Bostik Seal ‘N’ Flex One Plus P590 Polyurethane Sealant 300ml

For expansion and construction joints in precast panels, concrete cladding, and window installations where joint movement causes standard sealants to shear or pull away, Seal ‘N’ Flex One Plus P590 Polyurethane Sealant 300ml provides a low-modulus, high-movement barrier. This polyurethane formulation cures bubble-free—even on damp or moist substrates—to handle extreme joint expansion and compression cycles without structural failure.

High-movement joint performance

Seal ‘N’ Flex One Plus P590 is a low-modulus sealant, meaning it remains highly flexible after curing. It accommodates joint expansion up to +100% and compression down to -50%, absorbing the thermal expansion and contraction common in precast concrete tilt-up panels, brickwork, metal cladding, and aluminium window frames. With an elongation at break exceeding 1000%, it stretches reliably over wide movement cycles without tearing or losing adhesion to the joint faces.

Numbers that matter

• +100% / -50% joint movement: Absorbs high cyclic movement in external cladding joints, reducing the risk of adhesive failure under extreme thermal shifts.
• > 1000% elongation at break: High elasticity prevents the sealant from tearing internally when joints open to their maximum width.
• 2.5-3mm per 24 hours cure rate: Standard moisture-curing window, reaching full cure in 7 days on porous substrates, and requiring more than 14 days for joints wider than 20mm.
• -30 to 80°C temperature resistance: Maintains its physical seal properties and elasticity in harsh external environments and high-exposure metal facades.
• 2.8g/L VOC: Low-emission formulation suitable for environmentally rated projects, conforming to Singapore Green Building Council standards.

Where to use it

This sealant bonds to major construction substrates and panel systems, including:

• Concrete and masonry: Insitu concrete, render, precast and tilt-up panels, brickwork, block work, GRC, and natural stone such as granite, sandstone, and marble.
• Cladding and windows: Aluminium composite materials, metal cladding, fibre cement sheet, and aluminium windows.
• Plasterboard: Plasterboard face and paper-lined recessed edges.
• Metals and plastics: Aluminium, u-PVC, brass, copper, and stainless steel.

Application and priming rules

Bostik Seal ‘N’ Flex One Plus P590 adheres to standard concrete, mortar, and bare aluminium without a primer. However, specific installation conditions require substrate priming to guarantee bond integrity:

• Porous substrates: Use Bostik N49 Primer for maximum performance on porous surfaces, and always prime for periodically immersed or submerged applications. Vertical joints in dry, clean concrete or masonry do not require priming.
• Non-porous substrates: Use Bostik N40 Primer for non-porous plastic and metal substrates, including u-PVC outlets, pipework, brass, copper fittings, and stainless steel trays or flashings. Apply using the two-cloth method.
• Composite panels: Coated aluminium panels often carry protective wax or plastic coatings; always perform a Pre-tested Adhesion to Substrate (P.A.T.S.) test to verify bonding before full application.
• Joint geometry: For joints 5mm to 10mm wide, use a 1:1 width-to-depth ratio. For joints wider than 10mm (up to 80mm), calculate depth using the formula: Depth = (Width / 3) + 6mm. Always install a backing rod before priming to control sealant depth and prevent three-sided adhesion.

Limitations

• Do not apply to cement-based substrates within 28 days of the initial pour or set.
• Do not use in trafficable joints, for glazing applications, or in chlorinated water environments like swimming pools and spas.
• Do not use in constantly immersed salt water.
• Do not apply in temperatures below 5°C or above 40°C, or expose the sealant to water or alcohol before it has completely cured.
• Do not use on PE, PP, PC, PMMA, PTFE, soft plastics, neoprene, or bituminous substrates.
• Do not use in joints less than 5mm or wider than 80mm.
• White sealant may yellow on the surface if exposed to strong natural or artificial UV light for prolonged periods.
• If painting, wait a minimum of 7 days. Solvent-based coatings (such as enamels or oil-based paints) may react with the sealant, leaving a tacky surface. Surface coatings may crack, craze, or discolour due to joint movement.