Bondo® Liquid Resin for Fiberglass is a high-strength polyester resin that can be used with fiberglass mats or cloths on surfaces including fiberglass metal wood and masonry. This all-purpose material is used to repair breaks and recreate or join surfaces. It can also be used by itself as a wood or concrete sealer. The 100% waterproof two-part resin includes clear liquid hardener and can be used to repair cars trucks pools showers boats and more.