Brick Efflorescence: What It is and How to Beat It

Brick efflorescence is that 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.

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:

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.

Prevent water passing through the wall: Even if your wall contains water soluble salts, those salts can't cause efflorescence unless 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.

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.

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 leave!