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How to Clean Brick with Acid

Ask This Old House mason Mark McCullough demonstrates how to clean soot out of brick using acid


  • Protect the area around the bricks being cleaned. Lay down a drop cloth first to prevent any scratching from materials, then cover that with a plastic tarp.
  • Place the containment sock around the bricks being cleaned on top of the tarp to further contain the mess.
  • Before handling the acidic cleaner, put on rubber gloves and goggles to protect yourself from serious burns.
  • Dry brush the surface of the brick to remove any loose particles.
  • Fill the first bucket with only water.
  • Dip the brush into the bucket of water and dampen the brick until it’s thoroughly soaked.
  • Fill the next bucket halfway with water. Then pour the masonry cleaner into the bucket of water. It’s important to pour the masonry cleaner into the water instead of the other way around to prevent any burns from the acid.
  • Dip a second brush into the masonry cleaner mixture, then gently apply the brush to the brick.
  • Let the brick absorb the cleaner for 3-5 minutes, then use the water brush to scrub any residue off the brick.
  • Repeat this process until the brick is clean. If the desired results are not achieved, strengthen the concentration of the cleaner in the bucket and also scrub a little harder than during the first pass.

The other materials used for this project, including buckets, brushes, drop cloths, gloves, and goggles, can be found at home centers.

Expert advice on this project was provided by MJM Masonry.