Generally, acetone is a great cleaning solvent that is commonly used on metals, wood, fiberglass, epoxy, polyester resin, and glass to remove contaminants, dirt, grease, wax, and oils. Acetone has also been used as a thinner for gelcoat, commonly for spray applications. Acetone should not be used on 1-part paints or varnish coatings, clear windows, lenses, or clear plastics.