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One flexible sealant can cover a wide range of straightforward joints and bonding tasks—provided the substrates are suitable. Sikaflex®-221 is a one-component polyurethane adhesive sealant used for permanent elastic sealing and light bonding in vehicle, equipment and general fabrication work.
Elastic sealing across mixed materials
Sikaflex-221 adheres to many prepared metals, two-component paint systems, ceramics and suitable rigid plastics. Its non-corrosive, low-odour formulation is useful for interior sealing and assembly jobs where the joint may later be sanded or painted after curing, subject to coating compatibility.
Choose it for the joint—not just the material
It is a versatile elastic adhesive sealant, but not every plastic, fuel exposure or chemical environment is suitable. Sika advises testing materials prone to stress cracking, and the product is not resistant to several aggressive solvents, fuels and concentrated chemicals. For marine-specific general sealing, compare Sikaflex-291, which is positioned for boatbuilding applications.
Check the current Sika surface preparation guidance, cure conditions and material compatibility before use. Professional substrate trials are recommended.
Sikaflex®-221 Physical Properties
| Property | Value |
|---|---|
| Base | One-component moisture-curing polyurethane |
| Typical application temperature | 5°C to 40°C |
| Skin time at 23°C / 50% RH | Approximately 60 minutes |
| Open time | Approximately 45 minutes |
| Shore A | 40 |
| Tensile strength | 1.8 MPa |
| Elongation at break | 500% |
| Shrinkage | Approximately 5% |
| Service temperature | −50°C to +90°C |
| Shelf life | 12 months unopened below 25°C |