What is that white stuff on the bricks? A white, powdery residue seen on masonry or brick surfaces, called efflorescence, is the result of moisture carrying metal salts through the concrete, grout or brick. When these dissolved salts are exposed to air, the water evaporates, they will leave the salt as a whitish deposit. The metal salts are typically sulfates or carbonates of sodium or potassium, and are not themselves dangerous. However, the presence of efflorescence may indicate a continuing moisture problem which could be dangerous to masonry and brickwork. Here are a few ways to prevents and get rid of efflorescence:
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Preventing Efflorescence

Since it is moisture which carries the metal salts through the masonry, elimination of water infiltration is the primary preventative. For housing foundations, proper drainage is critical. Roofs should catch rain and/or melting ice and send them away from the house foundation, with appropriately arranged gutters and drainage pipes. Building at the top of a hill can also force rain and ice melt to flow away from the foundation. Sealing the outside of the foundation with an adequate water shield (tar, plastic sheathing, or chemical sealants) will minimize moisture infiltration to the inner walls. For exterior landscaping masonry, a chemical sealant may be sufficient.

Note also, brickwork (or masonry) exposed to fountains or lawn watering systems, may also produce the white deposits typical of efflorescence, but these may also be due to the deposition of “hard water”, like lime deposits. Preventing water over spray, by blocking or redirecting the water spray pattern, or using a water softener system, can prevent these deposits.

Getting Rid of It

The whitish deposits should be physically removed by a soft brass wire brush first. Some deposits may be more stubborn and would require a stiffer steel brush, while others may be susceptible to a more gentle masonry brush or a simple bristle scrub brush. A final wetting down will carry away the smaller particles which may be caught in the masonry surface.

The remaining salt stains can be removed with a 50:50 mixture of TSP and water or a 50:50 mixture of vinegar and water. Brush this on lightly with the scrub brush and rinse immediately.

Commercial preparations, such as DryLock from UGL, Efflorescence Treatment from Aldon, or SureKlean #600 from ProSoCo may provide a stronger cleaning result. If these are used, be sure to follow the directions, and either rinse or do not rinse per the directions.

Prevention is the best policy, but assuring adequate drainage and avoiding water infiltration are key to preventing further efflorescence after treatment.