Dowsil Firestop 400 is an intumescent acrylic sealant for internal applications. Developed to maintain the integrity of fire walls or partitions, it does not emit halogenated by-products under fire conditions. Resists mildew and mould growth. Tested to BS 476 Part 22 1987 and BS 476 Part 7 1987. A 2 hour fire rating can be achieved.