Q: I need to patch a hole in the wall plaster caused by a doorknob. The hole is only a few inches in diameter and the lath is intact. Will a little spackling paste do the trick?
A: For plaster repairs, use a powder-based product called plaster patch, which has adhesives that bond with the existing plaster. Repairing plaster takes patience because the product must be applied in thin, successive layers (1/8 to 1/4 inch). To avoid cracking, each coat must be completely to dry before the applying the next. Before applying the first coat, remove any loose plaster and undercut the edges of the hole as it approaches the lath so as to better anchor the patching plaster. Prep the damaged area by soaking with water, then mix the patch product smooth and use a putty knife to apply the first coat. Score the wet compound with a nail for better adhesion of the second coat. Allow to dry and apply the next coat. Continue the process until the hole is filled, feathering the edges of the final coat. Sand lightly to smooth the patch.