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For high-strength structural bonding in marine and exterior construction, Unobond Polyurethane Adhesive provides a D4 water-resistant bond that withstands a 72-hour boiling water test. This single-pack, solvent-free gel adhesive cures via moisture to secure close-fitting joints across both porous and non-porous surfaces.
Unobond Polyurethane Adhesive reacts with moisture in the substrate or atmosphere to form a structural bond. During the curing process, the gel foams and expands slightly. This expansion forces the adhesive into gaps and surface irregularities, maximising the overall contact area. Because it cures to a cream or brown finish, it remains invisible in tight-fitting bond lines. The cured adhesive is resilient, paintable with acrylic, oil, or rubber-based paints, and can be sanded or cut without clogging tools or blunting blades.
Unobond Polyurethane Adhesive adheres common construction materials to themselves or to one another, provided at least one of the mating surfaces contains moisture. Suitable applications include:
All surfaces must be structurally sound, clean, and free of oil, grease, curing compounds, or release agents. Concrete must cure for a minimum of 28 days prior to application. Metal surfaces should be lightly sanded and wiped clean using a solvent such as xylene.
Apply the adhesive 10mm inward from the outer edge to prevent excessive squeeze-out. In dry, cool conditions or when bonding non-porous materials, lightly mist the mating surface with water to assist the curing process. Bring both surfaces together immediately and clamp tightly. Clamps must remain in place for at least 60 minutes at 23°C and 50% relative humidity, applying 50 PSI for softwoods and 150 PSI for hardwoods. Allow any squeeze-out to cure completely before removing it with a sharp blade; attempting to wipe wet squeeze-out will spread the adhesive and stain the surface.
Yes, Unobond is extensively used in wooden boat building due to its structural D4 water resistance. It withstands a 72-hour boiling water test, providing a durable, waterproof bond suitable for marine environments.
No, Unobond is an adhesive, not a gap filler. Using it to fill gaps will reduce the final bond strength. For filling cracks or gaps, Adheseal recommends its GapFilla product.
Unobond has a 10-minute skin time and achieves full cure in 24 hours at 23°C and 50% relative humidity. It requires moisture from at least one substrate to activate curing; dry, cool conditions or non-porous surfaces may benefit from a mist of water.
| Application | Key benefit | Primary trades |
|---|---|---|
| Wooden boat building | Structural D4 water-resistant bond withstands 72-hour boiling water test. | Boat builders, marine carpenters |
| Exterior woodwork assembly | Resilient, D4 rated bond performs in external conditions and is paintable. | Builders, landscapers, carpenters |
| Furniture and cabinet manufacturing | Strong, fast-setting bonds for interior and exterior joinery. | Cabinet makers, joiners |
| Floor mouldings and skirting boards | Excellent adhesion to wood and concrete, expands slightly to fill minor irregularities. | Carpenters, floor layers |
| General construction bonding (metal to wood/concrete) | Versatile adhesion across diverse materials including galvanised steel without corrosion, structural strength (5N/mm2 tensile). | General builders, steel fixers |
Correct surface preparation is critical to achieving structural bond strength and long-term performance.
Ensure surfaces are structurally sound, dry on the surface and free from dust, loose material, oils, curing compounds, and contaminants. Allow new concrete to cure for at least 28 days. Lightly sand timber where necessary, then remove dust before bonding.
Lightly abrade metals and dense surfaces to create a key. Use the two-wipe method with a suitable solvent such as xylene and clean cloths to remove oils and release agents, changing cloths regularly to avoid smearing contamination.
Prepare the cartridge correctly to maintain a consistent bead and control glue-line thickness.
Cut the cartridge tip, fit the nozzle, then trim the nozzle at a 45° angle to the required bead size. Insert into a suitable cartridge gun and ensure even trigger pressure for a steady flow.
Hold the gun at approximately 45° with the nozzle in contact with the surface. Apply Unobond around 10 mm in from the edge to minimise squeeze-out, then spread with a spatula to achieve a glue line of roughly 0.1–0.25 mm.
Bringing the joint together under even pressure is key to achieving structural performance.
Bring the mating surfaces together immediately after application. Use clamps, screws or nails to close joints and generate pressure across the bond line. Aim for some visible squeeze-out as an indicator of full contact.
Maintain pressure for at least 60 minutes at 23°C and 50% RH with a pressing load of around 0.6 N/mm². Full cure is typically achieved after approximately 24 hours under standard conditions.
Good cleanup and storage practice extends product life and keeps future work clean and efficient.
Clean tools and spills with xylene while the adhesive is still wet. Once cured, Unobond can only be removed by mechanical means such as scraping or sanding.
Use suitable hand wipes for skin cleaning. After use, seal the cartridge nozzle to limit contact with air and store in a cool, dry place between 15°C and 25°C to maximise shelf life.
Signal Word: Warning
Wear overalls, gloves (Nitrile Rubber suggested for intermittent contact), safety glasses, and a respirator. If an inhalation risk exists, use an organic vapour/particulate respirator compliant with AS/NZS 1715 and AS/NZS 1716.
Use in well-ventilated areas. Ensure adequate ventilation to keep air concentrations below exposure standards.
Store in a cool, dry, well-ventilated place away from direct sunlight, foodstuffs, incompatible materials, and ignition sources. Keep containers closed and upright. Dispose of according to local regulations; do not allow product to reach groundwater or sewage systems.
Proper surface preparation and adequate moisture are critical for Unobond to achieve its specified structural bond strength and D4 water resistance.
Surface prep: Ensure surfaces are structurally sound, dry, and free from dust, oils, and loose material. At least one wood surface must have a moisture content of at least 8% for curing. All joints must be close-fitting.
Primer: Not required. Substrate moisture is essential for cure.
Surface prep: Concrete must cure for at least 28 days. All surfaces must be clean, dry, and free from contaminants, form release agents, or curing compounds. Ensure adequate moisture is present in the substrate.
Primer: Not required. Substrate moisture is essential for cure.
Surface prep: Lightly sand metal surfaces and wipe clean with Adheseal Xylene solvent. Surfaces must be clean and dry. Ensure the mating substrate has sufficient moisture content to facilitate curing.
Primer: Not required, but Xylene cleaning is specified for metal. Unobond is non-corrosive to galvanised and zinc-coated steel.
Surface prep: Surfaces must be clean, dry, and free from contamination. Compatibility testing is recommended for specific plastics. Ensure the mating substrate has sufficient moisture content.
Primer: Not required. Conduct preliminary tests for adhesion to specific plastic types.
| Property | Value |
|---|---|
| Product Type | Polyurethane Adhesive |
| Curing System | Moisture |
| Cure Time | 24 Hours |
| Density (Specific Gravity) | 1.03 ±0.05 |
| Pressing Time | 1hr @ 0.6 N/mm² |
| Tensile Strength | 5N/mm2 |
| Tear Resistance | Up to 130kg/cm² |
| Application Temperature | +5°C to +35°C |
| Service Temperature | -30ºC to +100ºC |
| Working Time | 15m @ 23ºC & 50% RH |
| Skinning Time | 10m @ 23ºC & 50% RH |
| Volatile by Volume | <1% |
| Shelf Life | 12 months in original packaging |
| Storage | Cool and Dry between 15ºC and 25ºC |
| Resistance | Insensitive to Frost, Sensitive to Humidity (cures product), uninflammable |
| D Classification | Classified D4 water-resistant bond |
| Colour | Uncured: Translucent. Cured: Cream/brown |
| Packaging | 300ml cartridge |
| VOC Content | 0 g/Litre |
Here are some common examples on where Adheseal Unobond Polyurethane Adhesive used by our customers.
