Everflex PU240 Polyurethane Adhesive and Sealant

For joint sealing and structural bonding where vibration, mechanical wear, or water exposure cause standard sealants to fail, Everflex PU240 Polyurethane Adhesive and Sealant provides a high-strength, flexible joint. This high-modulus, moisture-curing polyurethane formulation is pick-resistant and accommodates joint movement up to ±25% in high-traffic pavement joints, metal cladding, and marine assemblies.

How it works

Everflex PU240 cures by reacting with atmospheric moisture to form a tough, elastomeric barrier. With a Shore A hardness of 35, it delivers high tear and abrasion resistance, making it suitable for high-exposure environments like car parks, driveways, and marine teak decks. Once fully cured, the compound is stable for continuous submersion in below-waterline marine applications. It can be sanded and painted with acrylic, oil, or rubber-based coatings once cured.

Numbers that matter

• ±25% movement capability: Accommodates expansion and contraction in dynamic joints without adhesive or cohesive failure.
• 4mm per 24 hours cure rate: Deep-section moisture cure (measured at 25°C and 50% relative humidity) with a 20-minute working time.
• 80% elongation at break: High elasticity under tension (tested to ISO 8339) to maintain seal integrity under mechanical load.
• -40°C to +90°C service temperature: Maintains structural bond strength and flexibility across extreme temperature cycles.
• 76 g/L VOC content: Low-odour, non-toxic formulation meeting California South Coast Air Quality Management District Rule 1168.

Where to use it

Everflex PU240 bonds to most common construction materials. Acceptable substrates include:

• Masonry and wet trades: Concrete, brick, stone, porcelain, aerated concrete, and cement-based renders.
• Metals: Aluminium, anodised aluminium, stainless steel, galvanised/zinc-coated steel, and powder coats.
• Timber and plastics: Timber, PVC, acrylic-painted surfaces, and fibreglass.
• Elastomers: Natural rubber and compatible waterproof membranes.

Limitations

• Do not use in totally confined spaces, as the product requires atmospheric humidity to cure.
• Not suitable for structural glazing; use N-80 or N-60 glazing silicone instead.
• Do not use for adhering mirrors; use Hi-Power/MS609.
• Not suitable for aquariums or internal swimming pools where chlorine levels exceed 5ppm.
• Do not use on bituminous surfaces, EPDM rubber, or substrates that leach oils, plasticisers, or solvents.
• Do not use on copper or brass without testing, as the sealant may cause discolouration.
• Do not use on marble or granite without stain testing; S100 is recommended for these stone types.
• White polyurethane may yellow slightly under prolonged UV exposure; exposure to UV may also cause the surface to develop a matte appearance or minor micro-cracking up to 0.5mm deep, which does not affect sealing performance.
• Do not apply during active substrate moisture-vapour transmission, as rising vapour can cause bubbles to trap in the curing sealant.
• Avoid exposing uncured sealant to cleaning agents, solvents, or alcohol.

Installation and joint design

Ensure all substrates are clean, dry, and free of grease, release agents, and curing compounds. Concrete must cure for a minimum of 28 days before application. For impervious substrates, clean the surface using Xylene and the two-wipe process.

Maintain a 2:1 width-to-depth ratio for sealant joints. Internal joints require a minimum width and depth of 5mm; external joints require a minimum width of 12mm. For joints deeper than 10mm, insert an open-cell backer rod (sized 25% larger than the joint width) to control depth and prevent three-sided adhesion.

Priming instructions:

• Non-porous surfaces (Aluminium, stainless steel, PVC, powder coats): Roughen the surface with a fine abrasive pad, clean, and apply Adheseal 50A surface prep. Allow between 30 minutes and 2 hours drying time before applying the sealant.
• Porous surfaces (Concrete, render, brick): Apply Everflex Supaprime with a brush. Allow between 30 minutes and 2 hours drying time before applying the sealant.

Application method:

• As a joint sealant: Apply at temperatures between 5°C and 40°C. Push the sealant ahead of a 45-degree angle nozzle to fill the joint completely and prevent air entrapment. Tool the surface within 5 minutes using a moistened spatula before a skin forms.
• As an adhesive: Cut a wedge in the nozzle to dispense a triangular bead. Join the components to compress the bead to no less than 2mm to ensure complete surface wet-out.