Time is often the best cure for efflorescence. On a slab, such as a basement or garage floor, or on patio blocks, for example, wear and foot traffic will eventually remove the discoloration. New building bloom on a brick or stucco wall will usually not reappear if washed away by rain or brushed off by the homeowner. Especially on naturally colored concrete, where the white deposits hardly show, just waiting for it to wear off might be your best bet. If you're itching to take some sort of action, though, there are a few options:
- Simple washing can sometimes remove efflorescence. Scrub with a stiff brush and mild detergent or plain water. Efflorescence is most soluble when it first appears, so sooner is better than later if you want to try this approach. Just wetting efflorescence can make the film seem to go away (it actually becomes transparent), but you'll need to apply some elbow grease to do a thorough job. Always be sure to rinse thoroughly. If you leave dissolved salts on the surface, they'll return as new efflorescence.
- Power washing also can be effective in removing surface deposits. Keep the pressure as low as you can to do the job. A spray that's too intense may actually open pores in concrete or brick and encourage further efflorescence.
- Sand blasting is effective, but should be used with care. The abrasion may damage surfaces, making bricks and mortar more porous. If you choose to try sand blasting, seal the surface you're working on after you're done.
- Chemical cleaning might be needed for some cases of efflorescence. However, always soak the surface with water before using chemicals in order to keep the cleaner from penetrating into the stone and further opening pores that encourage efflorescence. If you choose this strategy, you can follow the directions of one of the proprietary cleaners on the market, or you can use diluted muriatic acid, citric acid or vinegar. Make sure you wear gloves and goggles when handling acids or cleaners. After cleaning, neutralize the acid with a baking soda solution and finish by washing the surface thoroughly with water [source: Nasvik]. Acid cleaning may discolor stained concrete, so test it on a small section first.
A general rule for cleaning efflorescence is to try gentle methods first before moving on to harsher techniques [source: Koski]. But really, the best approach to dealing with efflorescence is to keep it from forming in the first place. Find out how to do that on the next page.