What Is DOWSIL Used For
DOWSIL is a brand of silicone sealants, not one product. The grade decides the job: structural glazing, weather sealing, or sealing stone and concrete facades.
DOWSIL is Dow's line of silicone sealants, and the name covers several different products. What each one is used for depends on the grade. DOWSIL 995 is a structural glazing sealant for bonding glass and metal. DOWSIL 791 and 795 are weatherproofing and building sealants for curtain wall, facade, and construction joints. DOWSIL 790 is an ultra-low-modulus sealant for natural stone, masonry, and concrete.
So the honest answer to what DOWSIL is used for is: sealing and bonding joints in commercial glazing and building envelopes.
The grades, and what each one does
DOWSIL 995 is a one-part, neutral-cure structural sealant. Dow describes it as designed specifically for structural bonding of glass and metal in factory or field situations, and it is used in silicone structural glazing and protective glazing. It cures to an elastomeric rubber and has excellent unprimed adhesion to coated, enameled, and reflective glass, and to anodized and coated aluminum including most fluoropolymer paints such as Kynar. Its joint movement capability is ±50 percent.
DOWSIL 791 is a one-part, neutral-curing, low-modulus silicone for general glazing and weather sealing in curtain wall and building facades. Dow lists it for expansion, connection, perimeter, and other movement joints. It conforms to ISO 11600-F&G-25LM and carries a ±50 percent joint movement capability. Application temperature is +5 to +40°C.
DOWSIL 795 is a one-part, neutral-cure, architectural-grade building sealant. Dow lists structural and nonstructural glazing, structural attachment of panel systems, panel stiffener applications, and weather sealing of common construction materials including glass, aluminum, steel, painted metal, EIFS, granite and other stone, concrete, brick, and plastics. It also carries a ±50 percent joint movement capability and meets Canadian Specification CAN2-19.13-M82.
What changes the answer
Three things decide which DOWSIL grade fits: what the sealant has to stick to, whether the joint is structural or just weather sealing, and whether the substrate is sensitive to staining.
Structural versus weather sealing is the first split. DOWSIL 995 and 795 are both listed for structural glazing, but 795's sheet says it should not be used in structural applications without prior review and approval by your local sales application engineer. DOWSIL 791 is not recommended for structural glazing or insulated glazing at all. If the joint carries load, that is a design question, not a shelf pick.
Substrate is the second. DOWSIL 790 is the one for natural stone, porous stone, masonry, and concrete facades. Dow describes it as low-staining and plasticizer-free, suitable for porous substrates, with excellent unprimed adhesion to masonry, concrete, and natural stone. Its extension/compression capability is +100/-50 percent, and it conforms to ISO 11600F-25LM. If you are sealing granite or limestone and staining matters, that is the grade to look at.
Where DOWSIL stops
Every DOWSIL sheet in this set carries limitations, and they matter more than the benefits when you are choosing.
None of these are for continuous immersion in water. DOWSIL 995, 790, and 795 all list that restriction. DOWSIL 791 is not recommended for submerged joints.
Is DOWSIL 100% silicone?
The DOWSIL grades in this set are one-part silicone sealants. DOWSIL 995 is a one-part, neutral-cure elastomeric sealant. DOWSIL 791 is a one-part, neutral-curing, low-modulus silicone. DOWSIL 795 is a one-part, neutral-cure, RTV silicone. DOWSIL 790 is a one-part, neutral-cure silicone. They are silicone products, but they are not interchangeable — each grade is formulated for a different job.
Can I use DOWSIL for a bathroom or shower?
DOWSIL 995, 790, and 795 all list continuous immersion in water as a limitation, and DOWSIL 791 is not recommended for submerged joints. For a tub or shower joint, use a sealant rated for wet areas.
Can DOWSIL be painted?
DOWSIL 995 says it should not be applied where painting of the sealant is required, because the paint film may crack and peel. DOWSIL 795 says it should not be used if the sealant is intended to be painted, because paints do not typically adhere to most silicone sealants. DOWSIL 790 says it should not be applied to surfaces that will be painted after application.
What is the difference between DOWSIL 791 and 795?
Both are neutral-cure silicone building sealants with ±50 percent joint movement capability, but they are aimed at different work. DOWSIL 791 is a low-modulus weatherproofing sealant for general glazing and weather sealing in curtain wall and building facades, and Dow does not recommend it for structural glazing or insulated glazing. DOWSIL 795 is an architectural-grade sealant listed for both structural and nonstructural glazing and for weather sealing of common construction materials.