Not for exterior use. Apply 1/16 - 1/8" thick!

Fireplace Mortar Caulking Cartridge in Buff Color

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Repair minor cracks and imperfections in your fireplace refractory with our 10.3 Fluid Ounce Fireplace Mortar in Buff! This heat resistant mortar is ideal for improving the look of your indoor firebrick, and it can be fired as soon as you apply it! After it cures at 1200°F, it will withstand temperatures up to 2000°F and will become as hard as the surrounding firebox to ensure a quality, long-lasting finish! The convenient caulking cartridge can cover up to 99 feet and is versatile enough to patch firebricks or repair masonry on areas 1/8" or smaller--perfect for most any fireplace mortar repair! Once fully hardened you can keep the buff color or paint it to perfectly match your current masonry. Meets ASTM E-136 and E72 non-combustibility standards.

Remember to check out our "Silicone & Caulking Tips: DIY Like a Pro!" below to see if we have any suggestions to help make your DIY project easier. If you have any questions, we’re happy to help! Give Fast Replacement Glass a call at 1-888-986-1535, start a live chat, or email us at [email protected].

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  • To use:
    • Burn a low fire to dry the fireplace mortar.
    • Heat under extreme heat to cure.
    • This mortar is rated for indoor use only. 
    • For large repairs (exceeding 1/8" areas), a castable refractory cement is highly recommended.

How to caulk like  pro!Silicone & Caulking Tips: DIY like a Pro!

  1. Product cartridge fits into a standard caulking gun. For clean application, cut the cartridge tip near the end, at an approximate 45° angle.
  2. Ensure that the working surface is clean, dry, and free of debris. Have some damp cloths or a roll of paper towels within reach. Lay down newspaper to protect carpet/flooring from possible drips.
  3. To lay a professional bead, hold the caulking gun at 45°. Spin the cartridge tube so the longest part of your tip is aligned with the top side of the caulking gun.
  4. Beginning at the highest point of your working area, slowly and gently squeeze the trigger and drag the gun to lay an even bead (about 1/8"). 
  5. For a clean job, remember that "A little goes a long way!" Try to be consistent when laying a bead - you can always go back and add more material later.
  6. As you near the end of the working area, release the trigger (or press the release lever) to stop the flow of material.
  7. After applying the material, let it cure for the indicated amount of time (at room temperature) before using your appliance.
Size: 10.3 fl oz cartridge
Color: Buff
Temperature Rating: 2000°F (1093°C)
Certification: ASTM E-36 and E72 non-combustibility standards


Estimated Lead Time:

Please allow 1 week for shipping unless otherwise specified. 

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Last updated on October 13th 2021.
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