DOWSIL™ 791 Weatherproofing Sealant

DOWSIL™ 791 Weatherproofing Sealant

DOWSIL™ 791 Silicone Weatherproofing Sealant is a one-part, neutral- cure, architectural grade sealant. It easily extrudes in any weather and cures at ambient temperature by reaction with moisture in the air to form a durable, flexible silicone rubber seal.


• Ideal for expansion, connection, perimeter and other movement joints

• Neutral cure – suitable for use on coated glass, galvanized steel, masonry and other porous and non-porous substrates

• Extension/compression movement capability of up to ±50 percent of the original joint width

• Excellent weatherability, virtually unaffected by sunlight, rain, snow, ozone

• Excellent unprimed adhesion to a wide variety of construction materials and building components

• Ease of application – ready to use as supplied

• Excellent rheology, low string upon gunning


Please consult the Dow Americas Technical Manual, Form No. 62-1112, for detailed information on state-of-the-art application methods and joint design. Please contact your local Dow Sales Application Engineer for specific advice.


Clean all joints removing all foreign matter and contaminants such as grease, oil, dust, water, frost, surface dirt, old sealants or glazing compounds and protective coatings.

Application Method

Install backing material or joint filler, setting blocks, spacer shims and tapes. Mask areas adjacent to joints to ensure neat sealant lines. Primer is generally not required on nonporous surfaces, but maybe necessary for optimal sealant of certain porous surfaces. A test placement is always recommended. Apply DOWSIL™ 791 Silicone Weatherproofing Sealant in a continuous operation using a positive pressure. (The sealant can be applied using many types of air-operated guns and most types of bulk dispensing equipment. Before a skin forms (typically within 15 minutes), tool the sealant with light pressure to spread the sealant against backing material and the joint surfaces. Remove masking tape as soon as the bead is tooled.


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