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PU 25 FC: Fast-Curing Polyurethane Construction Sealant
PU 25 FC is a single-component moisture-curing polyurethane sealant engineered for high-performance construction joints. It combines flexibility, strength, and rapid cure time, making it suitable for both interior and exterior applications. PU 25 FC bonds tenaciously to porous and non-porous substrates including concrete, aluminium, fibreglass, timber, and painted surfaces. With excellent movement capability and resistance to UV, water immersion, and mechanical vibration, PU 25 FC is ideal for demanding environments such as facades, floor joints, expansion gaps, and precast concrete systems.
Key Features & Specifications
- High elasticity with ±25% movement capability
- Single-component – ready to use with no mixing
- Fast skin time and full cure for reduced downtime
- Excellent adhesion to a wide range of construction materials
- Resistant to water immersion, UV, vibration, and weathering
- Suitable for potable water and non-toxic once cured
- Can be painted with most water-based paints
Why Choose PU 25 FC?
- Trusted by professionals in commercial and civil construction
- Ideal for vertical and horizontal joints in concrete and precast
- Tough and flexible – handles expansion, contraction, and movement
- Performs under vibration and in exposed weather conditions
Best Practices: Do's & Don'ts
Do
- Apply to clean, dry, and properly primed surfaces if required
- Use in both vertical and horizontal joints
- Tool the joint before skin formation for smooth finish
- Store in a cool, dry place below 25°C
Don't
- Don’t apply in standing water or on wet surfaces
- Don’t expose to continuous UV without paint if colour stability is critical
- Don’t use without backer rod or bond breaker tape in deep joints
Trade Use Cases: Applied in the Field
Precast Installer: Vertical Panel Joint Sealing
The Problem
Precast joints in a warehouse need a flexible, durable seal with rapid curing.
The Solution
PU 25 FC applied directly into joint with foam backer rod, delivering flexible watertight seal.
Best Practice
Prime the substrate if porous, tool before skin forms, allow 24 hours before painting.
Commercial Fitout: Expansion Joint at Window Junction
The Problem
Movement cracks appearing in window perimeter seals due to temperature fluctuation.
The Solution
Replaced rigid sealant with PU 25 FC, which flexes with movement and resists UV exposure.
Best Practice
Install bond breaker tape behind sealant and tool smooth finish for professional result.
Frequently Asked Questions
What substrates does PU 25 FC bond to?
PU 25 FC adheres to most common construction materials including concrete, timber, brick, aluminium, metal, painted surfaces, and fibreglass. Priming may be required for some porous substrates.
Can PU 25 FC be painted?
Yes, PU 25 FC can be painted after curing using water-based paints. A compatibility test is recommended before overcoating with solvent-based coatings.
Is PU 25 FC suitable for potable water applications?
Yes, PU 25 FC is certified as non-toxic and is safe for use in applications involving contact with potable water once fully cured.
How much movement can PU 25 FC handle?
PU 25 FC accommodates ±25% movement, making it suitable for expansion and contraction joints in dynamic structures.
Can PU 25 FC be used in submerged areas?
PU 25 FC offers excellent resistance to water immersion after curing, but it should not be applied while the surface is wet or submerged during curing.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Expansion joints in concrete and masonry | Accommodates ±25% movement with watertight seal | Concrete Contractors, Builders |
| Facade and precast panel joints | UV-stable and paintable for architectural finishes | Facade Installers, Precast Contractors |
| Roof and wall cladding junctions | Flexible and weather-resistant under thermal movement | Roofers, Cladding Installers |
| Joint sealing in water-exposed areas | Water immersion resistance once cured | Waterproofers, Civil Contractors |
| Floor-to-wall joints in industrial buildings | Fast curing and abrasion resistant under traffic | Fit-Out Teams, Commercial Builders |
| Sealing around window/door frames | Adheres to aluminium, timber, and painted surfaces | Glaziers, General Contractors |
How to Apply PU 25 FC: Step-by-Step
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1. Surface Preparation
Ensure all bonding surfaces are clean, dry, and free from dust, grease, oil, or loose material. Use appropriate primer if needed.
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2. Mask Edges (Optional)
Apply masking tape to protect adjacent surfaces and achieve clean joint lines.
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3. Insert Backing Rod or Bond Breaker
Use foam backing rod or bond breaker tape to ensure proper joint depth and avoid three-sided adhesion.
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4. Apply Sealant
Cut nozzle to suit joint width. Extrude PU 25 FC evenly using a caulking gun, filling the joint completely.
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5. Tool Smooth
Tool the joint immediately with a soapy solution or sealant spatula to compact and shape the sealant before it skins over.
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6. Clean Up
Remove masking tape and clean tools with solvent before the sealant cures. Cured sealant must be removed mechanically.
Limitations & Safety
Product Limitations
Not suitable for continuous immersion unless specified by the manufacturer.
Should not be applied to wet, frozen, or contaminated surfaces.
Avoid use on polyethylene, polypropylene, or Teflon® without surface treatment.
Safety & Handling Requirements
Personal Protective Equipment
Wear gloves and eye protection. Avoid skin and eye contact with uncured product.
Ventilation
Use in a well-ventilated area. Avoid inhaling vapours during application.
Storage & Disposal
Store in original packaging below 25°C. Protect from moisture. Dispose of contents according to local regulations.
Emergency First Aid
Eyes:
Rinse immediately with clean water for several minutes. Seek medical attention if irritation occurs.
Skin:
Wipe off uncured material and wash with soap and water. Remove contaminated clothing.
Inhalation:
Move to fresh air. Seek medical advice if breathing becomes difficult.
Ingestion:
Do not induce vomiting. Rinse mouth and seek immediate medical attention.
Refer to the SDS (Safety Data Sheet) for complete safety guidance.
PU 25 FC Substrate Compatibility & Surface Preparation
Concrete & Precast Panels
Surface Preparation
Clean, dry, and free from laitance, dust, curing agents, or release oils. Abrade if necessary.
Primer Recommended
Use PU primer to improve bond strength in high-movement or exposed joints.
Timber (Dressed or Treated)
Surface Preparation
Ensure surface is dry and dust-free. Light sanding may improve adhesion.
Primer Not Required
Direct application generally suitable on dry timber surfaces.
Aluminium & Powder-Coated Metal
Surface Preparation
Degrease thoroughly and abrade lightly. Wipe clean with solvent.
Use Primer 50A
Promotes bond to non-porous and coated surfaces.
Fibreglass & Plastics (Selected Types)
Surface Preparation
Clean with isopropyl alcohol. Light abrasion recommended for glossy surfaces.
Primer May Be Required
Perform compatibility test. Use Primer 50A if adhesion is uncertain.
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