White fluffy effloresence on a concrete foundation (C) Daniel FriedmanRemove & Prevent Mineral Efflorescence
How to Clean off & Prevent Efflorescence, Salt Deposits, White, Brown, Red, Other

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How to clean off or remove efflorescence, stains, or "growths" on building surfaces:

Here we describe the remove & prevent mineral deposits, efflorescence, that forms white, red or brown stains on building interior or exterior masonry or stucco surfaces.

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>How to Remove & Prevent Efflorescence on Building Surfaces & Materials

Question: What steps should I take to remove efflorescence from my building?

Effloresence closeup (C) Daniel Friedman

What steps should I do to remove the efflorescence in my building? - Valerie Mercer

Reply: Ordinary Cleaning of surfaces followed by finding and fixing the moisture source are needed

Below we summarize procedures to remove efflorescence from both indoor and outdoor building surfaces.

How to Remove Efflorescence deposits on indoor surfaces

You can remove indoor mineral salt efflorescence from a surface by ordinary cleaning methods.

  1. Vacuum: If the surface is dry enough not to harm the equipment, I'd start by vacuuming the surface to get rid of most of the loose material.
  2. Wipe: Following vacuuming you can wipe the surface with a damp cloth or even use a spray household cleaner if you prefer and depending on the surface material. Any household cleaner, even a damp cloth wipe after vacuuming can be sufficient. Vinegar solution can also help dissolve white efflorescence stains
  3. Dry: as we repeat ad-nauseum, if you cannot also find and fix the moisture source then the efflorescence will return.
  4. Patience - Repeat: you will almost always find that efflorescence will return and be cleaned off of indoor surfaces, especially floors and masonry walls that are below grade, several times before the problem goes quiet, since it can take time for moisture in masonry walls or earth against masonry walls to dry out. If the efflorescence returns as ugly as ever you may not have found the water or moisture source.

Dehumidification for efflorescence control? You might think that indoors you could just run a dehumidifier but in my opinion that won't fix an efflorescence problem since almost always efflorescence on masonry surfaces indoors is caused by outside moisture that is penetrating the building.

Masonry sealer paints for efflorescence control? Painting the interior side of an exposed masonry foundation wall with a masonry sealer paint will not fix an actual basement wall leak and in such cases the paint job will not be long lasting protection against efflorescence either. However, painting the interior surface of the foundation wall with an appropriate sealer paint will slow down the passage of moisture through the wall and thus slow the formation of mineral salts in the future.

Incidentally, in our white efflorescence photo (above left), the concrete wall had been painted, but not with a masonry sealer paint. We can make that guess because masonry sealer paints typically appear thicker and more granular on the wall due to their content of portland cement and sometimes sand for added body and waterproofing.

How does the sealer paint work to help against basement moisture? A significant factor in the movement of moisture (as opposed to an outright water leak) through a foundation wall is the combination of capillary action that moves water molecules through a substance and evaporation from the indoor wall surface that acts as a molecular pump to send that moisture into the building air. By sealing the interior surface of the foundation wall we are significantly slowing the capillary movement of water thorough the wall by interfering with its ability to reach and evaporate into room air.

How to Remove Efflorescence deposits on outdoor surfaces

Effloresence white stains on a chimney (C) Daniel FriedmanThe stains on this brick chimney are introduced at CHIMNEY STAINS & LEAKS. On an outdoor masonry surface you can use soap and water or just plain water and a spray hose or if the surface can tolerate it, a power washer to remove efflorescence

  1. Brush: gentle brushing with a soft bristle brush can knock off heavy efflorescence and make additional cleaning easier.
  2. Wash: gentle spraying of the masonry surface can remove additional efflorescence and staining, though adding water and really soaking the wall will probably also encourage the formation of the next generation of mineral salts that form on the masonry or stucco surface. For this reason I prefer to keep use of liquids to a minimum. If the exterior surface is un-painted masonry I might try a little vinegar solution spray to help dissolve efflorescence and to slow its reappearance.

    Watch out: take care not to blow water into the building nor damage exterior surfaces when using a power washer / sprayer. For example, many antique brick walls use bricks whose exterior skin is hard from the firing procedure. But if your power washer (or for painters, your sand blaster) removes that hard coating from the exterior brick, the exposed soft brick will weather, leak, and deteriorate rapidly. You'll have ruined the wall.
  3. Dry: find and fix the moisture source.
  4. Patience - Repeat: you will almost always find that efflorescence will return and be cleaned off several times before the problem goes quiet, since it can take time for moisture in masonry walls or earth against masonry walls to dry out.

Find and fix the outside moisture source of leaks into a building interior or into a building exterior masonry component

Watch out: when the surface is dry and looks better or even perfect, you will nevertheless see a return of the efflorescence unless you find and fix the exterior leak source.

Outside, for example when you see efflorescence on portions of a brick chimney, I'd look at the chimney crown and roof flashings to be sure we're not allowing water to penetrate the chimney interior. After cleaning an exterior masonry surface we sometimes will treat the surface with a silicone or similar waterproofing compound such as products sold by Thompson's Water Seal™. (To remain effective, such coatings need to be renewed frequently.)

Details about tracking down and fixing sources of leaks into buildings and thus about preventing efflorescence deposits (as well as mold and "mildew" in buildings) are found

Question: efflorescence on our walls - seems to be drying out, should I be concerned

Hi, will 9 years of no eaves troughs cause Efflorescence? When we bought our home it had no eaves and we installed them immediately. Now 6 years later there are white marks suddenly appearing 6 inches above the floor on the garage concrete. I am fairly positive this area has been drying out visibly, should we be concerned? - Laura 5/13/2012

Reply: Maybe

Small amounts of efflorescence that dry out and are not signs of pumping significant moisture into a building, if they are on a solid masonry wall, are more of a cosmetic than a functional worry.

But large areas, constantly growing mineral crystals, or stains that suggest that significant amounts of moisture are being pumped into a building can be signs of or contributions to related problems with indoor mold contamination. For example, efflorescence on the plaster surface of a wood framed, insulated wall, means there is quite likely problematic moisture inside the wall, inviting mold, moldy insulation, wood rot, or insect damage. In such cases, further investigation of the cause, extent, and measures to cure the moisture source would be in order.

Also see


(Mar 31, 2013) Linda said:

The article was informative, but how do I solve the effloressence problem on my concrete basement floor?



You have to find and fix or correct the source of moisture

Question: what is causing these white efflorescence stains on my exterior wall and how do I get rid of it?

Effloresence white fuzz on exterior stucco wall (C) MJ Effloresence white fuzz on exterior stucco wall (C) MJ

Please see attached for pictures trying to figure out what the issue can be on the bottom?
Everyone 3 landscapers are telling me there is not a water issue?
The walls are less than 6 months brand new. - Anonymous by private email 2016/11/11


I cannot, of course, diagnose the cause of these water stains and efflorescence at the bottom of the wall in your photos as I can't see the rest of the building.

From the photos it looks as if the exterior wall is stucco coated-concrete or concrete block or it's an EIFS synthetic stucco wall. See EFFLORESCENCE SALTS & WHITE DEPOSITS for more about white efflorescence stains or blooms on stucco building exteriors.

But IF there is no water and no moisture staining indoors at a foundation wall of a basement or crawl area on the other side of the walls you show, and IF the patio drains away from the building, not towards it, and IF the roof gutters and downspouts are working so that we are sure you're not spilling roof runoff or surface runoff against the building wall, THEN the water stains are probably due to a smaller amount of water, say from rainfall or wet soils at the patio-wall juncture and should dry out in dry weather.

If that's a garden hose hookup I see in one of your photos, that hose bibb and hose could be a source of extra water in this area.

It's common for the bottom of a new stucco wall to be the last to dry-out as it is in contact with soil. And damp or wet soil extends that time, increasing the chance of formation of white efflorescence mineral salt deposits along the wall bottom.

Any steps you can take to be sure that there is no roof drainage splashing onto this wall and that the patio slopes away from the wall will improve the situation.

Other readers who see a white bloom on stucco after installation or painting of that material should see PAINT on STUCCO, FAILURES for details of paint failure diagnosis on stucco surfaces.

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