Sikaflex-591 sealant

Looking for a versatile sealant for your boat? Sikaflex-591 is a multifunctional marine sealant specially developed for the demanding conditions encountered on the water. Whether you need to seal a joint above or below the waterline, Sikaflex-591 is suitable for a wide range of marine applications. Thanks to its excellent UV resistance, colour stability and mould-resistant properties, Sikaflex-591 is highly suitable for both interior and exterior applications.

Sikaflex-591 is based on Sika’s advanced STP (Silane Terminated Polymer) technology. The sealant is free from solvents, isocyanates, phthalates and PVC and complies with the requirements of the International Maritime Organization (IMO) for low flame spread.

Benefits of Sikaflex-591

• Excellent UV and weather resistance.
• Mould-resistant and colour stable.
• Suitable for both interior and exterior applications.
• Excellent adhesion to most substrates with minimal surface preparation.
• Free from solvents, isocyanates, phthalates and PVC.
• Suitable for use above and below the waterline.

• Complies with IMO requirements for low flame spread.

What is the difference between Sikaflex-591 and Sikaflex-291i?

We are often asked which marine sealant is the best choice. The main difference lies in their UV resistance.

• Sikaflex-591 is particularly suitable for exterior applications thanks to its excellent UV resistance and can be used indoors as well as above and below the waterline.
• Sikaflex-291i is also a versatile marine adhesive and sealant but has more limited UV resistance. For applications that are continuously exposed to UV radiation, Sikaflex-591 is therefore the better choice.

What is Sikaflex-591 used for?

Sikaflex-591 is a versatile sealant specifically developed for marine applications. It is ideal for creating flexible, vibration-resistant joint seals and offers a wide range of uses both above and below deck. It adheres well to many commonly used substrates in the marine industry.

Typical applications of Sikaflex-591 include:

• Bonding and sealing interior and exterior components.
• Flexible joint sealing.
• Sealing non-ferrous metals.

Directions for use

1. Surface preparation
   

   Ensure that the surface is clean, dry and free from grease, oil, dust and any other contaminants.

2. Priming
   

   Pre-treat the substrate with Sika Aktivator-205. For timber, ABS and non-ferrous metals, subsequently apply Sika Multiprimer Marine to achieve optimum adhesion.

3. Applying the sealant
   

   Apply the sealant using a standard cartridge sealant gun. The ideal application temperature is between 15°C and 25°C. Keep in mind that the skin formation time is approximately 35 minutes. Please note: if PU adhesives or other sealants have also been applied, allow them to cure for at least 24 hours before applying Sikaflex-591.

4. Finishing
   

   Tool the sealant joints smooth before skin formation occurs. For a smooth, professional finish, we recommend using Sika Tooling Agent N.

Specifications

Packaging: 300 ml cartridge (or 70 ml tube)
Colour: white, grey, black
Chemical base: silane-modified polymer
Cure mechanism: moisture curing
Hardness (Shore A): 45
Tensile strength: 2.2 MPa
Elongation at break: 500 %
Shrinkage: 1 %
Service temperature: -50 °C to +80 °C
Density (uncured): 1.5 kg/L
Non-sag properties: very good
Application temperature: between 5 °C and 40 °C
Open time: 20 minutes
Skin time: 35 minutes
Shelf life: 12 months (stored at temperatures below 25 °C)
Application gun: caulking gun for cartridges