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Owl Roof Lava20 PU Mastic

Owl Roof Lava20 PU Mastic

Best Uses

Owl PU Mastic is suitable for sealing joints in metal frames, aluminium windows and panels, glass, granite and marble or for flooring applications.

Owl Roof Lava20 PU Mastic is a fast curing joint sealant, general purpose adhesive that has been specifically formulated to contain both PU and silylated PU technology. Due to the nature of the sealant formulation, it includes the best properties of both technologies. The material has been modified in order to give enhanced thixotropic properties.

  • Excellent adhesion on almost any type of surface, with or without the use of special primers

  • Excellent extrusion, tooling and storage stability over wide range of climatic conditions

  • Excellent chemical resistance, suitable for sealing joints in swimming pools and chemically treated water

  • Micro-organism and fungus resistant

  • Application under water immersion possible

  • Excellent heat resistance, suitable for application where exposure to temperatures > 60°C take place

  • Resistance to cold: The sealant remains elastic even down to -40ºC.

Owl Roof Lava20 PU Mastic cures rapidly through reaction with atmospheric humidity to produce a sealant with excellent early grab adhesion even on substrates traditionally problematic for PU sealants, such as aluminum, steel, polycarbonate etc.

Additionally, the sealant has been modified in order to have extrusion profile identical to Hybrid PU or MS technology.


Clean joint thoroughly, and ensure that no oil, grease and wax contaminants, silicone remains are present. For many applications, primer is not required. In the case
of application on very porous substrates, bond area surfaces thoroughly to avoid the possibility of air bubbles being blown into the uncured sealant if the substrate temperature rises. The recommended primer is Owl Lava Prime.

Apply backing material such as open cell polyurethane or a closed cell polyethylene backing rod. Although both types of backing rod are recommended care must be taken when using the closed cell polyethylene rod that the outer skin not be punctured as in rising temperature conditions it may cause bubbling. Backing rod application is important as it ensures that the correct width to depth ratio is achieved provides a firm backing against which the sealant can be tooled off.

Slide the sealant into the applicator gun, cut off the very end of the sealant packaging and fit the gun with the nozzle that has been cut to deliver the right bead size.

Extrude the sealant into the joint ensuring that no air is trapped in the joint. Wide joints will require more than one pass of the application gun to make sure that sealant is in full contact with the sides and bottom of the joint. Tooling is recommended immediately after the application of sealant.

The ratio width to depth should be 2:1 subject to a minimum depth of 10mm.