Fast Cure, Durable Repairs Dynatron Liquid Hardener creates a chemical reaction with polyester fiberglass resin for a fast cure and a strong, durable repair. Used as part of a 2-part system, the liquid hardener is mixed with fiberglass resin to create extremely strong, durable and waterproof repairs. Once mixed, the fiberglass resin will cure quickly. Recommended for Automotive and Household Repairs This liquid hardener is a versatile product for use with most repairs involving polyester fiberglass resin. It is an ideal choice for automotive restoration projects. It may also be used for interior and exterior home repairs, including tubs, showers,sinks, pools, hot tubs, boats and more. Easy to Dispense The liquid hardener is packaged in a tube for easy dispensing. It allows you to control the amount of hardener that you want to add to the fiberglass resin for an optimal ratio.