Dowsil silicone sealants
[Dow] Dow produces numerous types of one-part, neutral-cure Silicone materials that can be used as adhesives/sealants. These room temperature vulcanizing (RTV) silicones were introduced in the 1960s and cure upon exposure to atmospheric moisture. There are two type of neutral cure RTV silicones. The first type is an alkoxy neutral-cure that releases methanol upon cure. The alkoxy neutral cure silicones are considered suitable for use on all types of metal without risk of corrosion. The second type is an oxime neutral-cure silicones that releases methyl ethyl ketoxime. These withstand temperature better than alkoxy-cure but can cause stress-cracking in some plastic boards, such as polycarbonate and acrylics.
General properties for Dowsil silicones include:
- Stability over a wide temperature range – When fully cured, most can be used at temperatures ranging from -85° to 599°F (-65° to 315°C).
- Weather resistance – High resistance to UV rays, radiation and weather prevents our products from hardening, cracking, crumbling, drying and becoming brittle.
- Chemical stability – Do not readily degrade, even under long-term exposure to many chemicals and atmospheric pollutants.
- Good bond strength – Provide good adhesion to a wide variety of industrial materials, including glass, ceramics and wood masonry; painted surfaces; and many metals and plastics.
- Low flammability – In fire conditions, silicone adhesives/sealants are reluctant to burn. Many products comply with UL flammability standards.
|Commercial name||Cure type||Applications||Working Properties||Benefits/Risks||Material Analysis||Product website|
|Dowsil 580 Neutral cure||Oxime neutral cure; one component||General Glazing; Weather-sealing applications for windows, doors, glass, metal, masonry||Not recommended for water immersion; do not use on structural glazing; may discolor copper and brass; cannot be painted; not for use on polycarbonates||Testing results||Dowsil 580|
|Dowsil 737 Neutral Cure||Oxime neutral cure; one component||Adhesion to most materials; Adhering plastic moldings to plastic substrates for trim applications; Waterproofing electrical components||Not recommended for water immersion, or use on painted surface; may discolor brass, or copper; may stress craze polycarbonates||MMA 2016; BKM 2017; BKM 2018; BKM 2018; Testing results||Dowsil 737|
|Dowsil 739 RTV||Alkoxy cure with moisture; one component||Adheres well to unprimed metals, ceramics and glass and some plastics;||Does not adhere to Teflon, polyethylene, polypropylene, or highly plasticized plastics or rubbers.||MMA 2016; Testing results||Dowsil 739|
|Dowsil 791 Weatherproof Sealant||Alkoxy cure with moisture; one component; medium modulus||Good for inside display envelope: glass and metal joins; glass and glass joins; Goppion uses black, grey, white due to aesthetic reasons (transparent caulks yellow within 5 years)||MMA 2016; AMNH 2019; MMA 2021; white is unsuitable; Testing results||Dowsil 791|
|Dowsil 795 Building Sealant||Alkoxy cure with moisture; one component; medium modulus||Structural and nonstructural glazing; weather sealing of most common construction materials including glass, aluminum, steel, painted metal, EIFS, granite and other stone, concrete, brick and plastics||Extra thick; skins over too quickly||Not recommended for water immersion, or wet or cold surfaces; not paintable||MMA 2016; MMA 2020; MMA 2021; Testing results||Dowsil 795|
|Dowsil 9-1374 Silicone sealant||Alkoxy cure with moisture; one component||Used for formed in place gaskets; provides strong flexible bond for movable or expanding joints, such as when bonding materials with different thermal expansion rates such as glass to metal, or glass to plastic or metal to plastic||MMA 2016; Testing results||Dowsil 9-1734|
|Dowsil 3145 RTV Mil-A-46146 Adhesive / Sealant||Alkoxy cure with moisture; one component||Sealing openings in modules and housings; Adding mechanical stability to individual components; adheres to glass and nylon||Skin-over time = 15 min; hard to work with; requires experienced person to apply and clean up; viscous, does not flow||Good adhesion cannot be expected on non-reactive metal substrates or non-reactive plastic surfaces such as Teflon, polyethylene or polypropylene.||BKM 2016; BKM 2017; AWNH 2019; Testing results||Dowsil 3145|
|Dowsil 7091 Adhesive Sealant||Alkoxy cure with moisture; one component||Provides strong but flexible bond, such as when bonding materials with differing thermal expansion rates, e.g. glass to metal or glass to plastic||Skin-over time = 15 min; This one has been used in museums||For maximum adhesion, the use of DOWSIL™ 1200 OS Primer is recommended.||BKM 2016; BKM 2017; MMA 2017; AMNH 2019; Testing results||Dowsil 7091|
|Dowsil 993||Two-component, fast cure alkoxy neutral-cure||Good for glass to glass and glass to metal||Working time 10-30 minutes; This one has been used in museums||No primer is needed; Resistant to UV and ozone||Dowsil 993 Structural Glazing Base and Catalyst|
|Silastic 1080 RTV||Alkoxy cure with moisture; one component||Provides reliable, long-lasting bonds with a wide range of substrates, including ceramics, metals, glass and filled plastics,||Long service life, wide operating temperatures, resistance to oils and solvents; water and steam resistant||Testing results||Silastic RTV|
- Wear eye, hands, and respiratory protection.
- SDS: sheets
Literature indicates the sealant has no significant volatile components. Some silicones have curing byproducts of ethanol, peroxides or ketones. Risk to museum collections could occur if an object comes in contact with the sealant causing possible staining or adhesion (if not fully cured).
Resources and Citations
- AIC Conservation Wiki: Caulk Sealants to Seal Exhibit Cases
- Antala: Dow Silicone Selection guide (contains information on 3145 and 7190)
- Americas: Dow Silicon Technical Manual (contains information on 791, 795 and 993)