Description
Dowsil 781 is a premium-quality acetoxy-cure silicone sealant designed for reliable sealing in sanitary, glazing, and general building applications. It provides excellent adhesion to a wide range of non-porous surfaces including glass, aluminium, ceramics, and enamel — making it ideal for sealing baths, sinks, showers, and internal glazing joints. Its built-in fungicide formulation resists mould and mildew, ensuring long-lasting hygiene and a clean appearance in wet or humid environments.
With a fast skin-over time and durable elasticity, Dowsil 781 delivers a watertight, professional finish that remains flexible even after years of service. Suitable for both professional installers and DIY users, it combines proven Dow technology with ease of use to create high-quality, dependable seals for kitchens, bathrooms, and general indoor applications.
Benefits
- Acetoxy-cure silicone providing fast skin formation and high strength
- Excellent adhesion to glass, ceramics, enamel, and non-porous substrates
- Ideal for sanitary, glazing, and general sealing in kitchens and bathrooms
- Contains fungicide for mould and mildew resistance in humid environments
- Cures quickly to a durable, flexible, and long-lasting joint
How to Apply
1. Surface Preparation
- Non-porous surfaces (e.g. glass, enamel, ceramics): Clean thoroughly with Dowsil R-40 Universal Cleaner or an equivalent solvent on a lint-free cloth; wipe dry immediately.
- Porous surfaces (e.g. concrete, brick): Mechanically clean using a stiff brush or abrasion to remove dust and debris. Ensure surfaces are completely dry before application.
2. Masking - Apply masking tape along both sides of the joint to ensure neat edges and prevent excess spread.
3. Application - Cut the nozzle to the desired bead width. Apply a continuous, even bead of Dowsil 781 using a standard sealant gun. Maintain steady pressure for consistent flow.
4. Tooling - Tool immediately after application to smooth and compact the sealant, achieving full contact with both joint sides. Remove masking tape before the sealant skins.
5. Curing
- Skin-over time: ≈ 20 minutes
- Full cure: 24 hours for 2–3 mm thickness (longer for deep joints)
Do not expose to water or cleaning agents during curing.
6. Joint Design Tips
- Maintain a 2:1 width-to-depth ratio for most joints.
- Minimum joint width: 6 mm.
- Avoid three-sided adhesion using a backer rod or bond-breaker tape where needed.
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