The fireplace interior where the fire occurs is called the firebox.
It is made up offirebricksand mortar, which are designed to withstand high heat.
Small gaps in mortar can be repaired with a special high-temperature caulk called refractory caulk.
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It contains silica for heat resistance and is specifically designed for fireplaces.
This fix is a fairly quick, easy, and inexpensive process.
Warning
Refractory caulk, also known as fireplace mortar, is suitable for minor repairs only.
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Significant damage in a firebox can be a serious fire hazard and should not be repaired with refractory caulk.
Vacuum the firebox floor and walls with a shop vacuum to remove all residual ash and debris.
Next, scrape out loose mortar from between the fire bricks using a linoleum knife or putty knife.
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As you work, inspect all of the mortar joints to ensure they are sound.
Thoroughly vacuum the walls and floor of the firebox again.
Slowly force the caulk into the gaps, filling them as deeply as possible.
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It can be easiest to caulk all vertical joints first, followed by the horizontal joints.
it’s possible for you to wear latex or nitrile gloves to keep your hands clean if you wish.
That way, you won’t accidentally reapply the excess caulk where you don’t want it.
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Cure the Caulk
Let the caulk dry as directed by the manufacturer.
Refractory caulk usually cures fully after exposure to fire for one hour.
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