Sikaflex®-291i
Sikaflex®-291i is a non-sag, one-component polyurethane sealant, specifically developed for the marine sector. It cures using atmospheric moisture to form a highly elastic sealant that meets the International Maritime Organisation (IMO) low-spread-of-flame requirements and is Wheelmark-approved for marine safety standards.
Key Features
Wheelmark-approved for use in marine environments.
One-component, moisture-curing formulation—no mixing required.
Highly elastic, providing vibration resistance and long-term seal durability.
Low odour and non-corrosive, ideal for enclosed and sensitive environments.
Solvent-free, very low VOC, and with low isocyanate content, making it environmentally friendly.
Paintable and sandable, allowing for an aesthetic, finished surface.
Excellent adhesion to common marine materials like wood, metal, primers, 2-pack paints, ceramics, and GRP—but not suitable for stress-cracking plastics like PMMA or PC.
Technical Specifications | |
| Property | Specification |
| Base Chemistry | 1-component polyurethane |
| Colors Available | White, Grey, Black, Brown |
| Density (uncured) | ~1.3 kg/L (varies by color) |
| Non-sag Properties | Good |
| Application Temp | 10 °C to 40 °C |
| Skin Time | ~60 minutes at 23 °C / 50 % RH |
| Open Time | ~45 minutes |
| Shrinkage | ~2 % |
| Shore A Hardness | ~40 |
| Tensile Strength | ~1.8 MPa |
| Elongation at Break | ~700 % |
| Tear Resistance | ~7 N/mm |
| Service Temperature | –50 to +90 °C continuous; up to 120–140 °C short-term |
| Shelf Life | ~12 months (when stored below 25 °C) |
Applications
Sikaflex®-291i is engineered for a broad range of marine applications, including:
Elastic, vibration-resistant joint seals across vessel structures.
Interior and exterior sealing tasks on boats, including wood, metal, and GRP materials.
Used in shipbuilding, boat refurbishment, and marine interiors, providing durable performance in harsh environments.
Safety & Handling
Surface Preparation: Ensure surfaces are clean, dry, and free from grease or dust. For optimal adhesion, refer to Sika’s Pre-treatment Chart.
Application: Use caulking guns (manual, pneumatic, or electric). Finish tooling within the skin time using Sika® Tooling Agent N or a suitable alternative.
Removal: Clean uncured product with Sika® Remover-208; cured sealant can only be removed mechanically. Do not use solvents on skin.
Overpainting: Paint only after skin formation; test for paint compatibility beforehand.
Chemical Resistance: Resistant to fresh water, seawater, diluted acids, and caustics; limited resistance to fuels, oils, and fats; not compatible with organic solvents or high-strength acids.
