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Choosing and using fireplace sealants

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Fireplace sealants are suitable for repairing and sealing cracks, seams, and joints in typical brick chimneys and fireplaces, and you can also use them to seal concrete fireplaces. Since they are exposed to searing heat, fireplace sealants must be able to withstand extreme temperatures. Read on to learn about these specialty sealants.

How to choose the right fireplace sealant

The fireplace sealant you select must be able to bond to the materials in and around your fireplace. That means if you are sealing a joint between a concrete fireplace and a brick wall, your fireplace sealant has to form bonds with both materials.

Your fireproof sealant must be able to withstand very high temperatures. Many fireplace sealants specify maximum application temperatures, so use this information as a guide. Try to find out how hot your walls or fireplace will get. A good rule of thumb: the higher the temperature a sealant can take, the more likely it will be appropriate for your project.

While this text focuses on fireplace sealants, it is worth mentioning that there are also products for creating exterior seals around chimneys, such as Loctite PL S30 Polyurethane Roof and Flashing Sealant.

Applying fireplace sealant

These instructions serve as general guidelines since application processes vary from product to product. Always read your manufacturer’s instructions for more on your fire sealant’s curing time, application temperature, and other important information.

Gather materials. You need a sealant gun, cleaning material, a putty knife, and water. Also, play it safe: wear gloves and goggles for extra protection.

Prepare surfaces. They must be clean (free of dust, grease, and other contaminants) and dry. However, you may need to moisten joints later on. Some Fireplace sealants are highly alkaline, surroundings have to be covered, hands and eyes must be protected. Always check the usage instructions and prepare surfaces accordingly.

Apply fireplace sealant. Load the fire sealant cartridge into the gun and cut the tip of the cartridge or application nozzle to the desired opening width. Slightly moisten the joints if indicated in the product information, then inject the fireproof sealant evenly into them. Even out the fireplace sealant immediately with a wet smoothing tool, if necessary.

Clean-up. Immediately remove wet stains with water. You must remove cured fireplace sealant mechanically, like using a sharp blade to cut it away.

Let it cure. Let your fire sealant dry according to the instructions.

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