Granville Black Instant Gasket & Silicone Sealer Sealant Flexible 40g Tube. This multi-purpose, waterproof adhesive sealant cures quickly, providing a permanently flexible, high-strength waterproof seal. It is designed for automotive and industrial applications and is suitable for sealing windscreen glass (not bonding), electrical connections, and sealing around light units and rear light clusters. The sealant is resistant to high temperatures up to 200°C and will not crack, harden, or dry out.