Small holes in plaster are easy to repair, providing the lath backing that held the original plaster is still intact. If it is, simply mix joint compound with plaster of Paris and use it to fill the hole (the compound retards the plaster setting time and makes it easier to work with).
Clean away any loose plaster and dust and fill from the edges in, working the plaster mix into and through the lath for a good bond. Do one rough, or “scratch,” coat and allow it to dry, then apply a finish coat.
If you must repair a hole in a plaster wall where there isn’t a backing that will hold the plaster from behind, you’ll have to install backing first.Enlarge the plaster hole just enough to reveal some remaining well-anchored lath. Cut a piece of wire mesh to fill the opening, push the mesh into the hole and hold it in place with wire ties wound around one or two dowels or sticks.
Apply the plaster/compound mix in layers, allowing each to set hard before adding another. When the last layer is dry, simply snip off the wire. If the hole is large but your plastering skills aren’t, use only joint compound for the finish coat. When dry, sand smooth, prime, and paint.
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