Browse durable mastic, duct tapes, and sealants at F.W. Webb. These sealants and foil tapes are used in indoor and outdoor duct systems to help them withstand changes in temperature and to cover and seal insulation. Use our convenient filters to sort sealants and tapes by size, material, finish, and length. Explore top-quality mastic, duct tapes, and sealants from trusted makers, including Shurtape, 3M, Ductmate, Hardcast, and Durodyne, to find the right fit for an existing system.