Bond It Trowel Mastic Fibre Filled Bitumen Paint Roof Repair Compound 1/2.5/5L Description: A heavily filled and fibrated bituminous compound that dries to a soft flexible black coating which remains soft and pliable for a long time after application. Uses Bond It TROWEL MASTIC is a multi-purpose trowel grade material for waterproofing, stopping, bedding, pointing and sealing. TROWEL MASTIC can be applied to mastic asphalt, roofing felt, corrugated iron, cast iron, fibre cement, slates, lead, copper, zinc, concrete and timber. Preparation All surfaces must be structurally sound, clean, dry and free from surface contaminants such as grease, rust and dirt. If necessary, remove any organic growth i.e. lichen, with a fungicidal wash such as Bond It MOULD STOP. .