BentoSeal is trowel-grade, sodium bentonite/ butyl-rubber based Sealant designed for a variety of surface preparation and waterproof detailing work with Volclay Panels, Swelltite and Voltex waterproofing membranes. Being bentonite based, BentoSeal swells upon contact with water to Seal against water intrusion. With the consistency of thick grease, it is easy to apply and bonds to most substrate materials.