Plaster has a tendency to crack as a home moves, whether from earthquakes or natural settling. Fine cracks, nail holes, and small gouges usually can be repaired with spackling compound.

Widen hairline cracks to about 1/8 inch with the tip of a lever-type can opener; blow out the debris. With your finger or a putty knife, fill the crack with spackling compound. Sand the compound in a circular motion when dry, using a block wrapped with fine-grade sandpaper. Prime the patch with sealer.

For large cracks, knock out any loose plaster with a cold chisel and ball-peen hammer. Clean out the plaster in and behind the lath to provide a surface to which the new plaster can adhere. Brush the area clean, and dampen it with a sponge for better adhesion.

If the hole is smaller than 2 inches across, fill it with a single layer of patching compound, and finish as described below. For larger holes, apply a first layer using a 6-inch broad knife.

Score the patch with a nail, and then allow the surface to dry. Moisten the patch, and then apply a second layer of patching compound, coming within 1/8 to 1/4 inch of the surface. Score the patch, and let it dry.

Apply the final coat, feathering the edges an inch or so beyond the edges of the hole. Scrape a straightedge across the wet finish coat to remove any excess material. When the patch is dry, sand and spot-prime.

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