Flex Paste White is a super thick rubberized paste you spread, shape and form to seal large gaps, cracks and holes. It starts out as a thick paste and dries to a strong, flexible rubber coating that seals out air, water and moisture, and it clings to hard-to-reach areas where a liquid would run. This 12 lb. container covers approximately 10 linear ft. at 2 in. wide and 1/16 in. thick per pound. Apply in thin layers with a trowel or putty knife, allowing 24 hours to cure between coats. It forms a skin within 15 to 30 minutes and fully cures within 24 to 48 hours, getting stronger over time as it reacts with air and moisture. Flex Paste can be applied to wet surfaces and even underwater, and it will not dissolve. Once cured it holds a matte white finish that can be painted, shaped and molded to match the surrounding surface. It expands and contracts with the substrate, never shrinks or cracks, withstands temperatures from minus 40°F to 200°F, and resists UV, chemicals and mildew. Sanding is not recommended.