This high-strength polyester resin creates waterproof repairs on metal, fiberglass and wood as well as seals concrete and rotted wood. Use it to join surfaces together while creating a strong, waterproof and long lasting bond. This product can be used with Bondo fiberglass cloth or mat to create a stronger repair and is sandable in less than 2 hours. Waterproof and compatible with all paints, including gel coat and marine paints.