XtraBond 250 is a 100% acetoxy-based, one-component, mildew-resistant silicone sealant that promises to be permanently flexible. The sealant can be used in high-moisture areas, such as baths, as well as in areas near food preparation and storage, according to the manufacturer. XtraBond 250’s antimicrobial formula is NSF approved and FDA compliant. We found a 10.1-ounce tube online for about $5. premierbuildingsolutions.net