pull motion in an overlapping pattern with even pressure. 

• Feather the edges to create smooth seams and a polished finish. 

• Use a very light touch across screw holes and seam tape. 

• Use fine-grit sandpaper to flatten areas with too much mud or where the mud has gouges. 

• Use a sandpaper block when finishing areas around electrical outlets and switch plates.

Vacuum the walls from the ceiling to the floor with a shop vac to remove drywall dust. Carefully remove the drop cloths and plastic sheeting. Vacuum the floors until the room is dust-free. Gently wipe down the walls with a slightly damp cloth to remove lingering dust. Once your walls are completely dry, they’re ready for priming and painting.