Very tenacious adhesive and sealant for above and below the waterline. Our Quick Cure Polyurethane caulk is ideal for installing hardware and thru-hulls that require a solid, but flexible seal. When cured, this polyurethane caulk forms a strong, flexible bond to fiberglass, wood, painted surfaces, metals and plastics. This flexible quality maintains a seal when hardware is loaded; as is often the case with cleats being loaded by docklines. Thru-hulls benefit from the same flexible seal as bronze, stainless steel, and plastic expand at different rates than fiberglass and wooden hulls. We recommend masking hardware edges and surrounding areas to prevent contamination and reduce clean up times. For a bond and seal you can count on below or above the waterline, grab a tube of West Marine Polyurethane Adhesive Sealant. Key Features Forms strong flexible bond to fiberglass, wood, painted surfaces, metals and plastics Tack-free cure within 1 hour; fully cured in 24 hours Great for use above and below the waterline Sandable and paintable (after fully cured)Color: White 10.1 oz.