Preparation
- Clean all joints and glazing pockets and make to remove all foreign matter and contaminants including grease, oil, dust, water, frost, surface dirt, old sealants or glazing compounds, and protective coatings.
- Metal, glass and plastic surfaces should be cleaned by mechanical or solvent procedures. Detergent or soap and water treatment are not advised. In all cases where used, solvents should be wiped on and off with clean, oil-and lint-free cloths.
Priming
When applying Dow 799 silicone glass and metal building sealant, priming is not need when applied to most construction materials. Consult Dow for priming recommendations for various substrates if you are not sure. NOTE: Prior to general job use, place a bead of sealant on the substrate material to test for adhesion.
Application
Install back-up 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 non-porous surfaces, but may be necessary for optimal sealing of certain porous surfaces. A test placement is always recommended.
Apply Dow 799 silicone glass and metal building 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. Within 10 minutes of opening up the cartridge, tool the sealant with light pressure to spread the sealant against the backing material and joint surfaces. A tool with a concave profile is recommended to keep the sealant within the joint. Now, after the bead has been tooled, remove all of the applied masking tape. Excess sealant should be cleaned from glass, metal and plastic surfaces while still uncured using a commercial solvent such as isopropyl, xylene, toluene or methyl ethyl ketone. Caution: These solvents are hazardous materials and can cause bodily harm if not handled properly. Please refer to the MSDS for any of these solvent products for further information.
LIMITATIONS
Dow 799 silicone glass and metal building sealant is not recommended for use:
- In below grade or in horizontal joints where physical abuse or abrasion is likely to be encountered
- For structural silicone glazing applications
- In totally confined spaces where sealant cannot cure because of a lack of atmospheric moisture
- On surfaces that will be painted since the paint film will not stretch with the extension of the sealant and may alligator or peel
- On wet or frost-laden surfaces
- On substrates that bleed oil or plasticizers
NOTES:
Dow 799 silicone glass and metal building sealant:
- This product is neither tested nor represented as suitable for medical or pharmaceutical uses.
- May discolor sensitive metals such as copper and brass
- May stress-crack polycarbonate
- Be aware that the shelf life of this silicone sealant is 24 months from the manufacture date that is stamped on each cartridge
- Apply sealant at temperatures as low as -35 degrees F.
