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Dried-on mortar over the face of brick is unsightly and can ruin the appearance of a wall. The easiest way to have clean bricks is to prevent mortar splatter during wall construction, but you can also chisel off the mortar once it's dried. For mortar that you can't remove regardless of what you do, using muriatic acid to remove the stubborn mortar may be a good solution. Irrespective of your situation, it's important that you follow the correct procedures and take safety precautions when cleaning mortar off of bricks.

Method 1
Method 1 of 3:

Cleaning off Wet Mortar

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  1. Use a forward lifting and rolling motion with the short edge of your trowel to even out the mortar with the face of the brick. Continue to do this as you lay new bricks to prevent mortar from bunching up and creating large chunks on the bricks.
    • You can also use a large, clean sponge to even out the mortar with the face of the bricks.
  2. The goal is to brush away dust on the face of your brick rather than wiping the mortar dust deeper into the brick. Avoid pressing down on the brush and wipe away from the surface of the brick. Use a back and forth motion until the mortar dust on the face of your wall is removed.
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  3. Set up a scaffold 2 inches (5.08cm) from the wall to prevent mortar splatter. A scaffold should be set up 2 inches (5.08cm) from the wall to prevent mortar splatter at the base of your wall. Scaffold boards that are closest to the wall should be angled away and slightly downward from the wall.
  4. Lay down straw, fabric drop cloths, or plastic sheeting on the base of the wall to prevent mortar drippings from staining the base of your wall. These drop clothes should extend 3 to 4 feet (91.44 cm) from the base of your wall.
    • You can also use plywood or oriented strand board. If any mortar drips on the wooden boards, you can reuse it as long as it didn't get dirty.
  5. If you take all of these precautionary measures, but large clumps of mortar still end up on your wall, you should allow them to dry and then attempt to remove them using the chisel or acid method.
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Method 2
Method 2 of 3:

Removing Dry Mortar with a Chisel

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  1. Ensure that the mortar has had at least 7 days to dry before trying to remove the dried on mortar. Saturating the wall with water before you chisel will make removing the mortar easier and can protect your bricks from being damaged. Fully saturate the brick before you start working with a garden hose or with buckets of water. [1]
  2. Hold the chisel at a 20° to 30° angle against the face of your wall on areas that have built-up mortar. Lightly tap on the end of the chisel and start to break the dried up mortar from off the wall. Start from the top and work your way to the bottom. Continue to work slowly and carefully until most of the mortar is removed from the wall. [2]
    • Break up larger pieces of mortar into smaller more manageable pieces instead of trying to remove it all at once.
    • Lime mortar is easier to remove than cement based mortar using this method.
  3. Go in a back and forth motion over the face of the brick to remove any broken up mortar dust. Try to scrape off any stubborn mortar that wasn't removed from chiseling. Do not spend too much time in one area or you may discolor the brick in that area. [3]
  4. Use a chisel or a hard brush to remove a piece of mortar and take it to the nearest brick supplier. The supplier will be able to match the color and consistency so you can mix more. Mix your mortar and fill in any damaged areas using a mortar bag. Allow the mortar to harden for 20 minutes before shaping it with a jointer tool. [4]
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Method 3
Method 3 of 3:

Using Muriatic Acid to Remove Dried Mortar

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  1. Muriatic acid is very toxic and caustic, so it's important that you follow the proper safety precautions when using it. Wear acid-proof gloves, goggles, closed-toe shoes, protective clothing, and a NIOSH-approved respirator equipped with the appropriate acid-grade filter when working with acid. You can find this safety equipment at the hardware store or online. Lay plastic sheets down at the base of the wall to act as drop cloths for the acid. [5]
    • Keep a box of baking soda around to pour it on yourself if acid splashes onto your skin. Caustic chemicals from the muriatic acid could cause chemical burns.
  2. Read the information and warnings provided with the product that you've purchased. Follow the dilution amounts and process on the back of the packaging. Typically, you'll want to create a solution that is one part muriatic acid to nine parts water.
    • Never mix muriatic acid with other chemicals.
    • Do not use acid for lightly colored or cream-colored bricks. The acid can discolor them and weaken their joints.
  3. [6] Fill an acid-resistant bucket up with water first, then add the muriatic acid. This will prevent splashback which could potentially spray acid onto you.
  4. Before you apply the acid to the wall, it's important that it's fully saturated with water. Applying the muriatic acid directly on a dry brick may damage your wall.
  5. Purchase an acid resistant brush online so that the bristles don't disintegrate while you apply it to the brick. Dip the brush into the acid solution that you created and apply it in a layer over a small portion of the brick that you want to clean. Apply the acid in a small area to make sure that there isn't an adverse reaction with the brick in your wall. [7]
  6. Allow the acid to soak into the mortar on the bricks and break it down. If the acid is working, it will start to bubble and fizz when it comes into contact with the mortar. Do not let the acid fully dry on the brick or it could damage them. [8]
    • If you notice that there is discoloration on the brick, stop using the acid.
  7. Use a medium bristle brush and scrub the face of the brick vigorously. Avoid scrubbing in the joints of the brick or you may weaken the mortar that holds the brick in place. Scrape the sludge that's created from the mortar and acid onto your drop cloth. Continue to scrub until all of the dried on mortar is removed.
  8. As you work, make sure that none of the acid dries to the brick. Dried acid can weaken the brick and discolor it. Always keep a garden hose or a bucket filled with water close by and rinse away the acid after you're done scrubbing away the mortar.
    • Once the acid is thoroughly washed away, store the leftover acid somewhere that children and pets won't be able to reach it.
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Expert Q&A

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  • Question
    How can I remove dry mortar from the bricks in my fireplace without using muriatic acid?
    Anthony "TC" Williams
    Experienced Landscaper
    Anthony "TC" Williams is a Professional Landscaper in Idaho. He is the President and Founder of Aqua Conservation Landscape & Irrigation, an Idaho Registered Landscape Business Entity. With over 21 years of landscaping experience, TC has worked on projects such as the Idaho Botanical Garden in Boise, Idaho. He is a Idaho Registered Contractor and a previously Licensed Irrigator in the State of Texas.
    Experienced Landscaper
    Expert Answer
    If the mortar is lime-based, strong vinegar may help loosen it. If the mortar is concrete-based, try using strong hydrogen peroxide in multiple applications to loosen the mortar.
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      Things You'll Need

      Cleaning off Wet Mortar

      • Trowel
      • Medium-soft bristle brush
      • Drop cloths or plastic sheets
      • Scaffolding
      • Bucket
      • Sponge
      • Light-bristle brush
      • Rags

      Removing Dry Mortar with a Chisel

      • Garden hose
      • Bucket
      • Chisel
      • Hardwire brush

      Using Muriatic Acid to Remove Dried Mortar

      • Medium bristle brush
      • Muriatic Acid
      • NIOSH-approved respirator
      • Bucket
      • Water

      About This Article

      Article Summary X

      To clean wet mortar off bricks, use the edge of a trowel or a large sponge to even out the mortar with the wall face. Then, use a medium-soft bristle brush to rub off any remaining mortar dust. To remove dry mortar, wet down the brick with a garden hose before tapping a chisel at an angle against the face of the wall to remove the excess mortar. Keep reading tips from our Professional Landscaper reviewer to learn how to use muriatic acid to remove dried mortar!

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