How to Sand Drywall Corners
- 1). Spread the first coat of joint compound over both sides of the corner, meeting at the middle. Make the compound about 1/8-inch thick (just enough to cover the tape or cornerbead that was used to form the corner), and have it extend about 3 inches out from the corner on both sides. Get the line of the corner as straight as you can. Let it dry for four to six hours.
- 2). Run a drywall sander along the length of the corner, with the pad of the sander positioned so that it completely covers the width of the compound area on each side. Sand back and forth with moderate speed and pressure in roughly 1-foot-long strokes, getting the compound smooth and flat. Make sure to "feather'' it at the outer edges, so it gradually gives way to the surrounding drywall.
- 3). Apply a second layer of joint compound in the same way as the first, but make the seams a little wider on each side of the corner, about 4 inches instead of 3 inches. Let it dry.
- 4). Re-sand the second layer in the same way as the first, with roughly 1-foot strokes, feathering it along the edges.
- 5). Apply a third coat of compound, making it about 5 inches wide on either side of the corner. Make it thinner than the previous coats, so it's just a "skim'' coat. Let it dry.
- 6). Sand the final coat very lightly, just enough to smooth it out. Make sure the corner is nice and straight.
