Protecting Architectural Aesthetics & Durability: The Launch of DOWSIL™ 791/991 High Performance Silicone Weatherproofin

DOWSIL™ 791 (referencing the attached TDS, with 991 as a similar high-tier variant) is a one-part, neutral-curing, high-performance silicone weatherproofing sealant. It is specifically designed for long-term elastic waterproof sealing in general building curtain walls and assembly applications. Beyond excellent weathering resistance against sunlight, rain, snow, ozone, and extreme temperatures (-50°C to 150°C), its formulation focuses on providing stable adhesion and a reasonable working time (approx. 20 mins working time, 45-50 mins tack-free) to ensure smooth, neat joint finishes.

DOWSIL™ 791 cures to exhibit outstanding physical properties: Shore A Hardness of 25~30, ultimate elongation up to 420%, joint movement capability of ±50%, and tensile strength (at 100% elongation) of 0.40 MPa. This medium-low modulus characteristic allows the sealant to effectively release stress during thermal expansion or dynamic building movements, preventing cohesive failure. It complies with stringent domestic and international standards such as GB/T 14683-2017, ASTM C920, and EN 15651, also holding China Green Building Material (3-star) certification, balancing performance with sustainability.

Leveraging its non-slump property (0 mm sag, per TDS) and good adhesion to glass, aluminum, and composite panels, this series is widely used in:

• Stone Curtain Walls & Anti-Stain Sealing (Extension based on 991 traits): In high-end commercial or public buildings using natural stone (marble, granite), anti-stain formulations (like 991) prevent sealant migration (oil bleeding) and peripheral staining, keeping facades clean while accommodating ±50% movement to match differing expansion rates of stone vs. frames.
• High-rise Glass & Metal Panel Weathersealing: Ideal for perimeter sealing of vision/structural glazing and joints in metal composites (e.g., fluorocarbon-coated aluminum) in offices or airports. Its weathering stability ensures the bead remains elastic without cracking under long-term UV and acidic rain, maintaining waterproof integrity.
• Expansion Joints & General Assembly: Used in large public venues (stadiums, exhibition centers) for concrete expansion joints or window frame sealing. The practical ~20-minute working time allows sufficient tooling for a neat finish.

standard protocols ensure longevity: substrates must be cleaned via the "two-rag method" with appropriate solvents (e.g., MEK, alcohol; avoid soapy water which leaves residue); joint design must avoid "three-sided bonding" using closed-cell polyethylene backup rod to control depth (min width/depth ≥6mm); tooling should be completed before skinning (within working time). For critical structural glazing, refer to DOWSIL™ 995 standards, whereas the 791/991 series focuses primarily on weatherproofing functions.

Whether for system sealing in new landmark curtain walls or weatherproof maintenance of existing buildings, the DOWSIL™ 791/991 series Silicone Weatherproofing Sealants provide reliable aesthetic and protective assurance for modern architecture, backed by proven physical performance and applicator-friendly properties.