Brick Efflorescence: What it is and How to Beat it

Brick Efflorescence: What it is and How to Beat it

You love your bricks until white deposits seem to appear on them from nowhere. Efflorescence seeps out from inside your bricks or mortar to form an ugly film that can be tough to remove.

Read on to learn what brick efflorescence is and what you can do to prevent it before it strikes, clean it if you’ve got it, and keep it away.

What is Brick Efflorescence?

bricks with efflorescence angle_c_r_o

Brick efflorescence is a powdery white residue that accumulates on bricks, mortar, and grout, usually during the first year after construction. Efflorescence is made up of water-soluble salts that are present either in the bricks themselves or in the mortar before construction, and which are washed out to the surface by water passing through the porous material.

As water passes through the bricks, it dissolves the salts and carries the dissolved salts to the surface of the brick, and leaves the salts behind as the water itself evaporates. Efflorescence doesn’t damage your bricks, but it definitely harms their appearance with its powdery, crystalline mess.

How to Prevent Brick Efflorescence

bricks with efflorescence straight_c_r_o

In order for brick efflorescence to become a problem, your brick wall has to meet three conditions:

First, your bricks or mortar have to contain water-soluble salts such as sodium sulfates (Na3SO4) or potassium sulfates (K2SO4).

Second, water has to be able to get inside of the bricks and dissolve the salts.

And third, the water has to have a pathway to reach the surface of the bricks and deposit the dissolved salts.

Eliminate any of these three conditions, and you will prevent brick efflorescence from ever starting. Taking steps against two of these conditions—or even all three—is even better, just in case one of your preventive measures doesn’t work out as well as you’d hoped it would.

Here are some ways to stop brick efflorescence before it starts:

  1. Prevent salts in the wall: If the wall hasn’t been constructed yet, choose materials that are less likely to contain water-soluble salts. Most modern clay-fired bricks have additives such as barium carbonate that make salts insoluble, so the bricks themselves aren’t usually the source of the problem. Mortar and grout cement can be a big source of efflorescence salts, so choosing low-alkali Portland cement for mortar and grout can help eliminate efflorescence problems from that part of the wall. The sand you use for the mortar and grout can also be contaminated with salts that can cause efflorescence, so it’s important to use clean, washed sand. It’s also important to use potable, clean, salt-free water during the entire construction process to prevent contamination. You can also use mechanical vibration to consolidate the grout and make the pores smaller, so less water can travel through, and there are chemical additives that you can buy to mix in with the grout to prevent efflorescence.
  2. Prevent water from passing through the wall: Even if your wall contains water-soluble salts, those salts can’t cause efflorescence unless the water gets to them and dissolves them first. You can minimize the amount of water than enters your wall by using copings, flashings, and eaves, and constructing tight mortar joints. Also, keep lawn sprinklers away from your brick wall.
  3. Prevent the salts from being deposited on the wall’s surface: Even if your wall contains water-soluble salts, and water gets inside of the wall and dissolves them, your wall still won’t develop efflorescence unless the dissolved salts can be deposited on the wall’s surface. Some companies make special sealants that are made to prevent efflorescence. Keep in mind that these sealants are different from a regular silicone sealant, which just sits on the surface of the wall. If you use a surface sealant and have a potential for efflorescence, the dissolved salts can rise to the surface of the bricks and visibly build up underneath the sealant, making a huge mess and possibly even causing enough surface strain on the bricks to make them start to crumble. Efflorescence sealants are made to penetrate into the pores of the bricks and prevent the salts from emerging, so choose with care.
Brick Efflorescence Removal

If you’re already dealing with those ugly white crystals building up on your brick walls, the big question is how to get rid of them without doing any harm to the bricks, and hopefully keep them from coming back.

Sandblasting is one method for removing efflorescence. Sandblasting will remove the salt crystals from your wall, but this is a very rough and abrasive method of cleaning that damages your wall’s tight mortar joints, making them more porous, and also blasts away parts of your wall’s surface and makes it more porous.

Making your wall more porous allows more water in, where it can readily dissolve the salts that are there. Repeated sandblasting adds a lot of wear and tear to your wall.

Another option for cleaning brick efflorescence is using muriatic acid. The Masonry Institute of America recommends mixing 1 part muriatic acid with 12 parts water, thoroughly pre-soaking the wall beforehand and thoroughly flushing the wall afterward to remove all of the acid, and using several mild applications rather than too-strong one.

Be prepared, though: all of that water just might wash more efflorescence to the surface if your wall has additional undissolved salts inside.

Several companies also make specialized cleaners for brick efflorescence. They come with specific instructions for use. Most are acid-based and use a pre-soak and rinse procedure.

The U.S. General Services Administration offers these chemical-free but work-intensive instructions for removing efflorescence from your wall with a brush.

How to Keep Brick Efflorescence Away

Once you’ve removed the efflorescence from your wall, you want to keep the unsightly white residue from creeping back out of the pores in your bricks and starting the whole process over again.

The way to stop efflorescence from coming back is to interfere with its three necessary conditions: water soluble salts in the wall; a path for water to get into the wall and dissolve those salts; and a path for that water to reach the wall’s surface and deposit the dissolved salts.

If your wall started out with only a small amount of water-soluble salts within it, the efflorescence might stay away on its own after one cleaning, or only lightly return. But if you wall has a high salt content, the efflorescence could develop again and again.

The first thing to do is to take steps to keep water off of the wall as much as possible and see what happens. Consider a penetrating sealant that is specifically made to prevent efflorescence.

Again, don’t use a typical silicone sealant that sits on the surface of the bricks, because you risk salts rising to the surface and building up behind the sealant. If your bricks have a high salt content and efflorescence is a chronic problem, the U.S. General Services Administration offers two environmentally-safe methods for removing water-soluble salts from your brick wall.

They both require patience and your wall won’t look very pretty in the meantime, but dealing with efflorescence’s root cause is definitely worth it. If you decide to try this, you would need to do it before you seal your wall.

Removing as much of the water-soluble salts as possible from your wall, keeping water out of your wall, and sealing your wall to keep water from passing through the bricks and carrying dissolved salts to the surface, will prevent the ugly white haze of efflorescence from marring your wall’s appearance again.

Does Wet & Forget Outdoor Remove Brick Efflorescence?

brick cleaner

Wet & Forget Outdoor is specially formulated to eliminate outdoor growths, so it’s not designed for use on efflorescence.

Wet & Forget Outdoor does wipe out many of your bricks’ biggest enemies, such as moss, which can cause pitting and crumbling; lichen, which can cause surface etching; black algae, green algae, and mold & mildew.

Wet & Forget Outdoor’s gentle formula is safe to use on any type of bricks, mortar, and grout, and there’s no elbow grease needed—just spray and forget about it!

Click here to learn about cleaning your bricks the easy way with Wet & Forget Outdoor.

Photos courtesy of Pete Birkinshaw.

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White deposits can build up on brick and give it an unattractive appearance. Learn what causes brick efflorescence and how to remove it with this easy method!