18 Perfectseal Flashing Cement is a scientifically compounded composition of selected asphalts, mineral fibers, and refined solvents that are manufactured to a heavy consistency. Designed for application by trowel 18 is a durable cement with excellent adhesion and weathering characteristics. This product when applied dries to a tough, flexible, water resistant and corrosion proof coating that provides excellent performance over a wide range of temperature and weather conditions. Available in three consistencies: Summer, Semi and Winter.