To repair a plaster wall, protect walls and floors near the repair area with plastic drop cloths. Using the painter’s tape, hold the drop cloths in place. With a masonry drill bit, bore holes through the plaster, but not through the wooden lath.
Evenly space the holes about 3 inches apart around the damaged area. Clean any debris from the holes using a wet cloth. Spray liquid conditioner into all of the holes, and use a sponge to remove any excess conditioner that runs down the wall. Pare the adhesive tube’s nozzles using a utility knife. After trimming, dispense the adhesive into each hole, and immediately, use a drill to screw a plaster ring into as many holes as possible to pull the plaster tight against the lath.
Give the adhesive time to dry, and then withdraw all the screw and plastic rings using the drill. Use a 6-inch putty knife to remove any high points of the adhesive. Smear a thin coat of joint compound to the wall with the putty knife. Allow the mixture to dry, preferably overnight. Using a 120-grit sand paper, sand the surface with little force. After sanding, apply a second thinner compound coat. Finally, prime and paint the wall.