Description
Dowsil 799 is a low-modulus, neutral-cure silicone sealant designed for professional glazing and façade applications.
Its non-corrosive formulation ensures excellent adhesion to glass, aluminium, PVC-U, and coated metal surfaces without primer, making it ideal for window perimeter sealing, curtain walling, and metal cladding joints.
Once cured, it forms a permanently flexible, watertight seal that maintains elasticity under movement and temperature changes.
Engineered for both indoor and outdoor use, Dowsil 799 provides long-term resistance to UV, ozone, and extreme weather conditions, ensuring durable performance and clean, professional results.
Whether used on residential windows or large-scale architectural façades, it combines outstanding adhesion with a neutral finish that complements a wide range of substrates and building materials.
Benefits
- Neutral-cure, low-modulus silicone for glass, metal, and façade joints
- Excellent adhesion to glass, aluminium, PVC-U, and coated metals
- Resistant to UV, weathering, and temperature extremes
- Flexible and non-corrosive — suitable for sensitive metals and coatings
- Ideal for window perimeters, glazing, curtain walling, and metal cladding
How to Apply
1. Surface Preparation
- Non-porous surfaces (glass, aluminium, PVC-U): Clean with Dowsil R-40 Universal Cleaner or a suitable solvent on a lint-free cloth; wipe dry immediately.
- Porous materials (masonry, stone): Mechanically clean to remove dust, dirt, and loose particles.
Ensure surfaces are completely clean, dry, and free from oil or old sealant.
2. Masking - Apply masking tape along both sides of the joint for neat edges and to prevent overspreading.
3. Application - Cut the nozzle to suit the joint width and apply a continuous, even bead of Dowsil 799 using a standard or pneumatic gun. Maintain steady pressure and ensure full contact with both joint faces.
4. Tooling - Tool immediately after gunning using a spatula or tooling stick to compact the sealant and achieve a smooth finish. Remove masking tape before the surface skins.
5. Curing
- Skin-over time: ≈ 20–30 minutes
- Full cure: 24–48 hours depending on joint depth, temperature, and humidity
Protect from water and physical stress during the curing period.
6. Joint Design Tips
- Maintain a 2 : 1 width-to-depth ratio.
- Minimum joint width: 6 mm.
- Use a backer rod or bond-breaker tape to prevent three-sided adhesion.
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