How to Use a Drywall Knife

Place a small dab of joint compound on the flat portion of a 3- or 4-inch drywall knife near the edge. Hold the tool with the joint compound against the drywall, and slide the knife along the surface. The joint compound should fill the nail holes in the drywall.

Allow the drywall compound to dry overnight and sand smooth.

Apply a second layer of joint compound with a 6-inch drywall knife, following the same procedures. Use a wider drywall knife to apply each subsequent coat of joint compound. This spreads the joint compound over a larger area, creating a smoother transition between the compound and the drywall.

Apply a thin coat of joint compound over the seam between two sheets of drywall, using a 3- to 4-inch drywall knife. Press the joint tape into the compound by running the edge of the drywall knife blade along the joint. Allow the material to dry overnight before sanding the rough edges down.

Place another layer of joint compound on the seams with a 6-inch drywall knife. Allow this coat to dry overnight before sanding smooth.

Use a corner drywall knife to apply joint compound on inside or outside corners. This drywall knife has a blade shaped into a right angle. Apply the joint compound on the inside of the blade for work on outside corners, and along the outside of the angle for applications in inside corners.