Plaster statues are initially shaped with wire and then thick coats of plaster are applied over the wire frame to form the statue. Plaster absorbs liquid easily; therefore, special care must be taken to seal the plaster prior to painting. The entire process only requires a few materials and some time to complete it successfully.
Seal your plaster statue with a sealant using a paint brush. Various types of sealants exist for plaster, including PCV and polyurethane; however, if your statue will be exposed to outdoor elements or humidity, it is best to seal it with polyurethane, using a brand that is made for exterior painting. Verify that the polyurethane you select indicates on the label that it is weatherproof. Allow the first coat of polyurethane to dry completely.
Apply two more coats of polyurethane to the statue, allowing each coat to completely dry in between applications. You should have a 1/4-inch coating of polyurethane on your statue when you have completed sealing it.
Sand down any bubbles or uneven areas in the polyurethane coating using a fine grain, 150 to 180 grit sandpaper. If sanding is necessary, apply one more thin coat of polyurethane over the entire statue using a paint brush. This will make the top layer as smooth as possible for painting.
Paint the base colour on your statue using a paint brush and acrylic paint. This will be the primary background colour for your statue and should cover the entire statue. Allow the paint to dry.
Paint the features on your statue with acrylic paint and a paint brush. Features include eyes, clothing, leaves or whatever distinctive elements exist on your statue. Allow the features on your statue to dry completely.
Paint in shadows and highlights on your statue. Use acrylic paint and a paintbrush or sponge to add shadows and highlights. Mix one part black acrylic paint with one part water and dab your brush or sponge in the mixture; lightly apply it to the statue to create shadows. The more you apply, the darker the shadows will become. Allow the highlights and shadows to dry completely.
Apply one more coat of polyurethane over the painted surface of the statue, being careful to paint in even strokes with your brush, so there are no bubbles in the polyurethane. Allow the polyurethane to dry completely.
Drying times for paint or polyurethane on plaster will vary. Humidity, cold climates and excessive heat can cause drying times to be as long as one to two weeks.