Plaster board is one of the most common type of walls. Cracks in plaster board, which is a gypsum plaster center bonded to layers of fiberboard, can be repaired with a special drywall repair tape and plaster. Cracks can be caused by shifting and settling of a building, or by the holes made to hang pictures or fixtures. The process of patching a crack in plaster board actually first makes the crack deeper and wider, which looks distressing, but results in a more satisfactory repair.
Score and define the plaster board crack with a screwdriver or other sharp edge. A can opener works well. Clean dust and debris from area around the plaster board crack.
Cover the plaster board crack with self-adhesive fiber mesh.
Mix all-purpose drywall compound with water, following the manufacturer's instructions.
Apply the drywall compound to the plaster board crack, over the drywall mesh, with a drywall knife. Several coats may be required; the level of the repair should be flush with the wall surface.
Sand the repaired plaster board crack with fine sandpaper. Prime and paint to match.