Cleaning Mortar From Bricks - How to Clean Mortar and Cement From Reclaimed Bricks so They can be Recycled

Summary: In this DIY project guide we will show you how to clean mortar from bricks including reclaimed bricks and recycled bricks so that they can be reused. Learn the various techniques involved in cleaning mortar and cement from bricks that include using a hammer, bolster and a wire brush and also additionally how you can use Muriatic acid to remove old mortar from bricks. We will also show you how to use this acid safely so that you do not injure yourself or damage the bricks as this is pretty potent stuff.

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We wonder how many of you have clicked into this project to find and easy way of how to clean mortar from bricks and avoid having to do this awful job.....?

Sorry, there isn't one! Unless, like us, you get someone else to do it!

Cleaning mortar with a bolster

Cleaning mortar with a bolster and hammer

Why Would you Want to Clean Bricks?

There are several reasons why old used bricks will need to be cleaned but in the majority of cases it will probably be down to the construction of an extension and the fact that it needs to blend with the existing property its being joined to, or just down to the fact that you like a particular style or colour of brick.

In the case of a new property, it may be stipulated by the local planning department that it needs to match the look of existing properties in the area and so bricks of the same style will need to be sourced.

When it comes to sourcing bricks these are known as reclaimed bricks. In most instances these bricks will come from demolition and restoration jobs and there are specialist companies that supply bricks of this type on mass.

Reclaimed bricks

Selection of reclaimed bricks - Image courtesy of authentic-reclamation.co.uk

Most companies wil either supply them cleaned or uncleaned. The cleaned bricks will have had a professional sprucing up, removing old mortar and stains whereas uncleaned bricks are bought as they come, normally covered in mortar and dirt meaning it's up to you to clean them.

As you may imagine the cleaning process is very labour intensive so cleaned bricks are a fair bit more expensive than non-cleaned.

How to Clean Mortar From Bricks

If you want to remove mortar excess and spills from bricks then there is really only two ways to do this:

  • Using a hammer and bolster and a wire brush
  • Using a watered down solution of Muriatic acid

If you are lucky enough to have bricks that have a lime based mortar on them this job will be considerably easier as the lime mortar is a bit softer than sand and cement based mortar.

Using a Hammer, Bolster and Wire Brush for Cleaning Mortar From Bricks

This is pretty much as mundane as it sounds - Firstly find yourself a nice stable place to work on. An ideal base is a Workmate os something similar as you can make use of the vice section to clamp your brick solid and you won't have to stoop over as much.

Black and Decker Workmate

Black and Decker Workmate

If you don't have a Workmate, a bench or old table should be fine. You can clamp the brick down with a suitable G-clamp or ratchet clamp. Don't apply too much pressure as some older bricks can be quite brittle and they will split if too much pressure is applied.

Failing the availability of a Workmate or bench then you will have to locate a fixed or solid item to steady your brick against, as in the image above, a concrete step is ideal but it's a good idea to put a solid piece of timber inbetween the brick and the step as you don't want to damage the step.

Also, if you have your brick resting on a solid surface put something under it! An old piece of carpet or similar is ideal. As the hammer and bolster strike the brick this can produce a shock wave and if there is nothing below the brick to absorb the impact then it will take the full force and likely split.

With a suitable location or bench sorted, clamp your brick or butt it up to a solid surface with the mortar to be removed facing up towards you.

Take your bolster and position it at the base of the mortar on top of the brick and hold it at around a 25 - 30° angle. Hit the striking plate on the bolster with the hammer until the mortar starts to loosen and come off. Continue moving the bolster along the face of the brick, removing large chunks fo mortar.

Bolster with hand protector

Brick bolster with hand protector on grip

Again, be careful about how hard you strike the brick and at what angle as you don't want to take any chunks out or split it.

Use the bolster method to remove as much mortar as you possibly can. Once you have removed as much as you can without damaging the brick it's time to break out the wire brush.

You can use this to scrub as much of the remainder of the mortar off of the brick. Again, be careful not to dwell too long in one place or press too hard as this can damage the brick.

Block wire brush

Block style wire brush

This should remove a fair amount of the remainder except a few stubborn parts and you may also be left with a white stain. The next step should help you remove these if you wish.

As always, make sure that you wear safety goggles, thick gloves and some old clothes. Not only is this a pretty messy job, mortar splinters and fragments can fly off in all directions so be aware of this.

Using a Muriatic Acid Solution to Clean Mortar From Bricks

Although it is possible to bypass the above step and just use acid to remove the mortar we wouldn't recommend it. The volumes and concentration you would need to remove a whole mortar bed section from a brick (and indeed numerous bricks) would cost a fortune and most likely damage each brick significantly.

With this in mind it's best used after you have removed as much mortar as possible by using the hammer and bolster method and then cleaned up with a wire brush and then just use this step on any subborn areas or stains.

Muriatic acid is a a type of hydrochloric acid and if you know your acids you will know that this is a potent one so be careful it burns!

Muriatic acid concentrate

Muriatic acid concentrate

We cannot stress enough here that suitable safety gear needs to be worn - old clothes, eye protection and acid-proof gloves are a must not an option!

Before you start, please make sure you read the manufacturers instructions on the Muriatic acid to find out what concentration should be used and also how to keep yourself safe. In most cases it will state to use a 10% water to acid solution but check first. Once you know, mix up a batch to those specifications.

Before adding the solution to the brick, wet the brick down with some clean, fresh water and then brush the solution on. Remember to use an acid proof brush or it will disolve!

As the acid solution starts to react with the mortar it will fizz. This is a sign that it is dissolving the mortar off of the brick. Leave it on for a few minutes and then rinse off, again using clean, fresh water. Be careful not to leave it on too long as it will start to dissolve the brick itself.

If after your first wash you still have mortar remaining you can also try using scraper or wire brush. Your first application should have weakened the mortar quite a bit and the scrubbing action should help to shift and further remains. Again be aware, the scrubbing action with flick the solution all over the place so ensure that you are fully protected.

On any real stubborn areas you can repeat the above process and even increase the acid concentration slightly in the solution. Don't get too carried away. As said, this is potent stuff and will ultimately damage the brick if too much is used.

Now that you know how to clean mortar from bricks the only thing left to do is get on with it! As you clean your bricks stack them neatly somewhere where they won't get knocked over or cause injury.

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