How to Repair Plaster Sprayed Ceilings

Cut around the entire crack with a utility knife. Cut deeply enough to remove all of the plaster approximately ½-inch from each long edge of the crack so that the ceiling substrate is exposed. Vacuum thoroughly over the crack with the upholstery brush attachment of a heavy-duty vacuum cleaner and then wipe the crack inside and out with a damp sponge.

Mix together the setting joint compound and the amount of water required for your particular product. Find this information on the package; it may vary by brand. Stir the compound well with a mixing paddle until the consistency is similar to spreadable margarine.

Scoop up some of the prepared joint compound on a 6-inch joint compound knife. Spread it from the center of the crack toward one long edge, pushing the compound against the side of the crack to create a seal. Repeat this process for the opposite side, spreading the compound from the center of the crack toward the other long edge.

Hold the joint compound knife so that the tip is angled 45-degrees and drag it over the surface of the repair to remove any excess compound. Wait five to six hours for this layer to dry. When you see the compound shrinking away from the edges, it is time to apply a second layer.

Mix and apply a second layer of joint compound just as you did the first. Let the layer dry, then apply a third and final layer. Wait 24 hours.

Sand the surface of the completed repair using a manual sanding block loaded with 150-grit sandpaper. Sand evenly over the compound until the surface is smooth with the rest of the ceiling and the repair is nearly indistinguishable from the surrounding ceiling. Wipe the area with a rag to remove sanding dust and debris.