Composed of fiberglass, false rocks are generally used to create veneers, fences and walls. Unlike actual rocks, which are generally rough enough to support durable painted finishes, fake rocks do not hold lasting finishes well because they're nonporous and smooth. Professionals abrade false stones to improve their ability to support primer bases. Unless you want finish failure in the form of flaking, employ the same technique. Finish the fake rocks with the right type of paint based on their location, or the finish could fade and/or crack.
Instructions
1. Scrub the fake rocks with a water-based soap, using a sponge. Rinse the false stone with wet rags or a hose. Let the fake rocks dry for three hours.
2. Abrade the fake rocks, or long-term adhesion will prove unlikely. Sand each false stone until it feels rough.
3. Apply painter's masking tape to surfaces adjacent to the fake rocks. Position canvas drop cloths beneath the fiberglass structure.
4. Coat the fake rocks with the correct type of primer, using a mini-roller. Use latex primer on interior fiberglass stones; use acrylic primer on exterior stones. Roll vertically, smoothing runs before they begin to dry. Immediately touch up the false stones, using a 3- to 4-inch nylon paintbrush. Let the fiberglass rocks dry for three hours.
5. Wash the mini-roller and brush three times using water.
6. Paint the fake rocks just as you primed them. Use latex paint on interior fiberglass stones; use acrylic paint on exterior stones. Let the fiberglass rocks dry for three hours.
