Bitumen Mastic is a trowel-applied, heavy-duty, thick, black, plasticised sealer and repair compound, which may be used to seal most roofing defects: roof screw bolts, nail holes, sheeting laps, valleys, gutters, down pipes, cracked tiles and many other roofing details. Bitumen Mastic has a built-in membrane so an additional membrane is generally not required. Bitumen Mastic is solvent-based and therefore not recommended for fish ponds or any drinking water applications. Bitumen Mastic can be used effectively for repair work if rain is imminent, as it is solvent-based. Not recommended where exposure to negative water pressure is present. Bitumen Mastic is flammable when wet. All necessary fire precautions should be taken. In areas were Bitumen Mastic is exposed to UV it is recommended to overcoat with Alu-Coat Silver (bituminous aluminium paint). Clean up with thinners, solvent or petrol.