DOWSIL™ 736 Heat Resistant Sealant is a one-part, nonslumping paste that cures to a rubbery solid at room temperature on exposure to water vapor in the air. This silicone product is formulated to perform at temperatures ranging from -65 to 260°C (-85 to 500°F) for continuous operation and to 315°C (600°F) for intermittent exposure. It can be used for numerous sealing and bonding applications.
• Will not sag or run
• May be applied overhead or on side walls
• May be used in applications with continuous exposure to 260°C (500°F) and intermittent exposure to 315°C (600°F)
DOWSIL™ 736 Heat Resistant Sealant is supplied ready to use. Under pressure, it flows readily from its container. The paste-like consistency makes it easy to work; a spatula or wooden paddle can be used for tooling the surface.
The cure progresses inward from the surface when exposed to humidified air. At 77°F (25°C) and 50 percent relative humidity, the sealant forms a tack-free skin within 17 minutes. Tooling is not practical after the skin begins forming and should be completed within five minutes after application even though this may require alternate periods of applying and tooling. If masking tape is used to mark off an area, it should be removed immediately after tooling.
Cure time is affected by relative humidity, degree of confinement and cross-sectional thickness of the sealant. Sections up to 3 mm [1/8 inch] thick become rubbery solids in about 24 hours at 25°C (77°F) and 50 percent relative humidity. Less moisture content reduces the time required slightly. In 24 hours, sections up to 3 mm [1/8 inch] thick cure to a rubber.
In applications where DOWSIL™ 736 Heat Resistant Sealant may be partially or totally confined during cure, the time required for proper cure is generally lengthened by the degree of confinement. It is possible, with absolute confinement, that cure will not be completed. Metal-to-metal bonds should not overlap more than one inch. Every application involving confinement during cure should be thoroughly tested before use. Curing time increases with the thickness of the sealant
1. Thoroughly clean and degrease metal and plastic surfaces using DOWSIL™ OS (Ozone Safe) Fluids or another suitable solvent. Rubber surfaces should be roughened with sandpaper, then wiped with DOWSIL OS fluids or another suitable solvent. Follow all precautions given on the solvent container label.
2. For stronger, more uniform bonds, apply a thin film of DOWSIL™ 1200 Prime Coat or DOWSIL™ P5200 Adhesion Promoter to all surfaces except rubber and silicone rubber. Allow to air-dry for 30 t
Note: DOWSIL™ 1200 Prime Coat or DOWSIL™ P5200 Adhesion Promoter are flammable and are not suitable for use in food contact applications. Keep away from heat, sparks and open flames. Use only with adequate ventilation.
3. Apply DOWSIL™ 736 Heat Resistant Sealant to the prepared surface in a uniform thickness. In those cases where the sealant is to be used between two surfaces, put the second surface in place, using enough pressure to displace the air but not the sealant
4. Let the unit stand undisturbed at room temperature until cured.
Using DOWSIL™ 736 Heat Resistant Sealant in sealing applications follows approximately the same step-by-step procedures as outlined for bonding applications. After preparing the surfaces and priming where required, the sealant is applied by forcing it into the joint or seam to obtain full contact between the sealant and the surface.
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