How to clean old bricks from mortar: effective ways

The disadvantage of recycling old bricks is that they are often spoiled by various substances. You have to remove hardened mortar, dirt, mold, and other stains. Fortunately, refinishing old bricks is easier than it might seem at first glance.

If you try to lay uneven old bricks and ignore the cleaning stage, you risk getting a very unstable wall as the new mortar does not adhere well to the old, dried and hardened material. House Digest explained how to clean old bricks from mortar.

Some professional building organizations warn against using old bricks in large-scale construction projects without thorough strength testing. According to a 2020 paper published in Developments in the Built Environment, the compressive strength of reclaimed bricks ranges from 4.8% to 40%. It is difficult for the average person to perform this level of testing at home. However, old bricks can be used in small renovation projects.

How to clean old bricks

You'll need a hammer, cold chisel, an axe, a trowel, or even just a piece of metal to remove the mortar. You can also use a pneumatic hammer drill with a bit or specialized motorized equipment, such as a scraper or a vibrating plate.

Lime mortar is easier to remove than its cement-based counterpart, so you can use a simple hand tool in this case. A stiff-bristled brush or wire brush will also come in handy. Don't forget to wear gloves and safety glasses.

Take a brick, find the largest piece of mortar, and hit it with the sharp or percussive edge of the tool of your choice. If you are using a hammer drill, set the switch to the "hammer drill only" position.

Some parts may require more than one blow. After the largest pieces have been removed, place the brick on a flat surface and use the tool to scrape off the remaining mortar. Remove dust with a stiff-bristled brush.

If you notice stains, the bricks need to be cleaned well. Vinegar is sometimes recommended as it is a natural ingredient that will remove moss on the surface, for example.

Hydrochloric acid diluted in water will be the best solution at this stage. Take care of your personal safety. Wearing gloves, goggles, a long-sleeved shirt and long pants, pour the acid into the water (never the other way around) in a 1:3 or 1:10 ratio or according to the manufacturer's instructions. Place the bricks in the solution and leave them for 20 minutes.

Rinse them in fresh water, cleaning them at the same time. Air dry the bricks and then carefully inspect them to decide if you need to repeat the cleaning process. You can also spray the solution on each side of the brick with a garden sprayer.

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