Plaster is a material used in several applications, including siding, interior and exterior walls, and decorative pieces. Outdoor plaster statues are used to adorn gardens and lawns of several homes. Unfortunately when plaster becomes exposed to humidity and moisture it can begin to degrade and pieces of the statue will eventually begin to fall off. It is possible to waterproof an outdoor plaster statue in order to preserve it and protect it from the elements for several years to come.
Sand the surface of the plaster statue lightly with fine-grit sandpaper. Wipe away any dust created by the sanding with a soft cloth.
Cover the entire statue with a light coating of linseed oil, using a paintbrush.
Allow the first coat to linseed oil to dry and apply a second and third coat, allowing each additional coat to dry before the next coat's application.
Allow the final coat to finish drying before placing the statue in an outdoor environment.
Avoid covering the statue with heavy layers of linseed oil, which could cause the finished product to take on a greasy, unfinished appearance.