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N-40: A Technical Overview
Born from decades of on-site experience, Adheseal N-40 is the ultimate general-purpose silicone sealant, formulated to be the most versatile and reliable tube in any toolbox. Since 1989, it has been the trusted choice for Australian trades who need one product to do it all. Its neutral cure (oxime) chemistry ensures it won't corrode sensitive metals like Zincalume® or galvanised steel, while its built-in anti-fungal properties make it ideal for sanitary applications. N-40 delivers a high-strength, permanently flexible, and UV-stable bond to an unparalleled range of substrates, making it the definitive solution for countless applications.
±25%
Joint Movement Capability. N-40 accommodates significant structural movement, thermal expansion, and vibration without cracking or losing adhesion, ensuring a durable, long-lasting seal in dynamic building joints.
Core Features & Specifications
- Universal Adhesion: Bonds tenaciously to Zincalume®, Colorbond®, galvanised steel, glass, aluminium, PVC, timber, tiles, and most common construction materials.
- Neutral Cure System: Non-corrosive chemistry is safe for metals and concrete, preventing rust and surface damage common with cheaper acetoxy silicones.
- Extreme Temperature Resistance: Maintains permanent flexibility and performance in service temperatures from a frigid -50°C up to +150°C.
- Anti-Fungal & Sanitary: Contains a powerful fungicide to inhibit the growth of mould and mildew, making it ideal for bathrooms, kitchens, and laundries. Also certified safe for food preparation areas.
- Low VOC Compliance: With a VOC content of just 43g/L, N-40 meets Green Star environmental criteria, making it suitable for modern, sustainable building projects.
- Durable & UV Stable: Designed to withstand permanent UV exposure without cracking, yellowing, or breaking down, ensuring a long-lasting external seal.
The N-40 Advantage
- Simplify Your Inventory: Carry one tube that does the job of many. N-40's versatility means less searching for the right product and more time getting the job done.
- Work with Confidence: A proven performer for over 30 years, N-40 delivers a reliable seal you can trust, reducing the risk of costly and reputation-damaging call-backs.
- Protect Your Work: The non-corrosive formula protects your client's assets, from metal roofs to concrete panels, ensuring the sealant doesn't become the source of a future problem.
- Seal Any Environment: From hot, humid bathrooms to freezer rooms and sun-beaten roofs, N-40's robust formulation handles it all with ease.
- Achieve a Cleaner Finish: Low odour and easy tooling allow for a professional result every time, whether you're a plumber, builder, or shopfitter.
Best Practices: Do's & Don'ts
Do
- Ensure all surfaces are structurally sound, completely dry, and clean of all dust, oil, and loose material.
- Use the two-wipe process with a clean solvent like White Spirits for preparing non-porous surfaces.
- Design joints with a 2:1 width-to-depth ratio where possible for optimal flexibility and performance.
- Use a backing rod for any joint deeper than 10mm to control sealant depth and ensure a two-sided bond.
- Tool off the sealant within 5-10 minutes of application using a moistened spatula for a smooth, professional finish.
Don't
- Do not apply in totally confined spaces; the sealant requires atmospheric moisture to cure properly.
- Do not use on natural stone like marble or granite without performing a preliminary stain test.
- Do not use for continuous underwater applications such as swimming pools or in aquariums.
- Do not attempt to paint over the sealant, as paint will not adhere to the cured silicone surface.
- Avoid using on polycarbonate sheeting or for structural glazing applications, which require specialised products.
Applications in Practice: Trade Scenarios
For Plumbers & Roofers: Weatherproof Sealing
The On-Site Challenge
You need to seal roof flashings, gutters, and penetrations on a Colorbond® roof. The sealant must be UV stable, waterproof, flexible enough to handle thermal expansion, and critically, must not cause corrosion on the metal sheeting.
The System-Based Solution with N-40
N-40's neutral cure chemistry is non-corrosive, making it the perfect choice for Zincalume®, galvanised steel, and Colorbond®. Its ±25% joint movement capability handles the expansion and contraction of metal roofing sheets, while its excellent UV resistance prevents it from breaking down under the harsh Australian sun.
Best Practice Note
Ensure the metal surface is oil-free and dry. For a clean finish on visible flashings, mask both sides of the joint before applying the sealant and remove the tape immediately after tooling.
For Builders & Carpenters: General Construction Sealing
The On-Site Challenge
A typical day involves sealing around window frames, skirting boards, and expansion joints across multiple materials like aluminium, PVC, and treated timber. You need one reliable sealant that adheres to everything without needing multiple products.
The System-Based Solution with N-40
N-40 is the ultimate multi-tool. Its formulation provides excellent, unprimed adhesion to the vast majority of building materials. This versatility means you can confidently move from sealing an aluminium window to a PVC pipe penetration, and then to a timber expansion joint, all with the same tube.
Best Practice Note
For deep joints (over 10mm), insert a closed-cell backing rod to the correct depth. This not only saves sealant but ensures the joint has the ideal 2:1 width-to-depth ratio for maximum movement capability.
Performance Benchmark: N-40 vs. Standard Acetoxy Silicone
| Metric | N-40 (Neutral Cure) | Standard Acetoxy Cure | Advantage |
|---|---|---|---|
| Metal Corrosion | Non-corrosive Excellent | Corrosive to some metals | Safe to use on Zincalume®, Colorbond®, and galvanised steel without risk of causing rust. |
| Adhesion Range | Excellent on most surfaces Versatile | Limited, poor on concrete/metals | Provides reliable adhesion to a much broader range of building materials, including plastics and masonry. |
| Odour During Cure | Low Odour Good | Strong vinegar smell | More pleasant to work with, especially in enclosed or poorly ventilated interior spaces. |
| Joint Movement | ±25% High Flexibility | Typically ±20% or less | Superior flexibility accommodates more building movement, leading to a more durable, crack-free seal. |
Frequently Asked Questions
How long does Adheseal N-40 GP Silicone take to skin and cure?
Adheseal N-40 GP Silicone typically skins in about 10 minutes and cures at about 2 mm per day at 25°C and 50% humidity. Tool the bead within roughly 5 minutes for the cleanest line. Cure speed varies with atmospheric conditions and substrate porosity, so plan your handover accordingly for predictable performance.
Is Adheseal N-40 GP Silicone compliant for low-smoke or fire-tested projects?
Adheseal N-40 GP Silicone is fire tested to AS/NZS 1530.3 with a Smoke Developed Index of 0–1. That’s the sort of proof that helps on specified work and inspections. It’s a smart choice when you want documented performance rather than guessing and risking rework.
Can you use Adheseal N-40 GP Silicone in commercial kitchens and food preparation areas?
Adheseal N-40 GP Silicone is stated as safe to use in food preparation areas and is widely used in commercial kitchens and laundries. Prep properly (clean, dry, contamination-free) and tool it early for a sealed, sanitary joint. The payoff is a cleaner finish and fewer hygiene-related callbacks.
Do I need a primer before applying Adheseal N-40 GP Silicone?
Primer use for Adheseal N-40 GP Silicone is substrate-dependent, so an adhesion test is recommended on critical work. Where primer is needed, use Primer 50A for non-porous substrates and Primer 2001 for porous substrates. That small step removes doubt and helps prevent edge lift and delamination later.
Can Adheseal N-40 GP Silicone be used underwater or in swimming pools?
Adheseal N-40 GP Silicone is not suitable for underwater applications, including swimming pools. If the joint will be permanently submerged, follow the limitation and select a system designed for that exposure. Making the right call upfront is how you avoid no-win callbacks.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Shower wall-to-floor and wall-to-wall joints | Anti-fungal, flexible seal helps resist mould and joint cracking in humid wet areas | Plumbers, builders, tilers |
| Commercial kitchens and laundries | Low odour, sanitary sealing with low VOC for a cleaner, compliant finish | Builders, shopfitters, facility maintenance |
| External sealing on Colourbond/Zincalume/galvanised details | UV stable with -50°C to 150°C resistance for long-life weather exposure | Roofers, sheet metal workers, builders |
| General construction and shopfitting joints | Single-pack, ready-to-use workflow for fast sealing and reduced rework | Builders, carpenters, shopfitters |
| Marine and vehicle fabrication sealing (non-underwater joints) | Tough, flexible sealant that tolerates vibration and movement (±30%) | Fabricators, marine/boat builders |
| Sealing electrical installations and air conditioning penetrations | Maintains a waterproof flexible joint where movement and thermal cycling occur | Electricians, HVAC installers |
Applying Adheseal N-40 GP Silicone Sealant: Enhanced Protocols & Best Practices
-
1) Surface Preparation (Don’t skip it)
Surfaces must be structurally sound, stable, dry, and free of dust, loose material, oils/grease, release agents, curing compounds, and other contaminants.
Impervious substrates (tiles, glass, metal)
Use a two-wipe process with clean cloths. A suitable cleaner/solvent such as white spirits may be used; change cloths frequently to avoid spreading contamination.
Concrete and porous surfaces
Ensure concrete is cured for at least 28 days and fully dry. Remove dust/friable material so the sealant can key properly.
Timing: Plan prep so the joint is dry—sealing over dampness invites adhesion failures.Pro Tip: Mask joint edges before gunning for a neater finish and faster clean-up—less rework, cleaner handover. -
2) Priming (When the job can’t fail)
An adhesion test is recommended. Where primer is necessary, apply with a small brush and allow several minutes for solvent evaporation before sealing.
Non-porous substrates
Use Primer 50A where required after testing.
Porous substrates
Use Primer 2001 where required after testing.
Timing: Allow primer solvent to evaporate before applying sealant.Pro Tip: Priming only where needed protects margin—target it to critical joints and remove doubt where it counts. -
3) Joint Design & Backing (Let the joint move)
Aim for a 2:1 width-to-depth ratio where possible. Internal joints: minimum 5 mm width/depth; external joints: minimum 10 mm. Maximum joint width is 30 mm and depth 15 mm.
Backing rod for deeper joints
For joints greater than 10 mm deep, use a closed-cell polyethylene backing rod about 25% larger than the joint width to control depth.
Prevent 3-sided adhesion
On flat joints, use a polyethylene tape or release agent so the sealant bonds to two sides only—movement works as designed.
Timing: Set backing and masking before gunning—continuous workflow, cleaner finish.Pro Tip: Two-sided adhesion is how you get predictable performance from a ±30% movement sealant—skip it and you invite tearing. -
4) Install, Tool & Clean Up (Finish like a pro)
Apply between 5°C and 40°C (installation guide). Cut the nozzle at 45°, keep the tip in contact with both sides of the joint, and apply by pushing sealant ahead of the nozzle to force it firmly into place.
Tooling
Tool off with a moistened spatula before skin forms (tooling window ~5 minutes) for a smooth joint.
Clean-up
While wet, clean tools and spills with white spirit. Once cured, removal is by mechanical means.
Timing: Typical skin time is ~10 minutes; cure rate is ~2 mm/day at 25°C and 50% humidity.Pro Tip: Remove masking tape while the sealant is still wet—clean edges, faster tidy-up, and no costly callbacks over appearance.
Limitations & Safety
Product Limitations
Not suitable for totally confined spaces where atmospheric humidity can’t reach the sealant (it requires humidity to cure).
Not suitable for aquariums.
Not for adhering mirrors. High Power 609 can be used (test first).
Not for structural glazing. Use N-80 or N-60 Glazing silicone as specified for glazing applications.
Not recommended for composite panels. Adheseal recommends PU50FC (test first).
Not suitable for underwater applications, including swimming pools.
Some stone may stain—complete a stain testing program before use on stone.
Not for horizontal walkways or trafficable areas.
Not suitable for polycarbonate sheeting.
May discolour copper and brass. Avoid contact where aesthetics matter.
Do not treat with cleaning agents/solvents that may affect or discolour the sealant, particularly during curing.
This silicone is not paintable. Do not paint over silicone.
Safety & Handling Requirements
Personal Protective Equipment
PPE must be suitable for the task and hazards identified by your site risk assessment. Use appropriate eye and skin protection as required for sealing and solvent clean-up activities.
Ventilation Requirements
Ensure adequate ventilation, particularly when using solvents for surface prep or clean-up. Avoid working in totally confined spaces where curing humidity cannot reach the sealant.
Fire & Handling Precautions
Handle solvents used for prep/clean-up with care. Keep away from ignition sources and follow site handling procedures for flammable materials.
Emergency First Aid
Eyes:
Brush away loose particles. If irritation occurs, flush with lukewarm gentle flowing water for 5 minutes or until removed. Obtain medical advice if irritation becomes painful or persists.
Skin:
Brush away loose particles. If irritation occurs, flush with lukewarm gentle flowing water for 5 minutes or until removed.
Inhaled:
First aid is not generally required. If in doubt, contact a Poisons Information Centre or a doctor.
Swallowed:
Do not induce vomiting. Wash mouth with water and give some water to drink. If symptoms persist, contact a Poisons Information Centre or a doctor.
Seek medical attention immediately in all cases of serious exposure.
Poisons Information Centre: Australia 131 126, New Zealand 0800 764 766.
Adheseal N-40 GP Silicone Sealant Application Guide
Non-porous: Glass, Glazed Tiles, Porcelain, Enamel, Laminates
Surface Preparation
Use a two-wipe process and keep the surface dry, clean, and contamination-free. Remove oils/grease and change cloths frequently. A suitable cleaner/solvent such as white spirits may be used on impervious substrates.
Primer Requirements
Primer recommended where adhesion is critical (test first)
If a primer is required after testing, apply with a small brush and allow several minutes for solvent evaporation before sealing.
Primer 50A (for non-porous substrates)Metals: Colourbond, Zincalume, Galvanised Steel, Aluminium
Surface Preparation
Ensure surfaces are structurally sound and free of dust, loose material, oil, grease, and release agents. Keep substrates free from surface water and continual dampness to avoid adhesion issues.
Primer Requirements
Primer may be required on critical details (test first)
Run a quick compatibility/adhesion test before committing on unknown coatings or mixed materials.
Primer 50A (for non-porous substrates)Porous: Concrete, Masonry, Cementitious Surfaces
Surface Preparation
Concrete must cure for at least 28 days. Remove dust and friable material and ensure the substrate is dry—continual dampness can compromise adhesion and cause delamination.
Primer Requirements
Primer recommended for optimal adhesion (test first)
Where primer is needed, brush-apply and allow time for solvent to evaporate before applying sealant.
Primer 2001 (for porous substrates)Timber: Treated Wood and Common Building Timbers
Surface Preparation
Timber must be dry, stable, and clean. Remove dust and surface contaminants that can block adhesion, and avoid sealing onto wet timber where moisture can interfere with performance.
Primer Requirements
Primer may be required depending on timber treatment (test first)
Always test where contact with potentially incompatible treatments or materials occurs.
Primer 2001 (porous) or Primer 50A (non-porous areas) — select after testingDownload Adheseal N40 Documents
| Document | Type | Download |
|---|---|---|
| Adheseal N40 Technical Data Sheet | TDS | |
| Adheseal N40 Safety Data Sheet | SDS |
- Choosing a selection results in a full page refresh.