Single component low modulus hybrid construction sealant

flexothane® 15 is a high performance low modulus moisture curing sealant. Based on hybrid technology it is both isocyanate and VOC free.

flexothane® 15 has a good cure rate, has excellent moisture and oxidation resistance, and exhibits excellent adhesion to cementitious, substrates, brick, stone, wood, and ceramic tiles. It has very low modulus and high elongation and is recommended for use in areas where extreme movement is anticipated.


flexothane® 15 can be used as a joint sealer and crack filler on cementitious surfaces and will provide a wide movement accommodation. It provides medium chemical, wear and corrosion resistance. A degree of colour change with time is to be expected.  It is not recommended for use in water retaining structures.

  • One-component, easy to gun
  • Low modulus
  • High elongation
  • Non-sag consistency
  • Isocyanate and VOC free
  • Non-tack/does not pick up dirt.
  • Good adhesion on the most common construction materials.
  • Good weathering and aging properties.
  • Can be applied vertically or horizontally
Typical Properties


100% Modulus (MPa) 0.25 – 0.40
Tensile Strength (MPa) 0.80 – 1.50
Elongation at Break ( % ) > 600 %
TVOC Complies
Density 1.4 (Cured)
1-2 Hours cure time
Skin Cure (dependent upon thickness, % RH and temperature) ± 2 mm per day
Skin Cure (dependent upon relative humidity and temperature)
Application Temp 5 – 35 °C
Service Temp 60 °C Dry
Storage Temperature <25 °C (higher temperatures will reduce storage life)
Movement capability 50% of initial joint width
Chemical Resistance Dilute acids, dilute alkali and general chemicals
Pack Size 600 ml sausage
Colour Grey, other colours against orders
Surface Preparation

All surfaces are to be clean sound and free of moisture, dust, laitance and oil.

Back-up material

Suitable back-up materials must be used to adjust sealant depth in the joint.  duracord is self-releasing material, but if durasheet, soft-board or cork has been used as the join filler and the sealant is going to applied without durcord a plastic strip bond breaker (polyethylene) must be placed on the filler surface before sealant is applied.


Place sausage in the barrel gun, cut end off of sausage and fit the nozzle; trim the tip to suit the joint spacing to be filled. Insert backing rod to the correct depth. Gun the product into clean joints that are free of loose material and laitance, then smooth with a dry spatula. The joint width should be designed to accommodate the expected movement, a width to depth ratio of 2:1 should b respected and a minimum width of 5 mm and a maximum of 20 mm should be adhered to (10 mm in depth).oil.


If applied to natural stone, we recommend the use of flexoprime® 105. If used in severe or damp conditions prime with flexoprime® 106.

Protection of adjacent surfaces

Masking tape applied to areas adjacent to the joint will protect them from contamination and enable the joints to be finished to a neat line. The masking tape should be applied after the joint has been prepared, prior to any priming or sealing operation and removed after all finishing and tooling operations have been completed, but before the sealant has cured.


Tooling of sealants is necessary to avoid air entrapment and to assist in wetting out the surfaces to which the sealant is applied.  The surfaces of the joint should be smoothed with a clean knife or spatula. A mild solution of liquid soap and water can be spraye onto the tooling spatula if required.

Painting over sealant

It is not recommended that a flexible sealant be over coated by less flexible coatings as joint movement will cause rupturing of the coating. The migration of plasticisers from the sealant into the coating could result in excessive dirt pickup.

Model specification

The sealant will be flexothane® 15, a single-component, low modulus moisture curing sealant that is isocyanate and VOC free applied in accordance with the recommendations of a.b.e.® 


Tools should be cleaned immediately after use, and before the material has set, with abe®super brush cleaner followed by washing with soap and water.


600 ml cartridges packed 12 per box.

Handling & Storage

This product has a shelf-life of 12 months if kept in a dry cool place in the original packaging. In more extreme conditions this period might be shortened.

Health & Safety

Uncured flexothane® 15 is toxic and should not be allowed contact with skin and eyes. The use of gloves and eye protection is advised. Splashes into eyes should be washed immediately wit plenty of clean water and medical advice sought. Ensure the working area is well ventilated during application and drying.  Always wear gloves when working with the material and avoid excessive inhalation and skin contact.
Cured flexothane® 15 is inert and harmless.

Important Note

This data sheet is issued as a guide to the use of the product(s) concerned. Whilst a.b.e.® endeavours to ensure that any advice, recommendation, specification or information is accurate and correct, the company cannot accept any liability for application – because a.b.e.® has no direct or continuous control over where and how a.b.e.® products are applied.

Further Information

Where other products are to be used in conjunction with this material, the relevant technical data sheets should be consulted to determine total requirements.

 a.b.e.®  has a wealth of technical and practical experience built up over the years in the company’s pursuit of excellence in building and construction technology.