Sika Black Jack 903 Bitumen Trowel Mastic

Everbuild Black Jack 903 Bitumen Trowel Mastic is a trowel-applied, black, heavily-filled bituminous compound reinforced with fibres. It forms a surface skin while the mass below remains permanently soft to accommodate moderate structural movement — ideal for sealing and filling holes, cracks and defects where some flexibility is needed. Suitable for use on mastic asphalt, roofing felt, corrugated iron, metal guttering and downpipes, and for pointing up ridge tiles, slates and flashings. Can be reinforced with a glass fibre bandage for bridging larger gaps or damaged sections. Prime surface with Black Jack 902 Primer and overcoat with Black Jack 905 All Weather Roof Coating for a durable, long-lasting repair system.

Benefits

• Trowel-applied for precise placement in cracks, holes and at flashings and junctions
  
• Fibre reinforcement bridges small gaps and provides additional structural integrity
  
• Remains permanently flexible below the surface skin, accommodates thermal movement without cracking
  
• Multi-substrate, suitable for asphalt, felt, corrugated iron, metal guttering, ridge tiles and slates
  
• Can be combined with glass fibre scrim for reinforcement over larger damaged areas
  
• Part of the Black Jack system, works with 902 Primer and 905 Roof Coating for a complete repair

Good to know

• Ensure surfaces are dry and free from loose debris and algae before applying
  
• Prime concrete and porous surfaces with Black Jack 902 Primer and allow to dry
  
• For additional reinforcement on larger defects, embed a glass fibre bandage into the fresh mastic before it skins
  
• When dry, overcoat with Black Jack 905 All Weather Roof Coating for a complete, weatherproof finish
  
• In cold weather, store in a warm area overnight before use to improve workability
  
• Clean tools with white spirit immediately after use