Hyperseal 25 LM-S®


Unique one component, polyurethane-based, low modulus joint sealant, combining classic polyurethane technology with hybrid technology, with outstanding thixotropic properties


Hyperseal 25 LM-S is a novel low modulus expansion joint sealant, especially formulated to contain both PU and silylated-PU technology, thus giving rise to a sealant which includes the best of both technologies. It has been modified in order to give enhanced thixotropic properties. It cures by reaction with atmospheric humidity to produce a joint sealant with a 50% joint movement accommodation factor and excellent adhesion on substrates traditionally problematic for PU sealants, e.g. glass, aluminum, steel, polycarbonate, etc.. Additionally, the sealant has been modified in order to have extrusion profile identical to hybrid PU or MS technology. The extrusion rate and tooling of the sealant remain the same throughout a very wide range of temperature and humidity conditions.


The sealant is easy to apply even in very low temperatures and the storage stability is unlike any polyurethane sealant in the market.


Complies to:

  • ISO – 11600

  • Typ F – Klasse: 25LM

  • DIN 18540-F

  • ASTM C 920

  • US Federal Specification TT-S-00230C

  • Type II Class A


Recommended for:

Sealing joints in:

  • Insitu concrete,

  • expansion concrete plates,  

  • precast panels,

  • brick and block work,

  • water tanks and swimming pools,

  • metal frames,

  • aluminum windows and panels,

  • irrigation channels,

  • glass,

  • granite & marble.


Shelf life:

12 months minimum in the original packaging when stored in dry places and at temperatures of 5-25°C. Once opened, use as soon as possible.



300cc Cartridges

600cc Sausages




Features & Benefits

  • 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.

  • Low modulus, joint movement accommodation 50%.

  • Microorganism and fungus resistant. 

  • Application under water immersion possible.

  • Resistance to cold: The sealant remains elastic even down to -40 °C.
  • Excellent heat resistance, suitable for application where exposure to temperatures >60°C take place.




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 MICROPRIMERTM. 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.


For further details please refer to the


Technical Data Sheet:

Adobe PDF file icon 32x32


Hyperseal 2