It just takes a little spackling compound to repair fine cracks, nail holes, and gouges in plaster.
You will need:
* Spackling compound
* A lever-type can opener
* A sanding block
* A putty knife
Use the point of the can opener to widen the crack to 1/8 inch, as shown at bottom left. Blow out the plaster dust. Fill the crack with spackling compound, using a putty knife or your finger, as shown. Let the spackling compound dry and then sand it with fine-grade sandpaper wrapped around a sanding block. Prime the patch with sealer and then finish to match the wall.
Larger cracks can be fixed in a similar way. Widen the crack with the can opener and dampen the edges of the crack with a sponge. Fill the crack half full with patching plaster. When it has dried a little, score the plaster with a nail, as shown at right. This will give the next layer of plaster something to hold onto.
Dampen the patch again and apply another layer of patching plaster to about 1/4 inch of the surface, as shown. Let the patch dry, sand it with fine-grade sandpaper wrapped around a sanding block, and apply a coat of finishing plaster. Sand, prime the patch with sealer, and then finish to match the wall.