Koster MS Joint Sealant

Koster MS Joint Sealant

Koster MS Joint Sealant is a high-performance waterproofing solution.  This highly elastic MS polymer-based waterproofing material with excellent elasticity, is characterised by high UV and weather resistance and excellent adhesion to various interior and exterior building materials.

Koster MS Joint Sealant exhibits superior characteristics, being fast-curing and highly elastic.  This one-component product is UV-resistant, ensuring durability even under extreme application conditions.  Notably, it is VOC-free and environmentally friendly, demonstrating commitment to sustainability.  Koster MS Joint Sealant combines the positive properties of silicone and polyurethane sealants without their characteristic weaknesses. It is free of silicone, solvents, and isocyanates and therefore does not release CO2 during curing. As a result, the material remains bubble-free when it comes into contact with damp surfaces. It also forms a
strong bond on damp surfaces.

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Koster MS Joint Sealant

Can be used for all types of joints in the area of windows and doors in building construction and other construction areas such as

  • Joints in concrete and brick components
  • Joints in the area of various building elements
  • Joints around roof installations
  • Comparable joints in building construction and other components

Due to its excellent adhesion to most substrates (including masonry, concrete, screed, PVC-U (rigid PVC), PP, PE, FRP, plastics and metal
(except copper) and its high elasticity, it is not only ideal for sealing joints of almost all types in the construction industry, but also against
the attack of various chemicals.

  • Highly elastic
  • Good workability
  • Environmentally Friendly
  • Ready-to-use material (1 component)
  • Seamless waterproofing layer with easy application
  • Highly viscous consistency for slopes and vertical surfaces
  • Adhesion to various substrates
  • Excellent weather and UV resistance
  • Environmentally friendly product – can be used on a wide variety of surfaces
  • Retains its properties at installation temperatures between -30°C and +80°C
  • Resistant to oils, seawater, cleaning agents and various chemicals
  • Resistant to hydrolysis, salts and frost
  • Solvent-, silicone-, water-, bitumen- and isocyanate-free
  • No shrinkage due to solvent leakage during curing
  • No cracking due to shrinkage during curing
  • Can be applied in greater thicknesses than solvent-based sealants
  • Safe for workers and the workplace, does not produce toxic fumes
  • Does not react with moisture to form carbon dioxide
  • Allows application to slightly damp substrates
  • Does not form bubbles and voids that can lead to cohesive failure


Product Details
Koster MS Joint Sealant
Product Code:
600 ml foilbag
light grey (approx. RAL 7040)
350 x 103 mPa.s
Density (+20 °C):
approx. 1.5 g/cm³
approx. 500 %
Pasty, stable
Skin forming time
2-3 h/mm (according to weather conditions)
Rain resistant (+23 °C/65 % rLF)
within approx. 30 Min.
Curing time (+23 °C/65 % rLF):
Min. 8 h - max. 24 h
Application temperature:
+5°C - +35°C (Air temp.)
Operating temperature:
-30 °C - +80 °C
Max. Expansion:
Technical Drawings

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