Bostik Bituminous Mastic for Roofs is a multi-purpose trowel grade bituminous material for waterproofing, stopping, bedding, pointing and sealing. It can be applied to mastic asphalt, roofing felt, corrugated iron, cast iron, fibre cement, slates, lead, copper, zinc, concrete and timber. It dries to a flexible black material, which remains soft and pliable for a long time after application.