FlexSeal

Flex Seal® Liquid Rubber Sealant Coating is a thick rubberized liquid that you can brush, roll, dip or pour. It starts out as a thick liquid and dries to a strong, flexible, watertight, rubberized coating. Seals out air, water and moisture and is mildew, chemical and UV resistant. Non-hazardous, non-flammable and safe around plants and animals. Black. 32-oz. can.