DOWSIL 791 Weatherproofing Sealant
DOWSIL 791 is a one-part, neutral-curing, low-modulus silicone sealant for general glazing and weather sealing in curtain walls and building facades. Dow does not recommend it for structural glazing or insulated glazing.
DOWSIL 791 Weatherproofing Sealant is a silicone sealant from Dow. Dow lists it for general glazing and weather sealing in curtain wall and building facades, expansion, connection, perimeter, movement joints. Dow gives the application temperature as +5 to +40 °C, which the product and the surface both have to meet on the day. Cranco carries it, and which counter has it on the day changes, so ask at the counter.
DOWSIL 791 is a one-part, neutral-cure silicone sealant made by Dow for weather sealing curtain wall and building facades, and for expansion, connection, perimeter and movement joints. It is rated at 50% movement, it skins in 20 minutes and it is tack-free in 30 minutes.
Cranco carries Dow at Concord, Barrie and Mississauga. Call the branch to confirm the colour and size in stock, and the price.
FEATURES AND BENEFITS
- Available in multiple colors and cures to form flexible and durable joints.
- Sustainability: Low embodied carbon DOWSIL™ Silicone.
- Highly resistant to weather, UV and temperature extremes.
- Weatherproofs substrates such as glass, aluminum, steel, painted metal, EIFS, granite & other stone, concrete, brick, plastic.
- Ready to use as supplied with all-temperature gunnability, easy tooling and low-odor curing.
- Excellent unprimed adhesion to a wide variety of construction materials and building components, including anodized, alodined, most coated and many Kynar painted aluminums.
- One-part, neutral-curing, low-modulus silicone sealant.
What is DOWSIL 791 used for?
General glazing and weather sealing in curtain wall and building facades, and expansion, connection, perimeter and movement joints. Dow rates it at 50% movement and sets the application range at 5 to 40 °C.
How long does DOWSIL 791 take to dry?
It skins in 20 minutes and is tack-free in 30 minutes. Dow gives the cure in depth rather than in days: 2.0 mm at one day and 4.0 mm at three days, measured at 23 °C and 50% relative humidity. A deeper bead takes proportionally longer.
How do you apply DOWSIL 791?
Dow sets the application range at 5 to 40 °C, and it ships in a 310 mL cartridge and a 600 mL sausage. Dow rules the sealant out on bituminous substrates, on natural rubber, chloroprene and EPDM, and on materials that bleed oils, plasticizers or solvents. On porous stone such as concrete, marble or granite Dow warns of bleeding and asks for a test on the actual substrate.
Can you paint over DOWSIL 791?
Dow's sheet for 791 states no paintability line. Dow does put it plainly on its own 795 sheet, that paints do not typically adhere to most silicone sealants, so treat DOWSIL 791 the same way until the counter confirms it with Dow. Where the joint has to take paint, TremFlex 834 is the acrylic latex Cranco stocks.
Is DOWSIL 791 waterproof?
It weather seals a facade joint, and Dow's sheet calls it resistant to ozone, ultraviolet radiation and temperature extremes. Dow rules it out for submerged joints and for joints where physical abuse or abrasion is likely, and says it is not for structural glazing or insulated glazing. Those three jobs take a different product.
Which standards does DOWSIL 791 carry?
SNJF F&G-25E, ISO 11600-F&G-25LM, DIN 18540 Class F and the EN 15651 CE mark. Those are European approvals. The sheet Cranco holds names no ASTM or CAN/CGSB number for 791, so where a Canadian spec calls for one, DOWSIL 795 carries ASTM C920 and its own page names the CAN2 number.
Where can you buy DOWSIL 791?
At Cranco's counters in Concord, Barrie and Mississauga. The addresses, phone numbers and hours are further down this page. Call ahead and the counter will tell you which colour and size they have that day.
Limitations from Dow
Do not use DOWSIL™ 791 Silicone Weatherproofing Sealant on bituminous substrates, substrates based on natural rubber, choloroprene or EPDM or on building materials and flexible plastics which might bleed oils, plasticizers or solvents. Do not use DOWSIL™ 791 Silicone Weatherproofing Sealant in a totally confined space because the sealant requires atmospheric moisture to cure. DOWSIL™ 791 Silicone Weatherproofing Sealant is not recommended for use on submerged joints or in joints where physical abuse or abrasion is likely to occur. Bleeding can occur on porous substrates such as concrete, marble, granite or other natural stones. On sensitive substrates, specific testing should be carried out. This product is not suitable for areas where food contact is likely. DOWSIL™ 791 Silicone Weatherproofing Sealant is not recommended for structural glazing or insulated glazing applications. This product is neither tested nor represented as suitable for medical or pharmaceutical uses.
Branches
Call the branch to confirm what it has in stock today, and the price.
Colours
Dow names its colours on the chart below.
Call the branch for the colour you need.
Data sheet
- DOWSIL 791 data sheet Dow, PDF