Sikaflex®-291 Marine Adhesive Sealant Multifunctional, IMO-Compliant
Sikaflex®-291 is a non-sag, 1-component polyurethane sealant developed for the marine market. It cures on exposure to atmospheric moisture to form a durable, elastic seal. Engineered for demanding on-board environments, Sikaflex®-291 meets International Maritime Organization (IMO) requirements and is suitable for a wide range of sealing and light bonding tasks above and below deck.
Why Choose Sikaflex®-291
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Excellent adhesion to common marine substrates
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Good ageing & weathering resistance for long service life
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Elastic to absorb vibration and movement
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Low odour and non-corrosive
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Overpaintable and sandable after cure*
- Available colours: White, Grey, Black
*Always test paint compatibility. Paint elasticity is typically lower than sealant elasticity and can crack in the joint area.
Typical Uses
Multipurpose sealing and light bonding in marine construction, including elastic, vibration-resistant joints and interior sealing applications.
Suitable Substrates
- Wood
- Metals, metal primers and 2-component paint systems
- Ceramic materials
- Plastics such as GRP (fibreglass), etc.
Do Not Use On
- Plastics prone to stress cracking (e.g. acrylic/Plexiglas®, polycarbonate)
Professional users only. Always test with actual substrates and site conditions to confirm adhesion and compatibility.
Technical Data (Typical)
| Property |
Method / Note |
Value |
| Chemical base |
— |
1-component polyurethane |
| Cure mechanism |
— |
Moisture-curing |
| Colour |
CQP001-1 |
White, Grey, Black |
| Density (uncured) |
— |
~1.3 kg/L (colour-dependent) |
| Non-sag properties |
— |
Good |
| Application temperature |
Ambient |
5 – 40 °C (optimum 15 – 25 °C) |
| Skin time |
CQP019-1 (A) |
~60 minutes |
| Open time |
CQP526-1 (A) |
~45 minutes |
| Curing speed |
CQP049-1 |
Depends on temperature & humidity (see TDS) |
| Shrinkage |
CQP014-1 |
~5 % |
| Shore A hardness |
CQP023-1 / ISO 48-4 |
~40 |
| Tensile strength |
CQP036-1 / ISO 527 |
~1.8 MPa |
| Elongation at break |
CQP036-1 / ISO 527 |
~500 % |
| Tear resistance |
CQP045-1 / ISO 34 |
~6 N/mm |
| Service temperature (continuous) |
CQP513-1 |
−50 to +90 °C |
| Service temperature (short-term) |
CQP513-1 |
+160 °C (4 h), +180 °C (1 h) |
| Shelf life |
(B) |
12 months (store < 25 °C) |
CQP = Corporate Quality Procedure. (A) 23 °C / 50 % r.h. (B) Storage below 25 °C.
Application Guidance
Surface Preparation
Substrates must be clean, dry, and free from grease, oil, and dust. Surface treatment depends on the substrate and is crucial for durability. Refer to the current Sika® Pre-treatment Chart for Marine Applications and verify with tests on original substrates.
Application
- Process between 5 °C and 40 °C; reactivity and handling change with temperature and humidity.
- Optimum substrate and product temperature is 15 – 25 °C.
- Apply with hand, pneumatic, or electric piston guns, or suitable pump equipment.
Tooling & Finishing
- Tool within the skin time.
- Recommended finishing agent: Sika® Tooling Agent N (test any alternative agent for suitability).
Cleaning & Removal
- Uncured material: remove from tools/equipment with Sika® Remover-208 or a suitable solvent.
- Cured material: remove mechanically (e.g. knife, wire, abrasion).
- Skin/hands: clean immediately with Sika® Cleaner-350H towels or an appropriate industrial hand cleaner and water. Do not use solvents on skin.
Overpainting
- Best painted after skin formation; performance can be improved by treating the joint surface with Sika® Aktivator-100 or Sika® Aktivator-205 before painting.
- If the paint requires baking > 80 °C, allow the sealant to fully cure first.
- Always conduct preliminary trials under manufacturing conditions.
- Avoid using enamel, alkyd, and chlorinated rubber paints on the joint area.
Compliance & Approvals
- Meets requirements set out by the International Maritime Organization (IMO).
- Associated with the marine “Wheelmark” conformity mark under the Marine Equipment Directive (MED) where applicable.
FAQs
Can Sikaflex®-291 be overpainted?
Yes, once cured and after preliminary testing for compatibility. Note that paint elasticity is usually lower than the sealant’s and may crack over the joint. Enamel, alkyd, and chlorinated rubber paints should not be used on the joint area.
What is a “marine grade” sealant/adhesive?
Sika’s marine range is designed for flexible, waterproof, and durable assemblies across vessels from small yachts to large ships, for maintenance and construction tasks above and below the waterline.
When and why should a primer be used?
Primers promote adhesion on certain substrates. Sika® Primer-210 is commonly used prior to applying 1-component polyurethanes like Sikaflex®-291. Always confirm with testing.
What does the Wheelmark indicate?
The Wheelmark symbolizes conformity with marine equipment standards under the EU Marine Equipment Directive (MED).
Which substrates does Sikaflex®-291 bond to?
Wood; metals, metal primers and 2-C paint systems; ceramics; and plastics such as GRP. Avoid plastics prone to stress cracking (e.g. acrylic/Plexiglas®, polycarbonate).
How do I remove Sikaflex®-291?
Uncured: Sika® Hand Wipes or Sika® Remover-208 for tools/surfaces. Cured: mechanical methods (knife, wire, abrasion). Remover-208 will not remove cured material.
Important: Information above is based on typical data. Performance depends on substrate, preparation, joint design, and application conditions. Conduct on-site tests to verify suitability. Always consult the latest Technical Data Sheet (TDS) and Safety Data Sheet (SDS).
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