Drywall compound must be applied in several thin coats because thick applications tend to shrink and crack. Also, thin coats can be feathered or tapered very gradually so that they’re invisible (or nearly so) after the drywall surface is painted. Before applying the second coat, remove any lumps, high spots, or ridges of hardened compound left from the first coat. This can be done with a drywall knife or a pole sander. Be careful not to oversand, or you could damage the paper face of the drywall.
Apply topping compound over the dimples around the fasteners, just as you did with the first coat. Be even more careful as you level the compound, and use a 10-in. or 12-in. knife. Along seams, apply topping compound with a 5-in. knife, then use a 12-in. knife to remove the excess (see the top photo on p. 229). Again, take your time. The second coat should conceal the tape. Using a wider knife, feather the mud away from the center of the joints to make them harder to detect. This is especially important
at butt joints. It takes some practice to get this coat right. Go over the joints more than once, if necessary, pulling the knife with a steady, even pressure to leave a smooth surface.
The same can be done along inside corners, using a 5-in. knife to mud and smooth one side of the corner at a time. This takes some skill, because it’s difficult to keep the knife from marking the finished side as you mud the opposite side. For this reason, some tapers like to use a different procedure. They apply mud on one edge at a time, smooth it, and then let it dry. Once one side of the corner is dry, they return and do the other side.
Before applying the third coat of compound, lightly sand the second coat. Hit the corners, dimples, and seams with a 120-grit screen on a sanding pole to remove any bumps, trowel marks, or ridges. The third coat should be little more than a light application of topping compound to hide any imperfections and feather the seams a bit wider. To make the topping compound easier to manipulate, thin it with a little water.
The drywall in many houses, especially in the West and Southwest, is textured by using air to blow on a solution of drywall mud. [Photo by Don Charles Blom]
