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For tiled wet areas, bathrooms, laundries, and kitchens where mould and mildew are constant risks, Bostik 6S Silicone Sealant provides a flexible, non-slumping seal. Formulated with an active fungicide, this neutral-cure silicone prevents fungal growth on joints around ceramic tiles, shower screens, kitchen benchtops, and splashback edges, while avoiding the harsh odours of acid-cure sealants in confined spaces.
Bostik 6S contains an additive that inhibits mould and mildew growth, keeping tile grout joints, shower surrounds, and bath edges clean. Because it is a neutral-curing system, it does not release highly corrosive acidic vapours, making it safer to use on sensitive substrates like powder-coated metal framing and fiberglass spa units. The thixotropic compound maintains a zero-slump profile (Nil sag to BS 5889) when applied in vertical construction joints or overhead corners. It cures by absorbing atmospheric moisture to form a durable, flexible seal that carries the NZFSA – C82 standard for use near food areas like splashbacks and countertops.
To avoid joint failure, design joints to prevent three-sided adhesion. Use a closed-cell polyethylene backing rod that is 25% larger than the joint width to control depth and prevent bottom-surface bonding. The minimum acceptable joint depth is 6mm; for weather seals, the depth must be half the joint width.
Ensure all substrates are dry and free from frost, oil, dirt, and grease before extrusion. For non-porous, impervious substrates, clean the surface using a clean, frequently changed cloth with a suitable cleaner like Z Bond R-40 or Isopropyl Alcohol (IPA) via the two-wipe process. Tool the sealant firmly into the joint before it skins over (within 8 to 10 minutes) to improve substrate contact and ensure a flush finish.
Yes, Bostik 6S is formulated for these applications. It contains an effective fungicide to reduce mould and mildew growth, which is critical in wet areas like bathrooms, shower screens, and ceramic tiled joints.
No, Bostik 6S is generally not recommended for all stone types. For granite, marble, and some porous stones, it is recommended to perform stain testing or consider Bostik 5CLM for specific applications to prevent potential discolouration.
Bostik 6S is a neutral cure silicone. This means it has a low odour compared to acetic cure silicones, making it more pleasant and safer to use, especially in poorly ventilated or confined work areas like bathrooms and cool rooms.
No, this sealant is not paintable. Do not attempt to paint over cured Bostik 6S, as paint will not adhere properly and may crack or peel.
| Application | Key benefit | Primary trades |
|---|---|---|
| Bathrooms and shower screens | Reduces mould and mildew growth with effective fungicide; provides a durable, flexible seal with ±25% movement capacity. | Plumbers, Tilers, Bathroom Renovators |
| Ceramic tile and grout areas | Maintains aesthetic appeal by resisting mould; neutral cure prevents damage to sensitive materials; long-lasting flexibility. | Tilers, Builders |
| Kitchen benchtops and splashbacks (edges) | Offers a hygienic, waterproof seal; excellent adhesion to powder-coated metal fixtures; neutral cure for interior use. | Joiners, Kitchen Installers, Tilers |
| Cool rooms | Maintains a secure, flexible seal across service temperatures from -50°C to 150°C; neutral cure minimises odour in enclosed spaces. | Cool Room Installers, Commercial Builders |
| Joints requiring dynamic movement | Accommodates joint expansion and contraction with ±25% movement capacity, preventing cracking and premature failure. | Builders, Tilers |
The Engineering Challenge: Achieving a permanently flexible, waterproof, and mould-resistant seal in high-movement corner joints between an acrylic shower base and tiled walls.
The System-Based Solution with Bostik 6S Sanitary & Tile Silicone Sealant: The sealant's ±25% movement capability easily handles the differential movement between the tiled wall and the shower base. Its integrated fungicide prevents mould growth in the constantly damp environment, and its excellent adhesion profile ensures a tenacious bond to both the ceramic tiles and the acrylic base for a fully waterproof system.
Best Practice Note: Install a closed-cell backing rod in the joint to ensure a depth of half the joint width (min 6mm). This prevents three-sided adhesion, allowing the sealant to flex correctly and maximising its service life.
The Engineering Challenge: Creating a long-lasting, weatherproof seal on powder-coated aluminium window frames, which are notoriously difficult for some sealants to adhere to and are subject to extreme UV and thermal cycling.
The System-Based Solution with Bostik 6S Sanitary & Tile Silicone Sealant: Bostik 6S is specifically noted for its excellent adhesion to powder-coated metal. Its neutral cure chemistry won't damage the finish, and its superior UV and weathering resistance ensures the seal won't break down, crack, or peel, even in the harshest Australian sun.
Best Practice Note: For a flawless bond, surface preparation is key. Use the two-wipe process with a recommended solvent cleaner (like Z Bond R-40) to remove all residues from the powder-coated surface before sealant application.
Signal Word: Danger
Suspected of causing cancer. May damage fertility or the unborn child. May cause damage to organs.
Wear safety glasses with side shields or goggles, suitable protective clothing, and suitable gloves. In conditions where high vapour concentrations are expected during the cure stage, use an organic gases and vapours filter conforming to EN 14387.
Ensure adequate ventilation during use, especially in confined spaces. Small amounts of methanol and 2-butanone, oxime are formed and released upon curing.
For emergency information, contact the Poisons Information Centre on 131 126 or the Emergency Response Service on 1800 033 111.
Store in a cool, dry place at no more than 25°C and below 50% relative humidity. Protect from moisture. Keep away from food, drink, and animal feeding stuffs. Prolonged storage at high temperatures may affect shelf life and ultimate performance. Shelf life is 12 months from the date of manufacture.
Dispose of contents/container to an approved waste disposal facility, in accordance with local authority regulations. Do not dispose of down drains or into local waterways.
Proper substrate preparation is essential for reliable long-term sealant performance and adhesion, preventing callbacks.
Surface prep: Surfaces must be dry and free from oil, dirt, and grease. Use the two-wipe process with clean cloths and a suitable cleaner/solvent such as Z Bond® R-40 or IPA.
Primer: Not required for typical adhesion to these substrates. If adhesion is questionable, consult Bostik for specific primer recommendations.
Surface prep: Ensure surfaces are clean, dry, and free from contaminants. Specific attention to dust and loose particles is needed.
Primer: Optional. A primer may be required for satisfactory adhesion, and stain testing is strongly recommended on all stone types before full application. For some porous stones, Bostik 5CLM may be a more suitable alternative sealant.
| Property | Value |
|---|---|
| Skin Time | 8-10 minutes |
| Tack Free Time | 30 minutes |
| Tooling Time | 10 minutes |
| Sag or Slump | Nil |
| Shore A Hardness | 17-22 |
| Modulus at 100% Elongation | 0.4 MPa |
| Tensile Strength | 1.1 to 1.5 MPa |
| Elongation at Rupture | 630-670% |
| Peel Strength after UV through Glass | 50 N/25mm |
| Dynamic Movement Capacity | ±25% |
| Accelerated Ageing and Weathering | Excellent |
| Application Temperature | -10°C to 40°C |
| Service Temperature | -50°C to 150°C |
| Relative Density | 1.01 |
| Dynamic Viscosity | 150000 - 250000 mPa s |
| Cure Depth | 7mm in 7 days |
| Shelf Life | 12 months |
Here are some common examples on where Bostik 6S Silicone Sealant used by our customers.
