DIY Drywall Finishing Inside Corners
Also see:This page contains taping and finishing instructions for inside drywall corners. Go to Installing Drywall Corner Bead and Finishing Drywall Seams for help with those projects and see drywall finishing materials and techniques for more about drywall finishing.
Fold Paper Drywall Tape
Finish inside drywall corners using paper drywall tape, not fiberglass mesh. Cut the tape, squarely, a little longer than the corner to be finished and fold it along the center crease.
Use Ready–Mixed Joint Compound
Use ready–mixed joint compound or mud for this job, setting–type joint compound will harden too quickly, causing problems. See Drywall Finishing Tools and Materials for more information about drywall finishing tools, tapes and joint compounds.
Apply Mud to the Corner
Use a joint knife and mud pan to apply a thick coat of joint compound to both walls, along the whole length of the corner.
Set the Tape
Start at one end of the corner and place the folded paper tape into the mud. Open the tape and gently press it down so it makes contact with both surfaces. At the end of the corner cut the excess tape to the proper length.
Skim the Mud
Use a small joint knife to skim one wall at a time. Hold the joint knife at about 30° and skim along the tape to press it down and remove the excess mud. Scrape the knife blade on the mud pan frequently to keep it clean.
Skim Again
To insure the tape won't come loose over time, go over it again, pressing harder with the blade, to squeeze all the excess mud from between the tape and drywall. If there is too much mud under the tape it can cause it to pop free with normal expansion and contraction in the wall.
Be careful not to tear the tape with repeated strokes. If the tape bunches up or tears, straighten it out and smooth it again with the knife and a little joint compound if necessary. Before moving on, be sure the tape is tight and smooth against the drywall.
Apply a Second Coat
Allow the mud to dry completely and apply a second, thick coat to both walls.
Skim the Second Coat
Skim the excess mud from the corner using the same technique as the first coat. Don't be concerned that the mud doesn't come together at the corner in a perfectly smooth finish. The edge of the knife blade will ruffle the point where the two planes meet, this will be corrected in the next step.
Finish Coat
Let the mud dry for a couple of hours or more and apply another coat of mud if necessary to completely cover the tape. Skim along the edges of the mud to avoid a buildup that will require a lot of sanding later. Let the final coat of mud dry thoroughly before moving on.
Finish the Corner Crease
Remove any particles of dry mud from the corner using sandpaper or a putty knife. Add a small amount of mud to the pan. Use your index finger to spread wet mud along the corner to fill and smooth out the crease.
When the mud is dry lightly sand with 120 grit medium sandpaper to smooth the surface and feather the edges into the surrounding wall. Wipe the dust from the walls with a damp cloth before priming and painting. Use one coat of drywall primer if you are using flat latex finish paint. If you are using semi-gloss or other shiny paint, prime with 2 coats of latex primer.
