Mix at slow speed until water is blended and compound is smooth. If there's no water, the compound is ready to use. • Look for any screwheads poking above the drywall surface and drive them until slightly recessed. • Tear away any loose or torn paper from drywall (especially at corners and cut edges) to prevent bits from ending up in the compound. Note that some drywall installers find it easier to let the joint compound dry overnight at this stage, before applying the second coat with the 8-in. knife. After the butt joints are taped smooth ...

Maybe the drywall installers did a poor job hanging the drywall or finishing it. The builders may not have taken care while framing the wall. The result: walls that aren’t flat and even. Whether seams show, the wall appears to bow and dip, or the drywall has suffered a ding or two over the years, you can smooth it out with a skim coat.