DOWSIL 790 Silicone Building Sealant
A one-part, ultra-low-modulus, neutral-curing silicone elastomeric sealant for use in high-movement weathersealing applications.
DOWSIL 790 Silicone Building Sealant is a silicone sealant from Dow. Dow lists it for joints between natural stone, curtainwall and mullion joints, expansion and control joints. It does not take paint, so a bead that has to be finished needs another product. Cranco carries it, and which counter has it on the day changes, so ask at the counter.
DOWSIL 790 is Dow's ultra-low-modulus silicone for masonry, concrete and natural stone facades. It takes +100/-50% extension and compression under ASTM C719, the widest figure in this catalogue under that test, and it meets ASTM C920 Type S Grade NS Class 100/50. Tremco's Dymonic 100 reaches the same +100/-50% under a modified C719 and ±50% under the standard one.
Dow tests it at no staining on various substrates under ASTM C1248, and gives it unprimed adhesion to masonry, concrete and natural stone. 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
- Low-staining and plasticizer free, suitable for porous substrates.
- Excellent performance even in building joints that experience extreme movement.
- Extension/compression capability of +100/-50 percent.
- Conforms to ISO 11600F-25LM.
- Excellent unprimed adhesion to masonry, concrete and natural stone substrates.
- Easy application over a wide temperature range.
- Excellent weathering properties and resistance to sunlight, rain, snow, and temperature extremes.
What is DOWSIL 790 used for?
Joints between natural stone, curtainwall and mullion joints, expansion and control joints, and precast concrete panel joints. Dow points it at sensitive natural stone and porous stone facades, where a staining sealant shows on the face of the building.
How much movement does DOWSIL 790 take?
Plus 100 and minus 50 percent extension and compression under ASTM C719, and the highest ISO 9047 category at plus or minus 25 percent. Its ASTM C920 rating is Class 100/50. For comparison, DOWSIL 795 and 995 are Class 50 and DOWSIL 1199 is Class 25.
Does DOWSIL 790 stain stone?
Dow's ASTM C1248 result on various substrates is none, and it describes the sealant as low-staining and plasticizer free. That is the reason it is the one Dow points at sensitive natural stone and porous stone facades.
How fast does DOWSIL 790 cure?
It skins over in 9 minutes and is tack free in 31 minutes at 23 °C and 50% relative humidity. The cure runs 2.8 mm deep after one day and 5.8 mm after three.
Can you paint DOWSIL 790?
Dow's limitations put surfaces that will be painted after application on the list of places not to use it. Dow's own explanation follows in the same sentence: the paint film will not stretch with the extension of the sealant and may crack and peel, and most likely will not adhere to the sealant. On a joint moving +100/-50% the paint has the furthest to stretch.
Where should you not use DOWSIL 790?
Dow rules out structural applications, below-grade work, brass and copper, surfaces continuously immersed in water, interior penetration firestop, and totally confined spaces. For a structural bond DOWSIL 995 is the one Dow rates for it.
What colours does DOWSIL 790 come in?
Black and gray. Dow publishes no package size for it on the sheet Cranco holds, and gives a shelf life of 12 months from manufacture when stored at or below 32 °C. Call the branch for the sizes it carries.
Where can you buy DOWSIL 790?
At Cranco's counters in Concord, Barrie and Mississauga. The addresses, phone numbers and hours are further down this page.
Limitations from Dow
should not be applied in structural applications, below grade, on brass/copper, to surfaces continuously immersed in water, as interior penetration firestop, in totally confined spaces, or to surfaces that will be painted after application ("The paint film will not stretch with the extension of the sealant and may crack and peel and most likely will not adhere to the sealant.")
Branches
Call the branch to confirm what it has in stock today, and the price.
Colours
Dow publishes a colour range for this product.
The chart below is the DOWSIL 795 colour chart. Dow makes DOWSIL 790 in black and gray.
Call the branch for the colour you need.
Data sheet
- DOWSIL 790 data sheet Dow data sheet, PDF