Rust-Oleum Marine Coatings Primer for Wood & Fiberglass is suitable for use as a base coat whenever the surface to be painted is aged, cracked, checked, pitted or rough. This primer can be applied to fiberglass, wood and previously painted surfaces. It dries quickly and is easy to sand. It provides a smooth base that allows Rust-Oleum Marine Coatings Topside Paint to dry to a uniform gloss and appearance.