Megaprene 40 - Gun Grade Polyurethane Joint Sealant 600ml


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Megaprene 40 is a single-component, gun grade, moisture-curing polyurethane construction sealant. It is tough, durable, and offers good chemical resistance, including resistance to intermittent fuel spills. Megaprene 40 is highly flexible, non-sag, fast curing, and paintable. It has excellent adhesion to most common building materials and is suitable for vertical and horizontal joints in bridges and roadways, car parks, driveways, factory and warehouse floors, and service station driveways.

Product Characteristics

  • Colour: Concrete Grey
  • Size: 600ml


  • Highly flexible
  • Non-sag
  • Fast curing
  • Paintable
  • Tear resistant
  • Excellent adhesion to most common building materials

Joint Preparation

Ensure that the substrates are sound, clean, and free from contamination. If necessary, prime the substrate with the appropriate primer for the substrate.


Priming is recommended for concrete floor joints using Primer 2001. For suspect surfaces, adhesion testing is recommended. Apply the correct primer when required and allow it to dry.

Backer Rod

Use Adhefoam open cell backer rod where required. Closed cell backer rod can also be used, but care must be taken not to damage the outer skin of the rod as it can cause gassing (bubbles) in the sealant. When the depth of the joint does not allow for backer rod, a bond breaker tape is required to prevent three-sided adhesion.


Fill the prepared joint completely, taking care not to trap air, as entrapped air may cause bubbles in the sealant. Dry tool immediately before the sealant skins. The tooling time is a minimum of 10 minutes, depending on temperature and humidity. The joint depth must be half the depth of the width, with a minimum depth of 10mm.


Not suitable for internal swimming pool applications.


Megaprene 40 is paintable with most commonly available paints. Testing is recommended. It must be fully cured before applying paint. Failure to do so can result in retarding the curing of the polyurethane sealant and the paint topcoat, resulting in a tacky surface.


Uncured material can be removed using industrial-strength solvents such as Xylol or mineral turps.

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Megaprene 40 - Gun Grade Polyurethane Joint Sealant 600ml

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