Achieving a lasting, clean seal in wet areas, especially around modern fixtures and tiles, demands a sealant that performs without compromise. Bostik 6S delivers precisely that: a neutral cure sanitary silicone designed to resist mould and adhere reliably to powder-coated metals, ensuring a durable, pleasant-to-work-with finish.

Why this product exists

Many conventional silicones struggle with mould growth in humid environments, emit strong odours during application, or fail to adhere consistently to contemporary finishes like powder-coated metals. Bostik 6S was formulated to prevent these common site regrets. It incorporates an effective fungicide to actively reduce mould and mildew, ensuring the seal remains hygienic and aesthetically pleasing. Its neutral curing system means a significantly more pleasant working environment, especially in confined spaces. Crucially, it offers excellent adhesion to powder-coated metal, making it a reliable choice for modern bathroom and kitchen fit-outs, all while maintaining a thixotropic, non-slump consistency for easy application in typical construction joints.

The numbers that matter

A sealant's performance hinges on its capacity to handle movement and maintain integrity over time. Bostik 6S delivers a dynamic movement capacity of ±25%. This means it can accommodate typical joint expansion and contraction in tiled wet areas, preventing the cracking and premature failure often seen with less flexible sealants. With a Shore A hardness of 17-22, it strikes a balance between flexibility and durability, ensuring the seal is robust enough for traffic but elastic enough to absorb minor impacts without compromise.

Its service temperature range of -50°C to 150°C highlights its resilience across diverse conditions, making it suitable for both general wet areas and the demanding thermal fluctuations of cool rooms, though the higher temperature end is for transient exposure. This wide operating range ensures the sealant maintains its properties without degrading prematurely.

What it's like to use

Applying Bostik 6S is straightforward. The neutral cure minimises strong odours, making it particularly suitable for interior work or smaller, more enclosed areas. It achieves a skin time of 8-10 minutes and a tooling time of 10 minutes, providing a practical window for working the bead to a smooth finish before it sets. Apply the sealant at ambient temperatures between -10°C and 40°C.

Proper surface preparation is crucial for optimal adhesion. Ensure substrates are dry, clean, and free from contaminants like oil or grease. For impervious surfaces, use a two-wipe cleaning process with a suitable solvent such as Z Bond R-40 or IPA. After application, tool the sealant immediately to ensure good wetting to the substrate and achieve a professional finish. Bostik 6S cures by absorbing atmospheric moisture, reaching a depth of 7mm in approximately 7 days. For cleanup of uncured sealant, use a clean cloth; do not use Isopropyl Alcohol around uncured sealant. Cured silicone requires mechanical removal.

Where this product excels

  • Bathrooms and shower screens: Ideal for sealing joints around ceramic tiles, fibreglass spa units, and shower screen frames where resistance to mould and mildew is paramount for hygiene and appearance.
  • Kitchen benchtops and splashbacks: Provides a durable, hygienic seal along the edges of benchtops and splashbacks, particularly where strong adhesion to powder-coated metal fixtures is required.
  • Cool rooms: The broad service temperature range and neutral cure make it an effective choice for sealing joints in cool room environments, maintaining a flexible seal despite temperature extremes.

How it fits in a real system

In sealing applications, proper joint design and preparation are critical to preventing premature failure. Bostik 6S is designed for flexible joints where three-sided adhesion must be avoided to allow for full movement. A closed-cell polyethylene backer rod, 25% larger than the joint width, should be used to control sealant depth and ensure two-sided adhesion. Typical joint depth is half the width, with a minimum of 6mm depth and width. Compatibility testing is always recommended for contact with plasticised sealants or certain backing rods that may cause discolouration or degradation.

Choose this when

  • Mould and mildew resistance is essential: When sealing wet areas like bathrooms, laundries, or commercial kitchens where hygiene and appearance are critical.
  • Working in confined spaces: The neutral cure system significantly reduces odours, making application more comfortable for installers.
  • Adhesion to powder-coated metal is required: For modern fixtures, window frames, or shower screens with powder-coated finishes.
  • A flexible, durable seal is needed: To accommodate joint movement in general construction and tiled applications.

Don't use this when

  • Not for: Structural glazing or adhering mirrors; use a dedicated structural glazing sealant like Bostik V60 Architectural Grade Silicone instead.
  • Not for: Applications requiring a paintable finish, as silicones generally do not accept paint.
  • Not for: Continuous underwater immersion or aquariums without specific confirmation from Bostik.
  • Not for: All stone types without prior stain testing, especially porous materials like granite or marble; consult the Bostik 5CLM data sheet for alternatives.
  • Not for: Totally confined spaces without atmospheric humidity, as the sealant requires moisture to cure.
  • Not for: Horizontal walkways or below-grade applications where specific engineering for high wear or hydrostatic pressure is required.

Bostik 6S meets the standard of NZFSA – C82. This classification indicates its suitability for use in areas where incidental food contact may occur, such as cool rooms, making it a reliable choice for commercial and industrial applications demanding specific hygienic standards.