DOWSIL™ 791 Silicone Weatherproofing Sealant

DOWSIL™ 791 Silicone Weatherproofing Sealant is a one-part, neutral-cure, architectural-grade sealant designed for general weathersealing in both new construction and renovation applications. It is manufactured by Dow, an American multinational chemical company. This sealant is ideal for sealing and weatherproofing perimeter joints, curtainwall joints, mullion joints, metal panel systems, and other construction joints. It offers excellent adhesion to most common building substrates, including glass, aluminum, steel, painted metal, stone, and masonry.

Features & Benefits

• Excellent adhesion: It offers excellent adhesion to a wide variety of building substrates, including glass, aluminum, steel, painted metal, stone, and masonry. This ensures a long-lasting and reliable seal.
• Weather resistance: This sealant is designed to withstand harsh weather conditions, including exposure to UV radiation and temperature extremes. It can maintain its performance in both hot and cold environments, making it suitable for use in a variety of climates.
• Easy application: It is a one-part sealant that is easy to apply. It can be applied using standard caulking guns and requires no mixing or special preparation.
• Good tooling properties: This sealant has good tooling properties, which means that it can be easily shaped and smoothed to achieve a neat and uniform seal. This ensures a professional-looking finish and helps to prevent air and water leaks.
• Compatibility: It is compatible with a wide variety of building materials and can be used in combination with other sealants, adhesives, and coatings.

Applications

Some of the common applications include:

• Perimeter sealing: This sealant can be used to seal gaps and joints around the perimeter of windows, doors, and other building openings. It can help to prevent water and air infiltration and improve the energy efficiency of the building.
• Curtainwall joints: DOWSIL™ 791 Silicone Weatherproofing Sealant can be used to seal joints in curtainwall systems. It offers excellent adhesion to metal, glass, and other building materials, and can help to prevent leaks and improve the weather resistance of the system.
• Expansion joints: This sealant can be used to seal expansion joints in concrete, brick, and other building materials. It can help to accommodate movement and prevent water infiltration and other issues that can arise due to temperature changes and building settling.
• Roofing: It can be used to seal gaps and joints in roofing systems, including metal roofs, flat roofs, and sloped roofs. It can help to prevent leaks and extend the life of the roof.
• Masonry: This sealant can be used to seal gaps and joints in masonry walls, including brick, concrete, and stone. It can help to prevent water infiltration and improve the weather resistance of the wall.

How To Use

Here are some general guidelines for using DOWSIL™ 791 Silicone Weatherproofing Sealant:

1. Surface Preparation: The surface should be clean, dry, and free from dust, oil, and other contaminants that may affect adhesion. Use a solvent like isopropyl alcohol to clean the surface if needed. Make sure the surface is completely dry before applying the sealant.
2. Cut the nozzle: Cut the nozzle of the sealant tube at a 45-degree angle to the desired bead size. It is recommended to cut the nozzle a little smaller than the joint width.
3. Apply the sealant: Apply the sealant in a continuous bead along the joint, making sure that the sealant contacts both sides of the joint. Use a caulking gun for application.
4. Tooling: Tool the sealant immediately after application using a caulking tool or a spatula to achieve a smooth, neat finish. This will also ensure that the sealant adheres well to the substrate.
5. Clean up: Clean up any excess sealant immediately using a solvent like isopropyl alcohol. Do not allow the sealant to skin over before tooling.
6. Cure time: Allow the sealant to cure completely before exposing it to weather. The cure time may vary depending on the thickness of the sealant and environmental conditions.
7. Maintenance: Regular inspection and maintenance are recommended to ensure the long-term performance of the sealant.

Application Method

DOWSIL™ 791 Silicone Weatherproofing Sealant can be applied using a standard caulking gun. Here is a general application method:

1. Prepare the surface: Ensure that the surface is clean, dry, and free from any contaminants such as dust, oil, and debris that may affect adhesion. You can use a solvent like isopropyl alcohol to clean the surface if needed. Make sure the surface is completely dry before applying the sealant.
2. Cut the nozzle: Cut the nozzle of the sealant tube at a 45-degree angle to the desired bead size. It is recommended to cut the nozzle a little smaller than the joint width.
3. Load the sealant: Load the sealant tube into the caulking gun and make sure that the plunger is seated firmly against the tube's end.
4. Apply the sealant: Apply the sealant in a continuous bead along the joint, making sure that the sealant contacts both sides of the joint. Use a consistent rate of application to ensure a uniform bead.
5. Tooling: Tool the sealant immediately after application using a caulking tool or a spatula to achieve a smooth, neat finish. This will also ensure that the sealant adheres well to the substrate.
6. Clean up: Clean up any excess sealant immediately using a solvent like isopropyl alcohol. Do not allow the sealant to skin over before tooling.
7. Cure time: Allow the sealant to cure completely before exposing it to weather. The cure time may vary depending on the thickness of the sealant and environmental conditions.

Usable Life and Storage

Usable life: The usable life of DOWSIL™ 791 Silicone Weatherproofing Sealant is typically 12 months from the date of manufacture when stored in unopened containers at or below 27°C (80°F). However, the usable life may be shorter if the sealant has been exposed to moisture or extreme temperatures.

Storage: Store DOWSIL™ 791 Silicone Weatherproofing Sealant in a cool, dry place away from sources of heat and direct sunlight. Keep the sealant in the original, unopened container until ready to use. Do not store the sealant at temperatures above 32°C (90°F), as this can cause the product to cure prematurely.

Limitations

Here are some common limitations:

1. Substrate compatibility: It may not be compatible with all substrates. Some substrates, such as some plastics and some metals, may require a primer or other surface preparation before application. It is important to check the manufacturer's recommendations and perform a compatibility test before use.
2. Joint design: The joint design may also affect the performance of the sealant. Joints with excessive movement or high stress may require a different type of sealant or a different joint design altogether.
3. Cure time: The cure time of DOWSIL™ 791 Silicone Weatherproofing Sealant may be affected by factors such as temperature, humidity, and joint depth. It is important to allow the sealant to cure fully before exposing it to weather or other stresses.
4. Paintability: While DOWSIL™ 791 Silicone Weatherproofing Sealant can be painted, it may not be compatible with all paints or coatings. It is important to check the manufacturer's recommendations and perform a compatibility test before application.