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Bostik Seal ‘N’ Flex One Plus P590: A Technical Overview
P590 is a low-modulus, moisture-curing polyurethane sealant designed for construction and façade joints. It cures bubble-free to a tough, flexible seal capable of cyclic movement of +100%/−50%, delivering reliable performance on concrete, precast/tilt-up, masonry, ACM/ETICS, fibre-cement, metals and natural stone. A non-sag thixotropic paste with easy tooling, it offers >1000% elongation, Shore A >25, and tensile strength around 1.2 N/mm². Typical skin time is ~90 minutes (23 °C/50% RH) with cure ~3 mm/24h on porous substrates; full cure ~7 days (allow ~14 days for joints >20 mm). Operating range approx. −30 °C to 80 °C. Paintable after full cure; field test recommended for coating compatibility.
>1000%
Elongation at Break for extreme joint movement
Core Features & Specifications
- Low modulus PU with +100%/−50% movement for high-movement façades and expansion joints.
- Bubble-free, non-sag cure for clean, predictable finishes and minimal rework.
- >1000% elongation, Shore A >25, tensile ~1.2 N/mm² for durable flexibility.
- Skin ~90 min; cure ~3 mm/24h (23 °C/50% RH, porous substrates).
- Service temperature approx. −30 °C to 80 °C; application 5–40 °C.
- Paintable after ~7 days (check coating compatibility on site).
- Compliance: ASTM C920/C1248, EN 15651-1 F-EXT-INT-CC 25LM, EMICODE EC1, SNJF F25E.
- Packaging: 300 ml cartridges & 600 ml sausages; multiple colours including Grey, White, Black, Limestone, Sandstone, Off-White, Epping Grey.
The Bostik Seal ‘N’ Flex One Plus P590 Advantage
- Handles extreme building movement without cracking—reduces call-backs and warranty risk.
- Non-sag, easy tooling bead—faster, neater installs and consistent finishes across elevations.
- Broad substrate compatibility—fewer primers in typical vertical porous applications.
- UV-resistant, exterior-ready—reliable façade performance in harsh Australian conditions.
- Proven standards—specifiable confidence for engineers and builders.
Proactive Troubleshooting
Scenario: Applying over damp or contaminated joints
Potential Outcome: Poor adhesion, blistering or premature failure leading to costly remediation.
Best Practice: Clean and dry substrates thoroughly; remove laitance, dust, oils and old sealant. Verify moisture and re-prep as required before gunning.
Scenario: Incorrect joint geometry without backing rod
Potential Outcome: Three-sided adhesion, cohesive stress and cracking under movement.
Best Practice: Install backing rod and tool to a concave profile. Observe width:depth rules (min 5×5 mm; for >10 mm width, depth = width/3 + 6 mm).
Applications in Practice: Trade Scenarios
For Builders (On-site Applicator): Precast panel expansion joints
The Professional's Challenge
Absorbing large seasonal movement in vertical joints without sag, voids or edge-staining—and keeping program moving.
The Adheseal Solution
Gun P590 over clean, dry precast with backing rod installed. Target 10–20 mm widths with correct depth profile; tool to a smooth concave finish. Non-sag paste enables crisp façades and predictable cure.
Best Practice Note
Prime only where required (critical/high-stress or immersed zones). Conduct site adhesion tests before commencing full elevation.
For Facade Installers (Business Owner/Operator): ACM & cladding interfaces
The Professional's Challenge
Maintaining clean sightlines on ACM/metal cladding while ensuring long-term elasticity and paint compatibility.
The Adheseal Solution
Use P590 for perimeter joints; for metals/plastics, prime with Bostik N40 where specified. Easy tooling delivers neat beads; UV durability suits exposed façades.
Best Practice Note
If painting, allow ~7 days cure and patch-test coating. Avoid solvent-rich enamels that may soften or craze over moving joints.
For Specifiers/Engineers (Specifier): Masonry control joints
The Professional's Challenge
Specifying a compliant, low-VOC sealant with documented movement capability and durability for exterior control joints.
The Adheseal Solution
P590 meets ASTM C920 and EN 15651-1 25LM with EMICODE EC1. Specify joint design to the stated width/depth ratios and service temperatures for robust movement accommodation.
Best Practice Note
Nominate priming only for critical exposures (immersion, high stress, highly porous). Include on-site adhesion verification in the spec.
Frequently Asked Questions
Do I always need a primer with P590?
Not in most clean, dry vertical porous joints. For critical/high-stress or immersed applications on porous substrates, use Bostik N49 Primer. For non-porous metals/plastics, use Bostik N40 Primer. Always perform site adhesion tests before full application.
When can I paint over P590?
After ~7 days cure under standard conditions. Avoid solvent-rich enamels/oil-based coatings which may react with the sealant or craze on movement. Always test the intended coating system on a cured sample first.
What joint sizes are supported?
Minimum 5×5 mm. Maximum width up to 80 mm. For widths >10 mm, set depth to (width/3) + 6 mm and tool to a concave profile over backing rod to prevent three-sided adhesion.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Façade expansion joints (concrete, precast, ACM, ETICS) | Low modulus + high movement capability prevents cracking and de-bonding | Builders, Facade installers |
| Masonry control joints (brick/block/render) | Non-sag paste and easy tooling for neat, consistent joints | Builders, Remedial contractors |
| Perimeter sealing to aluminium windows & cladding interfaces | UV-durable, paintable after cure; broad substrate compatibility | Builders, Glaziers, Cladding installers |
| Stone & GRC joints | High elongation accommodates thermal movement; clean edge finish | Stone/Facade contractors |
Applying Bostik Seal ‘N’ Flex One Plus P590: Enhanced Protocols & Best Practices
-
Surface Preparation
Ensure substrates are clean, dry, sound and free of laitance, dust, oils, curing agents and old sealant. Vacuum loose particles.
Cleaning
Use mechanical and solvent-free cleaning where practical. Wipe immediately; avoid residue.
Masking
Mask edges for neat lines; remove tape immediately after tooling.
Timing: Apply between 5–40 °C ambient/substrate temperatures.Pro Tip: Avoid damp surfaces; moisture under the bead risks blistering or adhesion loss. -
Joint Design & Backing
Install a closed-cell backing rod to control depth and prevent three-sided adhesion. Tool to a concave profile.
Geometry Rules
Min 5×5 mm; for widths >10 mm, depth = (width/3) + 6 mm; max width 80 mm.
Timing: Prime after backing rod installation where required.Pro Tip: Perform site adhesion pulls on representative areas before full elevation. -
Priming (Where Specified)
Use Bostik N49 for porous substrates in immersed/critical exposures. Use Bostik N40 on non-porous metals/plastics following the two-cloth method.
Pro Tip: Do not over-apply primer; thin, continuous films optimise adhesion without pooling. -
Gunning & Tooling
Dispense from 300 ml cartridge or 600 ml sausage using a suitable gun. Apply continuous pressure to fully wet the bond faces; tool to a smooth concave finish.
Nozzle Setup
Cut nozzle to bead size; maintain steady travel speed to avoid voids.
Timing: Skin forms ~90 min at 23 °C/50% RH. Avoid water/alcohol contact before full cure.Pro Tip: Remove masking immediately after tooling for crisp edges. -
Cure, Clean-up & Painting
Cure rate ~3 mm/24 h (porous). Full cure ~7 days; allow ~14 days for joints >20 mm. Clean uncured residue immediately; remove cured material mechanically. Paint only after full cure; patch test coatings.
Pro Tip: Use dedicated wipes for uncured clean-up; plan sequencing to minimise dirt pickup during skin formation.
Limitations & Safety
Product Limitations
Not for chlorinated water (pools/spas) or constant salt-water immersion.
Do not use on PE, PP, PC, PMMA, PTFE, soft plastics, neoprene, or bituminous substrates.
Not for glazing or trafficable joints.
Do not apply below 5 °C or above 40 °C. Avoid water/alcohol exposure before full cure.
Cement-based substrates must cure ≥28 days before application.
Joint size limits: min 5×5 mm; max width 80 mm.
White may surface-yellow under strong UV over time.
Safety & Handling Requirements
Personal Protective Equipment
Wear chemical-resistant gloves, safety glasses/goggles and protective clothing. Avoid skin and eye contact.
Ventilation Requirements
Use in well-ventilated areas. Manage vapours indoors and follow local site safety protocols.
Fire & Handling Precautions
Keep away from ignition sources during application and cure. Store cool, dry (5–25 °C), out of direct sun. Shelf life ~15 months unopened.
Emergency First Aid
Eyes:
Rinse cautiously with water for several minutes; remove contact lenses if present and easy to do. Seek medical advice.
Skin:
Wipe off uncured material and wash with soap and water. Do not use solvents on skin.
Inhaled:
Move to fresh air and rest. Seek medical attention if symptoms persist.
Swallowed:
Rinse mouth. Do not induce vomiting. Seek medical attention immediately.
Seek medical attention immediately in all cases of serious exposure.
Bostik Seal ‘N’ Flex One Plus P590 Application Guide
Concrete, Render, Brick & Block
Surface Preparation
Substrates must be sound, clean, dry and free of laitance, dust, curing agents, oils, old sealants and contaminants. Vacuum loose particles. Ensure substrate is cured (avoid cementitious substrates <28 days).
Primer Requirements
No primer typically required on clean, dry vertical porous joints. For immersed/critical exposures use primer.
Where maximum performance is required or periodic immersion is expected, prime with Bostik N49.
Bostik N49 PrimerMetals (Aluminium, Stainless, Copper, Brass)
Surface Preparation
Degrease and abrade if necessary. Ensure surfaces are dry and free of oxides. Use the two-cloth method where specified.
Primer Requirements
Primer recommended for non-porous metals.
Prime with Bostik N40 following the two-cloth method per primer TDS.
Bostik N40 PrimerPlastics (uPVC and Selected Plastics)
Surface Preparation
Clean thoroughly; ensure plasticisers or release agents are removed.
Primer Requirements
Primer recommended for non-porous plastics.
Prime with Bostik N40. Do not use on PE, PP, PC, PMMA or PTFE.
Bostik N40 PrimerNatural Stone (Granite, Sandstone, Marble)
Surface Preparation
Clean and dry; check for moisture migration and salts. Mask edges to protect ae
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