Step 1: Prep work
The bonding surfaces on both new and existing work must be clean and dry. Wash away all foreign matter and contaminants that could prevent proper adhesion. Dow 732 multi-purpose acetoxy RTV silicone sealant will adhere to cured silicone sealant when using a prep solvent wipe to remove any existing dirt.
Wipe down all surface areas using a clean, oil-free rag that is saturated with solvent such as xylol, toluol or methyl ethyl ketone. Due to the hazardous nature of these products, proceed with caution by always using protective gloves and a high quality breathing mask. Clean metal, glass and plastic surfaces by either mechanical or solvent procedures. Never clean surfaces with soap, detergent or any water-based cleaner. Wipe solvents on with a clean, oil and lint-free absorbent cloth. Remove the solvent before it begins to dry using a clean, dry cloth. Make sure that you do not saturate the surface with more solvent than is necessary. Also ensure that visibly clean surfaces are not left with a thin film of construction dust.
Step 2: Priming
Priming is only recommended for a few applications such as certain metals, plastics, paints and various rubber materials, to ensure proper adhesion.
Step 3: Masking
Be sure to take the time to mask adjacent surface areas in order to create neat sealant lines. Also, be careful to remove all masking before the skin begins to form.
Step 3: Method of Application
Dow acetoxy sealants can be applied directly from the caulking cartridge with either an air-operated or a regular hand-operated cartridge gun. Be careful not to break the cartridge seal until you are ready to start. The clock starts ticking once the nozzle is clipped! Apply Dow 732 to one of the targeted surfaces that you have prepared, then quickly cover with the other substrate that is to be bonded. When exposed to moisture, the newly applied silicone sealant will begin to skinover. All tooling needs to be completed before this skin formation begins. The targeted surface can be easily tooled with a spatula or similar device. The adhesive sealant will be tack-free in less than 45 minutes.
Step 4: Curing time
After the skin forms, the cure continues outward in from the surface area. After about 24 hours (at room temperature and 50% relative humidity) Dow 732 clear multi-purpose acetoxy RTV silicone sealant will cure to a depth of about 3mm. Deeper sections, especially when moisture in the air is minimal or humidity is lower; will take longer to completely cure. Before handling and packaging your bonded components, it is recommended by Dow, to give sufficient time to ensure that the integrity of the adhesive seal is not affected.
Step 5: Clean-Up
Remove any excessive silicone adhesive with a dry paper towel immediately after the masking tape has been removed.
Storage
When Dow 732 is stored in its original, unopened cartridge at or below 90 degrees F, this silicone sealant will have a shelf life of 30 months from date of manufacture as printed on the cartridge as the "Use By" date. All cartridges should be kept sealed when not in use. After a cartridge has been clipped opened, a plug of cured material will form in the nozzle or tube tip during storage. When ready to uyse again, unscrew the nozzle and remove this cured plug. The remaining sealant will be ready to use.
LIMITATIONS
This product is neither tested nor represented as suitable for medical or pharmaceutical uses.
