Bostik Seal ‘N’ Flex One Plus P590 Polyurethane Sealant 600ml

Bostik Seal 'N' Flex One Plus P590 is a low-modulus polyurethane sealant for wide, high-movement construction and expansion joints in precast panels, concrete, masonry and cladding. Its +100%/−50% movement capability and suitability for specified joints up to 80mm make it the more demanding-joint option alongside P390. This 600ml sausage is ideal for longer joint runs.

Joint movement and elasticity

This polyurethane sealant is formulated to absorb cyclic expansion and compression movement of +100%/-50%. With an elongation at break exceeding 1,000%, it stretches to prevent adhesive or cohesive failure in high-movement joints, such as those found in aluminium composite materials, fiber cement sheet, and aluminium window installations. The moisture-curing formula prevents the formation of internal bubbles during the curing cycle, ensuring a dense, consistent seal even when applied to damp or moist substrates.

Numbers that matter

• +100% / -50% joint movement: Absorbs high-amplitude structural expansion and contraction in precast concrete, brickwork, and cladding systems.
• At least 1,000% elongation at break: Provides high elasticity to stretch across shifting joint gaps without tearing.
• 2.5-3mm per 24 hours cure rate: Sets progressively, requiring 7 days for full cure on porous substrates, and over 14 days in joints wider than 20mm.
• 90-minute skin time: Delivers a practical working window for tooling and finishing joint profiles.
• 2.8g/L VOC content: Low-emission formulation meeting Singapore Green Building Council standards.

Where to use it

Suitable for joints in:

• Insitu concrete and render
• Precast and tilt-up panels
• Aluminium composite materials and aluminium windows
• Brickwork and block work
• Metal cladding and stainless steel trays
• Plasterboard face and paper-lined recessed edges
• Fibre cement sheet
• Granite, sandstone, marble, and GRC panel systems

Limitations

• Do not use in chlorinated water such as swimming pools and spas.
• Do not use in constantly immersed salt water.
• Not suitable for PE, PP, PC, PMMA, PTFE, soft plastics, neoprene, or bituminous substrates.
• Do not use for glazing applications or in trafficable joints.
• Do not apply to cement-based substrates within 28 days of the initial pour or set.
• Do not apply in temperatures below 5°C or above 40°C.
• Avoid exposure to water or alcohol before the sealant has fully cured.
• Do not apply to joints less than 5mm in both width and depth, or joints larger than 80mm.
• White sealant may yellow on the surface under prolonged exposure to strong natural or artificial UV light.

Joint design and priming

To ensure correct sealant geometry and prevent three-sided adhesion, always install a backing rod before applying the sealant. The minimum allowable joint depth is 5mm, and the maximum joint width is 80mm. Tool the sealant to achieve a concave surface profile.

For joints 5mm to 10mm wide, maintain a 1:1 width-to-depth ratio. For joints wider than 10mm (up to 80mm), calculate the depth using the formula: Depth = (width in mm / 3) + 6.

The sealant adheres without primer to clean concrete, mortar, and bare aluminium. For optimum adhesion in high-stress joints or under extreme weather exposure, use the following priming procedures:

• Porous substrates: Use Bostik N49 Primer for maximum performance on porous surfaces, and always prime before periodically immersed or submerged applications. Dry, vertical expansion joints in concrete or masonry do not require priming if clean and uncontaminated.
• Non-porous substrates: Prime plastics and metallic substrates, including u-PVC, brass, copper, and stainless steel, with Bostik N40 Primer using the two-cloth method.
• Aluminium composite and cladding panels: These panels often carry protective wax or plastic coatings. Always test compatibility and conduct Pre-tested Adhesion to Substrate (P.A.T.S.) before application.

Paintability

Bostik Seal ‘N’ Flex One Plus P590 can be painted after curing for a minimum of 7 days. Solvent-containing coatings, such as enamels or oil-based paints, may react with the sealant surface and leave it tacky. Surface coatings may discolour when in direct contact with the cured sealant, or crack due to cyclic joint movement. Conduct a field test to verify coating compatibility.