For expansion, control, and perimeter joints subject to high movement, N70 Industrial Silicone Sealant is a neutral-cure oxime silicone that accommodates up to ±50% joint movement. It cures to form a permanently flexible, dust-proof gasket that adheres to challenging substrates including glazed ceramic tiles, porcelain, vitreous enamel, and common building metals without corroding galvanised steel or zinc coatings.
What it does
N70 Industrial Silicone Sealant functions as a weather seal, general glazing sealant, and flexible joint gasket. The oxime (neutral) curing mechanism relies on atmospheric humidity to cure, meaning it will not react with or corrode metals like Zincalume, Colorbond, galvanised steel, stainless steel, or aluminium, nor will it attack concrete or masonry. Once fully cured, it achieves an elongation at break of 600% and an elastic recovery of over 90%, allowing joints to return to their original shape after extension or compression. It maintains its seal across a service temperature range of -50°C to 150°C, making it stable under direct UV exposure and outdoor weathering.
Numbers that matter
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±50% movement capability: High permanent flexibility to accommodate significant joint expansion and contraction without adhesive or cohesive failure.
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600% elongation at break (ISO 8339): Extreme stretch capacity before the cured sealant material ruptures.
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2mm per day cure rate: Curing speed at 25°C and 50% relative humidity; actual times will vary depending on temperature, humidity, and substrate porosity.
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25 to 30 Shore A hardness: Medium-soft durometer hardness that provides a balance of flexibility and tear resistance for joint sealing.
Where to use it
Suitable for internal and external applications across construction, HVAC, marine, and manufacturing sectors. Common applications include:
- Expansion and control joints in masonry, concrete, driveways, and walkways
- Perimeter sealing around windows, doors, and curtain walls
- General glazing and glass partitions
- Air-conditioning duct seals and HVAC penetrations
- Roof, gutter, skylight, and solar installations
- Wet areas, ceramic tiles, and around pools (above the waterline during application)
Limitations
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No confined spaces: Do not use in totally confined spaces; the sealant requires atmospheric humidity to cure.
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No underwater application: Do not apply sealant underwater (including swimming pools or ponds). Once fully cured, it is suitable for below-waterline applications, but project-specific confirmation is required.
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Not for structural glazing: Do not use for structural glazing; use N-80 or N-60 Glazing silicone instead.
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Not paintable: This silicone cannot be painted over. Do not paint.
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Substrate exclusions: Do not use on aquariums, polycarbonate sheeting, or for adhering mirrors (use High Power 609 instead).
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Composite panels: Do not use on composite panels without testing first; Adheseal recommends Hi Flex Construction for this application.
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Natural stone risk: May stain some natural stone. S100 is recommended for marble and granite after a stain testing program.
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Metal discolouration: Sealant may discolour copper and brass surfaces.
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Chemical sensitivity: Do not clean or treat the sealant with solvents, materials, or cleaning agents that may affect or discolour it, especially during the curing phase.
Joint design and dimensions
Where possible, design joints to a 2:1 width-to-depth ratio. Internal joints require a minimum width and depth of 5mm. External joints require a minimum width of 10mm. The maximum allowable joint width is 30mm, and the maximum depth is 15mm.
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5mm to 10mm joint width: Depth must equal width, minimum 5mm.
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10mm joint width: Depth must be 5mm to 8mm.
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15mm joint width: Depth must be 7mm to 10mm.
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20mm joint width: Depth must be 10mm.
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25mm joint width: Depth must be 12mm.
For joints deeper than 10mm, install a backing rod 25% larger than the joint width to control depth. The sealant must only bond to two sides to allow correct movement; use polyethylene release tape on flat joints to prevent three-sided adhesion.
How to apply
Apply when substrate and ambient temperatures are between 5°C and 40°C.
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Substrate preparation: Surfaces must be clean, dry, structurally sound, and free of dust, oil, grease, curing compounds, and surface water. Concrete must cure for a minimum of 28 days prior to application to avoid mould growth, poor adhesion, and delamination.
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Impervious surfaces: Clean non-porous substrates using the two-wipe process with clean cloths moistened with Acetone or 100% White Spirits.
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Priming: An adhesion test is recommended. If a primer is required, apply with a small brush and allow to dry for several minutes before sealing. Use 50A Primer for non-porous substrates and Everflex Supaprime for porous substrates.
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Application method: Cut the sausage opening and cut the nozzle at a 45° angle. Extrude the sealant by pushing it ahead of the nozzle to ensure intimate contact with both joint faces.
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Finishing: Tool the joint with a moistened spatula within 15 minutes, before the skin forms (approximate skin time is 20 minutes). If masking tape was used, remove it while the sealant is still wet.
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Clean up: Clean wet tools and excess sealant with white spirit or isopropyl alcohol (IPA). Cured sealant must be removed by mechanical means.