Repairing Plaster Walls With Joint Compound

Drill a series of holes to each side of the crack in the plaster, using a drill with a masonry bit. Drill into the wall, stopping when the bit hits the wood lath underneath. This prepares the plaster for the application of an adhesive that will reset the bond between the plaster and the lath underneath. Vacuum out the holes you've drilled to remove any loose debris.

Spray a small quantity of plaster adhesive conditioner into each of the holes. Wipe away any excess on the wall with a damp rag. Insert the tip of the caulking gun with the tube of adhesive inserted and pump a small quantity of adhesive into each hole. Wipe away any excess with a damp rag.

Screw a plastic ring with a drywall screw into the crack every 3 to 4 inches. Tighten until the plaster snugs up against the lath and pushes a small quantity of adhesive out of the adjoining holes. This clamps the plaster to the lath until the adhesive dries. Remove the clamps when the adhesive is dry, according to the directions on the adhesive.

Scrape off any high points on the plaster with a 6-inch putty knife. Apply a coat of joint compound with a putty knife and spread it over the holes and cracks. Let the joint compound dry overnight.

Sand the wall with sandpaper and a sanding block until it's smooth. Paint the wall to finish the job.