3M 4200 Polyurethane Fast Cure Adhesive-Sealant 10oz White 3M Fast Cure Marine Sealant is a one-component, medium-strength, moisture-curing, gap-filling polyurethane that delivers strong flexible bonds to aluminum, wood, gelcoat, and fiberglass. It forms a watertight, weather-resistant seal above and below the waterline. Its flexibility allows for dissipation of stress caused by shock, vibration, swelling, or shrinking. This sealant is recommended for the following applications fiberglass deck t