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For expansion joints, perimeter window fixing, and cladding joints where high movement capability is required, Adheseal Hi-Flex Construction Plus MS Polymer Sealant provides a neutral-cure, low-modulus elastomeric seal that accommodates up to 50% joint movement. Based on hybrid MS polymer technology, this single-component sealant complies with ASTM C920-CLASS 50 and ASTM C1248, maintaining permanent flexibility without bleeding or staining adjacent substrates.
Hi-Flex Construction Plus MS Polymer Sealant cures by reacting with atmospheric humidity to form a durable, elastic joint. Because it contains no isocyanates, solvents, or acids, it is non-corrosive to sensitive metals like galvanized steel, zinc-coated steel, and concrete. It is formulated to inhibit mould and biological growth, making it suitable for hot and humid service environments. The cured sealant can be painted with acrylic, oil, and rubber-based paints, though non-flexible paints may crack under movement.
This sealant is compatible with most common building materials, including concrete, masonry, brick, timber, metals (excluding lead and copper), plastics, stone, porcelain, fibreglass, powder coat, and waterproof membranes. Suitable applications include:
All surfaces must be clean, dry, structurally sound, and free of oils, grease, curing compounds, or release agents. Concrete must cure for at least 28 days before application. For non-porous substrates like aluminium, stainless steel, PVC, galvanized steel, and glazed tiles, clean and pre-treat with Adheseal 50A surface prep, then apply sealant between 30 minutes and 2 hours after priming. For porous substrates like concrete and brick, prime with Everflex Supaprime and apply sealant within the same 30-minute to 2-hour window.
Design joints to a 2:1 width-to-depth ratio. Internal joints must be a minimum of 5mm wide and 5mm deep; external joints must be a minimum of 12mm wide. For joints deeper than 10mm, use an open-cell foam backer rod (such as Adhefoam) sized 25% larger than the joint width to control depth and prevent three-sided adhesion.
Apply when temperatures are between 5°C and 40°C. For adhesive bonding, apply a triangular bead by holding the nozzle flat at a 90-degree angle, then compress the surfaces together to a minimum thickness of 2mm. Tool wet sealant with a moistened spatula within 5 minutes, before the 10-minute skin time. Wet sealant and tools can be cleaned with Xylene; cured material must be removed mechanically.
No. Hi-Flex Construction + is not suitable for continuous water immersion or internal swimming pool zones, and exposure to high chlorine levels must be avoided entirely.
The sealant cures at a rate of 2mm to 3mm per 24 hours at 25°C and 50% relative humidity. Actual skinning begins within 10 to 15 minutes of application.
It achieves strong primeless adhesion on most surfaces. However, critical configurations like multi-story buildings, high-stress joints, or extreme weather exposure require matching porous or non-porous primers.
Yes, it is paintable with acrylic, oil, and rubber-based paints. Always run a preliminary test, as non-flexible paints may crack if the underlying joint moves significantly.
External joints must maintain a minimum width and depth of 12mm. Aim for a 2:1 width-to-depth ratio, and use a backing rod for depths exceeding 10mm.
Surfaces must be structurally sound, dry, clean, and free of dust, oils, grease, curing compounds, or moisture transmission before application.
Surface prep: Ensure concrete has cured for at least 28 days to prevent delamination. Remove all friable material, dust, and form release agents.
Primer: Optional. For critical, highly stressed, or multi-story external applications, prime the surface with Everflex Supaprime using a brush, then wait 30 to 120 minutes before sealing.
Surface prep: Slightly roughen the metallic surface using a fine abrasive pad. Perform a standard two-wipe clean process using a clean cloth moistened with Xylene.
Primer: Optional. For high-performance installations, pre-treat non-porous metal surfaces with Adheseal 50A surface prep. Allow 30 to 120 minutes of flash time prior to sealant application.
Surface prep: Verify chemical compatibility with a spot test. Clean thoroughly using clean, frequently changed cloths to prevent transferring surface contamination.
Primer: Optional. Pre-treatment with Adheseal 50A surface prep is recommended on non-porous coatings to ensure maximum long-term bond durability under extreme weather.
Surface prep: Wipe away surface contaminants completely. Due to wide structural variations in plastic compounds, an adhesion test must be executed before general site application.
Primer: Required. Apply Adheseal 50A surface prep to clean PVC profiles, ensuring a minimum drying window of 30 minutes and a maximum window of 2 hours before gunning paste.
| Property | Value |
|---|---|
| Material Type | Hybrid MS Polymer |
| Curing System | Neutral |
| Density | 1.48 ± 0.05 g/cm³ |
| Tensile Strength | 0.65 MPa |
| Elongation | ~1100% (ASTM D412) |
| Movement Capability | ±50% |
| Shore A Hardness | ~25 (ASTM D2240) |
| Modulus | 0.41 MPa |
| Pot Life | ≈25 minutes at 23°C and 50% RH |
| Skin Time | ≈10–15 minutes at 23°C to 25°C and 50% RH |
| Application Temperature | +5°C to +40°C |
| Service Temperature | -40°C to +100°C |
| UV Resistance | 500 h – Good (meets industrial standard) |
| Chemical Resistance | Excellent to water & detergents, Moderate to diluted acids/alkalis, Petrol & oil short periods |
| Coverage Rate | 6 mm × 6 mm: 16.7 m, 10 mm × 10 mm: 6.0 m, 12 mm × 12 mm: 4.2 m, 20 mm × 10 mm: 3.0 m, Triangular 10 mm × 10 mm: 12 m |
| Substrate Compatibility | Paintable (test first, non-flexible paints may crack) |
| VOC Content | 1.10% (USEPA) |
| Certifications & Standards | Class 50 |
| Shelf Life | 12 months (original packaging) |
| Storage Conditions | Cool, Dry, 10°C to 35°C |
| Specific Gravity | 1.45 +/- 0.05 (ASTM D1475) |
| Consistency | Non-Sagging Paste |
| Clean Up | Xylene / Adheseal Citrus Wipes (for skin) |
| Staining | Non-staining (ASTM C510 & ASTM C1248) |
Here are some common examples on where Adheseal Hi-Flex Construction Plus MS Polymer Sealant used by our customers.
