DIY Drywall Finishing for Inside Corners

Cut strips of paper drywall tape for each inside corner to be finished. Cut the tape just a little longer than the required length. Fold each piece of tape at the center crease and set aside. Fill a mud pan with ready–mixed joint compound and apply a thick coat to each side of the inside drywall corner.

Start at one end of the wall and place the folded paper tape into the mud with the crease in the corner. 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.

Use a 6 inch joint knife to skim one surface at a time. Hold the joint knife at about a 30° angle and skim the mud from between the tape and drywall. Start a foot or so out and skim back toward the beginning to avoid lifting the end of the tape. Then skim the rest of the tape in the opposite direction.

Keep the knife pressed hard against the wall as you skim. Be careful not to tear the tape with repeated strokes. If this happens pull the tape out straight and skim it out again. Skim the same stretch of tape a few times if necessary to remove all the excess mud from between the tape and drywall. Return the excess mud to the pan frequently to avoid buildup. Before moving on be sure the tape is tight and smooth against the drywall.

Skim the other side of the corner in the same way working on a few feet of tape at a time. Continue with this process to finish the remaining seams. If the tape bunches up or tears, straighten the ruffles and smooth it out with the a little compound and the knife. Allow the mud to dry for a couple of hours. During this time return the unused joint compound to the bucket and cover it to keep it from drying out.

When the corner has dried for a couple of hours, apply a second thick coat of mud to each surface. Work on a 5 or 6 foot section at a time. Skim the excess mud from the corner using the same technique used with 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 joint knife will ruffle the point where the two planes meet, this will be corrected in the next step. Let the mud dry for a couple of hours or more.

Apply another coat over the joint if necessary to finish and completely cover the tape. Let the final coat of mud dry thoroughly before moving on.

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. Allow the joint compound to dry for 6 to 12 hours. Lightly sand the dry mud with 120 grit medium sandpaper to smooth the surface and feather the edges into the surrounding wall. Brush any dust from the walls 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.