Sika Black Jack 903 Fibre Reinforced Bitumen Trowel Mastic 1L 90301

Product Details: Brand: Sika | Range: Black Jack | Product Type: Fibre Reinforced Bitumen Trowel Mastic | Size: 1 Litre | Colour: Black | Product Code: 90301 | Model: 90301 | SKU: 486987 | MPN: 486987 852672 | Sika Code: 852672 | EAN: 5029347009311 | Barcode: 5029347009311

Sika Black Jack 903 Fibre Reinforced Bitumen Trowel Mastic 1L is a thick black bituminous repair mastic designed for trowel application. It is used for sealing, waterproofing and repairing small problem areas on suitable roofs, gutters, flashings and external building surfaces.

The 1 litre tin is the compact size in the range. It is best suited to small roof patch repairs, minor holes, short cracks, localised seams, gutter joints, downpipe joints and small flashing details where a larger tin is not needed.

Best For Small Roof Repair Jobs

This 1L version is useful when the repair area is limited and controlled application matters. It gives enough product for small maintenance jobs without opening a larger tin for a minor repair.

• Small cracks and holes in suitable roofing surfaces.
• Local roof felt, mastic asphalt and bitumen repair areas.
• Small gutter and downpipe joints.
• Minor flashing edges and chimney base details.
• Short seams, laps and joints on compatible roof materials.
• Small repair patches on suitable metal, concrete, timber and roofing surfaces.

Why Choose The 1 Litre Tin

Choose the 1L tin when the job is small, localised or occasional. It is the practical size for a quick repair around one section of roof, guttering, flashing or a small crack rather than a larger maintenance area.

For several repair points, a longer run of joints or a larger roof maintenance job, choose the 2.5L or 5L size from the side options. The 1L tin is the neat option for smaller patch repairs and controlled trowel work.

Key Benefits

• Compact 1L Tin: Good for small repairs, touch-in work and local problem areas.
• Fibre Reinforced Formula: Helps strengthen the repair and improve durability.
• Trowel Applied: Thick mastic consistency for pressing into cracks, joints, holes and gaps.
• Black Bitumen Finish: Suitable for compatible bitumen-based roofing and repair work.
• Ready To Use: No mixing required before application.
• Useful On Common Roof Materials: Suitable for many prepared roofing and building surfaces.
• Flexible Repair Compound: Designed to accommodate minor movement in the repaired area.
• Waterproofing Repair Use: Helps create a protective barrier on suitable prepared substrates.

Where It Can Be Used

Sika Black Jack 903 can be used for patching, sealing, bedding, bonding and waterproofing work on suitable prepared surfaces. Common uses include small holes and cracks in roofing felt, mastic asphalt, corrugated iron, cast iron, fibre cement, slates, lead, copper, zinc, concrete and timber.

• Roofing felt repairs.
• Mastic asphalt cracks and holes.
• Corrugated iron and fibre cement roof joints.
• Lead, copper and zinc flashing repairs.
• Small concrete and timber repair areas where compatible.
• Gutters, downpipes and pipe joints.

How To Apply

Always read the current Sika product data sheet and safety data sheet before use. The surface should be sound, stable, dry and free from loose material, dust, rust, grease and contamination before the mastic is applied.

• Step 1: Remove loose material, dirt, dust, rust and unstable coatings from the repair area.
• Step 2: Make sure the surface is dry and suitable before application.
• Step 3: Apply directly from the tin using a steel trowel, spatula or putty knife.
• Step 4: Press the mastic firmly into cracks, gaps, joints or holes.
• Step 5: Smooth the surface and extend the repair beyond the damaged area.
• Step 6: For larger gaps or weak areas, use a suitable reinforcing membrane where required.
• Step 7: Allow the repair to cure before exposing it to heavy use or further coating.

When To Choose A Larger Tin

The 1L tin is best for smaller patch repairs. It may not be the most efficient choice for several repair zones or larger roof maintenance work.

• Choose 2.5L: For several repair points, small roof sections or repeated maintenance work.
• Choose 5L: For larger trade repairs, broader patching areas and more frequent roofing work.
• Do not apply to wet surfaces: Surfaces should be dry and clean before use.
• Do not use as a structural repair: Loose, broken or unstable roof materials should be repaired properly first.
• Painting over is generally not recommended: Most coatings do not bond well to bitumen.

Technical Notes

• Fibre-reinforced black bituminous trowel mastic.
• 1 litre tin for small, localised repair work.
• Applied using a steel trowel, spatula or putty knife.
• Approximate coverage: 0.5m² per litre, depending on thickness and surface condition.
• Suitable for sealing, waterproofing, bedding, bonding and patch repairs.
• Can be used on many suitable prepared roof and building materials.
• Drying note: Sika advises that the mastic forms a surface skin after around 24 hours. The material underneath remains plastic for many months, which helps it tolerate moderate movement after application.

Products To Help With Preparation, Use Or Clean-Up

For dusty or loose repair areas, prepare the surface before applying the mastic. A scraper, brush or wire brush can help remove dirt, grit, loose material and unstable coatings from the repair area.

For porous, friable or difficult surfaces, a compatible bitumen primer may be needed before applying the mastic. Use Sika Black Jack 902 Bitumen and Flashing Primer 1L where priming is required.

For handling and clean-up, Sika Everbuild Heavy Duty Textured Wonder Wipes can help remove general grime, residue and dirt from hands, tools and suitable surfaces.

For larger repairs, choose the 2.5L or 5L Sika Black Jack 903 size from the side options.

• Specification

  Weight	0.45 kg
  Range	Black Jack
  Manufacturer	Sika
  Reference Code	90301
  Reference Code sika	852672
  Type	Bitumen Trowel Repair Mastic
  Size	1 Litre

• Product FAQs

  Q: What is Sika Black Jack 903 Trowel Mastic used for?
  A: It is used for sealing and repairing cracks, joints, holes, gutters, flashings, roof penetrations and local problem areas on suitable roof surfaces.
  Q: What size is this trowel mastic?
  A: This product is supplied in a 1 litre tin.
  Q: How is Sika Black Jack 903 applied?
  A: It is applied directly from the tin using a steel trowel, spatula or putty knife.
  Q: Can it be applied to wet surfaces?
  A: No. The surface should be clean, dry and free from grease, dust, rust, loose material and debris for best adhesion.
  Q: When should reinforcing fabric be used?
  A: Use reinforcing fabric for larger gaps, cracks, holes or weaker repair areas before applying a second coat.
  Q: How long does it take to dry?
  A: Sika states that the product takes around 24 hours to develop a surface skin, with the material below remaining plastic for many months.

• Downloads

  Sika Black Jack 903 Bitumen Trowel Mastic Technical Data Sheet
  Sika Black Jack 903 Bitumen Trowel Mastic Product Flyer
  Sika Black Jack 903 Bitumen Trowel Mastic Safety Data Sheet