Dow Introduces New High-Performance Building Sealant Solution DOWSIL™ 791 Silicone Weatherproofing Sealant, Empowering G

Dow officially launched DOWSIL™ 791, a new generation one-part, neutral cure silicone weatherproofing sealant designed for the Chinese and global markets. The product is engineered to provide long-term, reliable waterproofing and air-tight sealing solutions for joint applications such as building facades, window and door installations, and prefabricated components. With its excellent weather durability, outstanding joint movement capability (±50%), and broad adhesion to various building materials including glass, anodized aluminum, and composites, it also meets stringent green building material certification requirements.

Against a backdrop of increasing extreme weather events due to climate change, the long-term sealing performance and durability of building envelopes have become paramount. DOWSIL™ 791 is designed for precisely these challenges. Its core strength lies in its ability to withstand extreme temperature cycles from -50°C to 150°C, curing to form a durable, flexible silicone rubber seal that resists hardening, cracking, or degradation from prolonged exposure to UV light, rain, snow, and ozone. This ensures building joints maintain integrity throughout the building's lifecycle, effectively preventing leaks and reducing maintenance costs.

DOWSIL™ 791 exhibits impressive physical and mechanical properties. Its cured durometer hardness (Shore A) of 25-30 provides good flexibility. A peel strength of 30 lb/in (5.4 kg/cm) and a tear strength (Die B) of 6.8 KN/m ensure the sealant possesses sufficient tear and cohesive strength when joints move. Crucially, its high joint movement capability of ±50% effectively absorbs and accommodates deformations caused by thermal expansion/contraction, wind load, and minor settlement of building structures, preventing seal failure due to stress concentration.

Beyond superior end-use performance, DOWSIL™ 791 is optimized for application convenience. The product is a ready-to-use, one-part formulation requiring no on-site mixing. Its non-sag property allows for perfect application in vertical and wide joints. An approximate 20-minute working time and 45-50 minute tack-free time provide ample window for application and tooling, facilitating a smooth, aesthetically pleasing seal. The product complies with international standards such as ASTM C920 Type S, Grade NS, Class 50, and meets Chinese National Standard GB/T14683-2017 as well as green building material product certification requirements (CNCA-CGP-13:2020 Three Stars), providing a reliable basis for material selection in green building projects.

• Building Façade Joint Sealing: For joints between unitized or stick curtain wall panels, and expansion joints between the curtain wall and building structure, providing long-term waterproofing and air tightness.
• Window/Door Installation and Perimeter Sealing: Creating an elastic seal between window/door frames and wall openings, improving the water and air tightness of the building envelope for enhanced energy efficiency.
• Metal Roofing and Skylight Joints: Suitable for sealing overlaps in metal sheets and connections between glazing panels and support structures, enduring long-term outdoor exposure.
• Precast Concrete (PC) Component Joints: For sealing horizontal and vertical joints between precast wall panels and floor slabs in prefabricated construction, accommodating minor movement between components.
• Other Industrial and Civil Building Joints: Waterproof sealing for joints in materials like stone, aluminum composite panels, etc.

To ensure optimal sealing performance, Dow provides detailed joint design guidelines and usage instructions in the Technical Data Sheet. A minimum joint width and depth of 6mm is recommended, and the use of a backer rod (e.g., closed-cell polyethylene foam) to control sealant depth and prevent three-sided adhesion is emphasized. Substrate surfaces must be clean, dry, and free of contaminants before application. For specific substrates, consulting Dow's adhesion test report is advised to determine if a dedicated primer is needed.

The product has a shelf life of 12 months when stored unopened below 32°C. Dow offers comprehensive product stewardship and technical support services to assist customers in proper product selection and application.