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Price Per Unit: $14.08
Price Per Box: $12.67
Use DOWSIL 791 Silicone Weatherproofing Sealant for: Sealing curtain walls, glazing joints, and expansion joints on commercial façades and building exteriors.
DOWSIL 791 Silicone Weatherproofing Sealant is a premium, one-part, neutral-cure RTV silicone sealant designed specifically for weather-sealing applications in commercial construction. Engineered for maximum flexibility, it handles joint movement up to ±50% and delivers long-term adhesion on both porous and non-porous surfaces like glass, aluminium, masonry, and steel. With exceptional weather resistance, including UV, rain, and temperature extremes, this sealant is ideal for use in Australian climates and building codes. Its non-sag, low-string formulation makes application easy and precise.
Key Features of DOWSIL 791 Silicone Weatherproofing Sealant
- ±50% movement capability for superior flexibility in dynamic joints
- Excellent unprimed adhesion to most substrates including aluminium, masonry, and coated glass
- Outstanding weather resistance – unaffected by UV, ozone, rain, or snow
- Non-sag, easy-to-gun formula for clean application and tooling
Technical Overview
- Chemical Properties: One-part, neutral-cure RTV silicone
- Application Temperature Range: 4°C to 40°C (39°F to 104°F)
- Service Temperature: -50°C to 150°C (-58°F to 302°F)
- Joint Movement Capability: ±50%
- VOC Content: 45 g/L
- Colour: Black
Trade Professional Information
- Required Tools: Standard or air-operated caulking guns, joint backing material, masking tape
- Trade-Specific Tips: Tool within 15 minutes for optimal bead shape and surface contact
- Common Issues and Solutions: Avoid applying on wet or frost-laden surfaces; ensure surfaces are clean and dry for best adhesion
Storage and Shelf Life
- Storage Requirements: Store below 30°C in original sealed container
- Shelf Life Information: 12 months from date of manufacture
- Temperature Considerations: Do not store in freezing or excessively hot conditions
Certifications
- ASTM C920 Type S, Grade NS, Class 50
- ISO 11600 F&G-25LM
- EN15651-1/2:2012 – European Standard
Frequently Asked Questions About DOWSIL 791 Silicone Weatherproofing Sealant
Q: How should DOWSIL 791 be applied for best results?
A: Clean and dry all joint surfaces thoroughly. Install suitable backing material and apply the sealant in a continuous motion using a caulking gun. Tool within 15 minutes before skin formation to ensure proper bonding and finish.
Q: How does this product perform in extreme weather conditions?
A: DOWSIL 791 performs exceptionally in both hot and cold Australian climates. It offers excellent UV resistance, withstands heavy rain, and maintains elasticity from -50°C to 150°C, making it ideal for external building joints.
Q: Is DOWSIL 791 compatible with porous and non-porous materials?
A: Yes, it adheres well to a wide variety of substrates including aluminium, coated glass, masonry, and galvanised steel without the need for primer in most cases. For porous surfaces, a test placement is recommended.
Q: What are common issues and how can they be avoided?
A: Ensure surfaces are clean, dry, and free from contaminants. Do not apply in confined joints or on wet/frosty surfaces. Use backing rods to control joint depth and avoid three-sided adhesion for optimal movement.
Q: Is it safe to use and dispose of DOWSIL 791?
A: Use personal protective equipment and ensure good ventilation during application. Dispose of containers and unused material according to local regulations. Refer to the SDS for full safety guidance.
Use DOWSIL 791 Silicone Weatherproofing Sealant for:
- Glazing joints in aluminium or steel-framed facades
- Expansion joints in masonry or concrete panels
- Perimeter sealing around windows, doors, and curtain walls
- Weatherproofing vertical or horizontal exterior joints
Why Use DOWSIL 791 Silicone Weatherproofing Sealant:
- Ensures long-term joint flexibility with ±50% movement capability
- Reduces maintenance with excellent weather and UV resistance
- Improves job efficiency with easy gunning and fast skin time
- Compatible with a wide range of construction substrates
How to apply DOWSIL 791 Silicone Weatherproofing Sealant:
- Clean all surfaces thoroughly to remove dust, oil, old sealant, or coatings.
- Install backer rod or joint filler to maintain optimal joint depth.
- Mask adjacent surfaces to ensure clean sealant lines.
- Apply sealant in a continuous bead using a caulking gun or pneumatic dispenser.
- Tool the bead within 15 minutes to ensure complete surface contact and aesthetic finish.
- Remove masking tape before skin forms on the sealant.
DOWSIL 791 Silicone Weatherproofing Sealant limitations:
- Not suitable for structural glazing applications
- Do not use below-grade or in submerged applications
- Incompatible with surfaces that bleed oils, plasticisers, or solvents
- Not intended for paint-over finishes – paint typically does not adhere
- Do not use in totally confined joints; requires moisture to cure
- Avoid application on frost-laden or excessively hot surfaces (>50°C)
Safety precautions when using DOWSIL 791 Silicone Weatherproofing Sealant:
- Personal Protective Equipment: Use gloves, safety glasses, and long sleeves
- Ventilation: Apply in well-ventilated areas to avoid inhaling fumes
- Handling: Do not eat, drink, or smoke when handling the product; wash hands thoroughly
- Refer to SDS for detailed hazard and first aid information
DOWSIL 791 Silicone Weatherproofing Sealant can be used on the following substrates:
- Coated Glass – excellent unprimed adhesion
- Galvanised Steel – weather-resistant sealing for joints
- Masonry and Concrete – may require primer; conduct adhesion test
- Aluminium – suitable for curtain walls and façade frames
- Brick and Stone – test for potential staining or use ASTM C1248 approval
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