Paint fiberglass around the home by cleaning the surface, removing any hardware, sanding, applying a primer and applying the top coat. Use several thin coats of paint instead of one thick one for best results.
Clean the surface using an appropriate cleaner, such as trisodium phosphate. If preparing a bathtub or sink, use a soap scum remover. Acetone helps to remove oily or waxy stains from the surface. Rinse thoroughly after using each chemical.
Remove hardware from the surface before painting. This includes any grab bars, faucets or handles. Removing hardware gives the finished product a more professional look than taping around it. Remove any caulking from around the tub before painting.
Use epoxy putty to fill any deep gouges in the surface. Because you are painting the surface, you do not need to match the putty to the existing surface. Sand the putty so it is smooth with the surrounding surface.
Use 80-grit sandpaper to roughen the surface so the paint adheres well. Use masking tape around the edges, where the fiberglass meets the wall.
Apply an oil-based bonding primer to the surface. Have the primer tinted to match the top coat. Once the primer is dry, apply a thin top coat. Repeat with several other thin top coats. Replace any fixtures or trim, and caulk the joints where the fiberglass meets other building materials.