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White stains & deposits in buildings - may not be mold: what is efflorescence, what causes this white powdery growth or stain on building surfaces, and what does efflorescence mean as an indicator of moisture problems in buildings? Here we illustrate and explain white or sometimes reddish brown bubbly surfaces on walls and white powdery or crystalline deposits left on walls, especially masonry walls, by moisture - efflorescence.
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How to Identify Efflorescence - Mineral Deposits (not mold) on Building Foundations and Masonry Walls or Chimneys
When investigating a building for a leak, water entry, or mold problem, you can save mold test costs by learning how to recognize Stuff that is Not Mold or is only Harmless Mold but may be mistaken for more serious contamination - save your money. Our photo at page top shows white fluffy crystals of mineral efflorescence near the bottom of a poured concrete foundation wall. Brown and other colors of efflorescence deposits are shown at Efflorescence & brown deposits.
Our photo at left shows white efflorescence on the outside of a masonry chimney - discussed at White/Light Stains on Chimneys.
To clean off efflorescence, see our advice at What steps should I do to remove efflorescence from my building?. Readers who need to cure or prevent efflorescence, mold or "mildew" in buildings should see STAIN DIAGNOSIS on BUILDING INTERIORS, and MOISTURE CONTROL in buildings as well as HUMIDITY LEVEL TARGET also VENTILATION in BUILDINGS and WATER ENTRY in buildings.
Because some clients have on occasion sent samples to our lab that really should not have been collected, much less looked-at, we provide this library of photographs of things that are "not mold" and don't need to be tested. These are substances that you can easily learn to recognize in buildings. Save your mold test money, and increase the accuracy of your mold contamination inspection or test for toxic or allergenic mold in buildings: review these items to learn recognize non-fungal materials or even possibly harmless cosmetic "black mold" often mistaken for "toxic fungal growth."
WARNING: Finding "not mold" material in a building does not mean that there is no mold or allergen problem.
Even relatively harmless house dust collected on a surface and sent to our lab as a mold screening test can contain a surprising amount of problematic mold spores if the building has a mold problem.
Mineral efflorescence is a sign of leaks into a building - leaks that might indeed produce a mold problem. But don't mix up efflorescence itself with mold.Save your money, don't bother testing mineral efflorescence nor the other stains we describe at HARMLESS INDOOR PARTICLES.
What about white "growth" or stuff on walls, particularly masonry walls? You may be looking at efflorescence - which is not mold.
What is the White Fluffy Stuff on Building Walls
Efflorescence or "mineral salts" is a whitish crystalline or powdery deposit on damp masonry walls, especially foundation walls which are located below ground level. Our photo (at left) shows a less serious case of white deposits on a concrete block foundation wall - white wall deposits at the mortar joints.
This usually-white fluffy material is efflorescence, a crystalline mineral salt left behind as moisture comes through the wall and evaporates into the building interior. Efflorescence is not mold, though it is an indicator of wet conditions that could contribute to a mold problem somewhere in the building.
Efflorescence can vary in its chemical composition and therefore its color too. Reported since 1877, these salts leach out of brick, concrete, concrete block, stucco, and in some cases even stone. The salts that you see have been left deposited on the surface as water evaporates.
Carson Dunlop Associates' sketch (left) illustrates how efflorescence is deposited on building interior walls.
Multiple kinds of mineral salts (chlorides, nitrates, vanadium, chromium and molybdenum) may be present in efflorescence material, depending on the masonry or stucco composition).
Vanadium salts, common in clay or brick products from some areas such as Southwestern U.S., may produce green efflorescence on white or buff burned clay surfaces. Other efflorescence salts leave white or gray deposits.
Various descriptions of this efflorescence, often seen on concrete, brick, or concrete block chimneys, walls or foundations (either indoors or outside) are provided in the list just below. Readers should also see the brown wall, ceiling, or chimney deposits are discussed further at Efflorescence & brown deposits.
Let's look at typical white efflorescence more closely.
By shining our light along the surface of this concrete block foundation wall we made the mineral salt efflorescence fluffy stuff show up clearly and we show how it grows "out" from the wall surface. (Photo, above left)
Looking at this material with a low power magnifying glass you can easily see that it is hairy and even crystalline (photo above right).
Here is a photo of efflorescence (mineral salt) which we collected from the wall (above) using clear adhesive tape, so you can see the appearance of mineral salts left behind by water leaking through a masonry block wall.
We used a low power stereoscopic microscope to see what this stuff looked like but it was not very informative so we decided to take a closer look using our Polam high-power light microscope.
You can see the crystalline structure of this substance in the long, translucent fibers. The black stuff is dirt from the wall surface.
Shown just above are two high-magnification microscopic photographs of efflorescence (mineral salts) which we took at 720x in our lab. This efflorescence sample was collected as "white powdery or cottony stuff on the foundation" by our client. It's easy to see that this is a mineral like substance, crystalline. It is not organic, not mold.
Below are two more microphotographs of larger particles of mineral efflorescence taken in our lab at 480x (4/19/10). The right-hand image of the same particle shown at left uses cross-polarized light to demonstrate a mineral quality of the substance. On the sample tape the material appeared as a white and light lemon-yellow powdery substance.
What Does it Mean to Find Efflorescence and Stains in a Building Interior?
You'll need to identify the sources of moisture or leaks and correct them, and depending on other building air quality complaints or health concerns it may be appropriate to inspect and screen the building for problem mold or other moisture or water-related problems.
Where you find efflorescence in a building indoors, you should look for problem mold, allergens, bacteria. Look on organic surfaces - wood, paper, painted surfaces, insulation, fabrics, carpets, carpet padding, or in settled dust and debris.
In our photograph (left) the client is pointing out that water has been entering this basement from the very top of the foundation wall (due to outside roof spillage and bad drainage) - we did not agree with the contractor who told her this was "rising damp" due to wet soils.
Question or Age of Efflorescence on a Building
I would like to know the typical length of time that is necessary for a crystal-like efflorescence thing in my photos to develop. I was told that it would take "years". I believe mine developed over a period of 3-6 months. Is that possible? Thank you again.
Background: I have spent nearly $4000 on a water intrusion situation that is no where near resolved. We live in the Dallas, TX metro area. Our property experienced a 3+ month long recurring city water main break beginning in Oct 2009.
During this time period I discovered mold growing all over household items and furniture. It was not until Feb. 1, 2010 that I looked in crawl space and discovered standing water on top of plastic vapor barrier. For the last three months I have consulted dozens of local experts, including engineers, foundation and drainage companies. My home owners policy rejected my claim as it was a city line that broke. The city insurance rejected my claim saying they have "governmental immunity".
Prior to the flooding event I have lived in this home for 13 years with no problems. It has only been since the city water main break that we have had these issues. The final repair to city line was completed in January. My crawls space has been so wet that no one will venture under there.
In April we installed an open face surface drain to catch roof and surface water to see if that would help. Even after this modification it now seems that with each subsequent rain event that more water is entering the crawl space. we are at my wits end and have about run out of funds to address this problem.
I have been in contact with my city council person and my goal is to try and get the city to help remediate this mess. I have a difficult task of "proving" to them that they are responsible for this. ... I believe the city water leak put so much pressure against my perimeter concrete foundation that what we are looking at is a form of efflorescence, rather than a fungus suggested by a city worker. Notice the weird staining patterns behind the crystal thing. Would you be willing to comment about what you see in these photographs? - S.M.
OPINION - is it Efflorescence?: It is pretty easy to distinguish between mold and efflorescence, as photos on this page show. Efflorescence is a crystalline mineral salt. It looks crystalline under magnification, even low magnification. The photo at left gives an idea of the typical size & scale of mineral effloresence formed on a building surface.
Mold is an organic growth and certainly does not look like crystals. See MOLD APPEARANCE - WHAT MOLD LOOKS LIKE. If necessary, a simple tape lift of surface material can let a laboratory confirm whether or not the substance you are seeing is mold or efflorescence
Watch out: the same conditions that produced efflorescence mean that there has been high moisture or even water in the building, just as you described above. So where efflorescence is found in a building, mold contamination may be present in the same or even other building areas (moisture travels upwards through a building from a wet basement or crawl area.) In addition to checking for mold contamination, it is very important to dry out the crawl space and keep it dry. See our guidance on crawl spaces at CRAWL SPACES.
The photographs shown above and at left (mineral effloresence around as single loose stone tile in a floor or wall) may have been of an old condition, but as we have found such stains on homes just a year or two old, clearly the rate of formation of mineral salt efflorescence on a surface depends on local conditions and a number of more technical variables. The lack of extensive rust or stains on other crawl surfaces argues that the water intrusion may be more recent than the age of the home.
Basically to find efflorescence on a building surface we need moisture wicking through masonry, then evaporating off of the surface to form effloresence.The rate of deposition of crystals probably depends on the level of soluble salts in the masonry through which water is moving, the level of other dissolved minerals in the water, other water chemistry factors, the extent and frequency of water source. All of that technical depth is beyond our expertise. But in general, we would not be surprised to see white stains on a masonry block wall in 6-months to a year if conditions are right.
Some moisture stains and efflorescence do have an older look, a sort of crust, that seems to form after a longer time of wet and dry cycling.
It's an interesting question - let's hear from some masonry chemists. CONTACT us if you have more information on efflorescence age.
Watch out: while we are sure that efflorescence can form on a masonry surface within months under the right conditions, don't mistake "old" efflorescence for "new". Some light efflorescence deposits can be quite old on a building wall.
But if you are sure that efflorescence satins on a surface did not have white efflorescence stains, yellow efflorescence stains, brown stains (as in our photo at left), tan efflorescence or stains at a particular time, and the material appeared more recently by your own observation, we agree that it is certainly accurate and reasonable that the correct assessment is that the efflorescence is new.
You may be able to sort out the age of efflorescence using some of the same thinking we use to sort out the age of mold: look for other evidence of the history of leaks or water entry such as other stains, or rot. See MOLD AGE - Old is the Mold?.
Painting over cracks where moisture has not fully evaporated or painting over a new stucco wall too soon and where the wall pH or alkalinity remains too high (over 11) can lead to both cosmetic problems as well as early wear or failure of the painted coating.
The application and curing procedure used for stucco, in turn affect the wall pH - it needs to be tested by the painter before the paint job begins.
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Frequently Asked Questions (FAQs)
Question: Bubbling wall surface, brown & white deposits, dusty: is this mold or efflorescence?
The bathroom is on the opposite side of that wall and you see on the photo that there are some piping there which I think are connected to the shower. When I scraped some of these bubbles I got some white powder like dust, however the concrete seemed to be dry with touch.
There are some bubbles and peeling in the bathroom (same wall) but concrete there seemed to be also dry with touch.
Do you think I have mold on my hand or just some stains which I can fix by scraping of the peeling painting and repaint?
Ps. The air humidity is normally 30-40% often nearer 30% mark.
Sincerely, S. - Iceland
Reply: Expect efflorescence on leaky masonry surfaces; expect mold on organic surfaces (wood, drywall, paper) when those surfaces have been wet
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem such as the moisture source that has caused the wall damage in your photograph. And certainly we can't absolutely identify building materials by email and photos, but that said, your photo looks to me like mineral efflorescence and bubbling paint on a masonry wall.
So if the wall in your photo is solid masonry such as painted solid concrete, concrete block or stucco or cement over a masonry wall, we're most likely looking at mineral salts left behind as moisture evaporates from the wall surface.
Why Effloresence Forms Paint Bubbles on a Painted Concrete Wall
The lifting power of the mineral crystals of efflorescence that form during moisture evaporation is quite strong, easily pushing paint off of the painted concrete wall to form the bubbly surface in your photo.
Take a closer look at that whitish or light yellow "powdery" material on the wall, using a magnifying glass and I expect you'll see that the material is crystalline - mineral efflorescence - not organic mold structures.
See the text in our Efflorescence article just above for more illustrations of mineral efflorescence Typically the problem comes from moisture leaking through masonry walls. I would not assume there is no mold in other areas of the the building however, particularly if you've had other leaks that wet more mold-friendly materials that support fungal growth such as wood, drywall, paper, carpeting.
More photos of brown and other colored deposits on masonry walls can be seen at Efflorescence & brown deposits.
Can Mold Even Grow on Masonry?
Most mold genera/species require organic material for food. In buildings that means mold-friendly materials include wood, drywall, paper, carpeting, paint, some plastics, cloth, and similar stuff. But indeed, we can on occasion see mold on a masonry surface, usually under one or both of the following conditions:
Relation of indoor humidity level and efflorescence formation on masonry walls
Finally, regarding your observation that "The air humidity is normally 30-40% often nearer 30% mark." - that's a pretty low indoor humidity level. But I'll bet that the location where you are measuring the relative humidity is not the surface of that bubbly stained wall, right? Typically when I see a masonry wall that looks like the one in your photo I find a leak or water source outside the wall, one that is sending moisture through the wall. The lower indoor humidity actually speeds the formation of efflorescent salts because the relatively dry indoor air helps speed moisture evaporation from the wall surface - leaving those salt crystals behind on the wall.
My advice: see if you can find and fix the moisture source that is causing the wall damage from effloresence in your photo.
Question: Is this white fluffy stuff efflorescence? and If So how should I clean and Paint it?
JO said: I'm not sure if I have Efflorescence or not! There is a small wall inside my Kitchen that has flaking off paint and the paint that is still attached looks like chalk dust. Is this just damp? If so, what paint shall i use? Thanks for any help and advice!
Reply: Cures for Efflorescence or "white mineral salt stains and deposits"
Jo, I can't tell from your description if you have efflorescence or just peeling paint. Take a look at the photos on the page above where we show just what efflorescence looks like.
The "cure" for efflorescence involves:
1. Find and fix the leak or moisture source that is causing the problem
2. Vacuum and clean off the surface thoroughly
3. You can re-paint using a moisture tolerant paint (latex) or on foundations a moisture resistant paint such as those made by Thoro (TM) [Thoroseal].
But if you don't find and fix the moisture source, peeling or chalking or efflorescence are likely to recur. The lifting power of mineral salts forming on a masonry surface is quite strong and has no trouble pushing off paint.
Question: How do I stop Efflorescence from Growing or Forming
Lorraine said: hi Jim, did you find a way to stop the effloresences? from Lorraine
Jim said: I have the same fibrous growth in certain places on my basement concrete floor. I at first thought it was mold and used bleach to wash the area, but to my surprise it was back in less then a week and just as tall, 1/4-3/8" high. After some research online today I see it is the salts or effloresences leaching up. Under the right conditions it only needs a week or less to become visible and be 1/4" or more high.
Reply: Find and fix the moisture source or efflorescence will continue to appear
Lorraine, cleaning off the efflorescence is easy, using just about any household cleaner, even a damp sponge or vacuuming and washing the surface, then letting it dry. You can also try applying a sealer suitable for the particular surface material. But if we don't find and fix the moisture source the efflorescence will return.
Question: I think I have Efflorescence growing out of a bathroom floor - but it's growing really fast. Will it stop once the concrete has dried?
Jenn in So.Cal. said: I have this, at least I think it is, growing out of my bathroom floor. But the stuff I have grew/grows REALLY FAST. We repaired a plumbing leak in said bathroom this past Saturday. After which, we decided to remove the carpet was not only completely soaked, but old and worn out. (frankly I've never quite understood the idea of putting carpet in a bathroom. Gross!!)
Anyway- This left us with the bare concrete slab as a floor. Before midnight that night, 50% of this bathroom "floor" was covered with fluffy white "waves" of fine crystalline growth around 1/2 - thick. I vacuumed it up yesterday afternoon, and this morning it was back to where it was the night before!
Before I found this great site, and reading thru the info you provide here, we worried it could be some mutant miracle grow mold, waiting to attack my asthmatic lungs or my husbands allergy prone sinuses. Or maybe just a result of many years of "love my carpet" type powders and/or carpet shampoo, or something else entirely. From what I've read so far, I think I've got mineral effloressence. If that is the case, will it stop once the concrete is dried out? I imagine we'll have to give it some time before laying tile. Which is fine, there's no rush. Are there any "prep" recommendations?? I thank you for your time. And for your wonderful and informative site. Very helpful indeed. I've already told a few friends about it! - Jenn in So Cal 7/19/2011
Jenn: Yes if you can dry out the area AND if you do not have an outside water source sending moisture up through the slab it may dry out enough that the efflorescence formation will stop or at least mostly stop; Efflorescence is a crystalline formation of mineral salts that can indeed appear rapidly on masonry surfaces when there is plenty of moisture present.
Question: I see white blotches where carpet squares were removed from the concrete floor. Is this a worry?
Half of my basement was completely finished 10 years ago and I have carpet squares with a rubberized backing over the concrete floor. I recently lifted up several squares and noticed small white blotches on many areas of the concrete floor. The carpet square backings are intact. Are the white blotches anything to worry about? They're not raised blotches -- they're pretty flush with the concrete. - Jim B.
Jim B: I can't know from so little info if the white blotches on the concrete floor under carpet squares are a real worry or not, but they do indeed sound like an indication of moisture in the basement; SInce the rubber-backed carpet squares are pretty moisture resistant, moisture may have been trapped on the concrete floor below, forming mineral efflorescence If you remove the carpet squares and clean the floor and keep the humidity in the area low (target 40%) and if there is not an outside moisture source, you should be OK.
Comment: how long does it take for effloresence to form in a building?
This efflorescence can take as little as days to form. I was at work scraping paint chips from an outside wall. Came back 4 days later and noticed this stuff all over the wall. So it does not take years by any means. - Joe
We agree, Joe. Effloresence can appear in days - we see this after a single-event flood that has wet a building; it is also a process that can continue for years, even decades. The extent of damage depends on the building materials involved and the amount of moisture transmitted to the building interior. Lots of moisture indoors also invites mold problems, rot & insects.
Question: After a basement flooding we see this white efflorescence stuff - could it be from remaining floodwaters?
in february we had a very very bad flood in our basement due to a broken water line, we cleared out the basement and removed the carpet. within a few days and major rain we noticed puddles forming by the exterior wall. we had the old clay weeping tile removed and replaced and window wells installed. since then we have noticed efflorescence forming on the floor in front of that same exterior wall. there is no dampness on the floor, (that i can feel) i have cleaned (vacuumed) this efflorescence and it returns within days. now that it has been dryer because of the summer weather the formation has slowed down. I would like to re-carpet the floor down there however i have to figure out what steps to take first to water proof this area. I have read many articles on the net but there is contradicting information. could the efflorescence be the remaining water from the flood and the pre-weeping tile? thanks - Teri. July 28, 2011
Teri, I've worked with efflorescence and building moisture and water entry problems since the 1970's. In all cases in my own experience as well as in what I've studied, you need the combination of moisture and a mineral-containing material like masonry, concrete, stone, cement, mortar, etc. to produce mineral-granule efflorescence Moisture wicks up through the masonry material from a water source, evaporates, and leaves dissolved salts behind on the material surface.
Efflorescence will pretty much stop appearing if you can dry out the area. Now I'd agree that following a cleanup it's possible for there to be some remaining moisture, say below a floor slab, or else an ongoing water problem that has not been cured. But if there were NO moisture, you'd not see efflorescence That's a sound conclusion.
thanks for your response dan, we just had a major rain and there is no evidence of water anywhere. we do have a sump pump in the basement as well, which does its job well. we also run a dehumidifier in the area. should i try to seal the floor with a concrete sealer before carpeting? and if so which one would you recommend? - Teri
Reply: A masonry sealer can slow down efflorescence formation
Teri if the floor surface is clean and dry a masonry sealer can help break the evaporation path that by capillary action pulls more moisture through masonry. There are two different approaches: silicone masonry treatments that mostly resist water entry into the masonry, and coatings such as portland cement based masonry sealer paints, or more extreme, epoxy paints.
No paint will withstand moisture pressure from beneath the paint surface for long, so paints don't absolutely stop moisture passage long term but they interrupt the evaporation-pull process.
But the masonry sealer paints I know about are not suitable for floors; you'd use an epoxy or other floor paint intended for concrete surfaces.
Frankly, all that said, if you've dried out the water source painting should not be necessary, but finally, in a basement, I would never put down wall to wall carpeting in any event. You're asking for an intermediate or long term mold and allergen problem. I prefer an epoxy painted finish floor, ceramic tile, or vinyl tile glued to the concrete floor surface. Over that if you want a few cleanable area rugs, that's fine. - Dan
Question: I bleached the efflorescence spots but it returned, Why?
I cleaned what seemed to be mineral efflorescence with bleach diluted in water, and the next day it appeared again in the same spot. Is it mineral efflorescence, then? Thanks. - Elena
Reply: Efflorescence is not a biological product; it reappears due to moisture or water leaks. Bleach won't "kill" mineral deposits nor stop their reformation
Elena, because mineral efflorescence is a mineral, not a biological product, cleaning with bleach is only of cosmetic use and may not really be necessary at all. You could use any household cleaner. But unless the moisture source is also found and stopped, the efflorescence will indeed return.
Just how fast efflorescence salts reappear (in your case the next day) depends on building variables such as the amount of water outside the wall, the rate of moisture movement through the wall, the mineral content of water when it reaches the inner wall surface, and the evaporation rate from that surface (in turn a function of indoor humidity). In other words, bleach won't stop efflorescence formation on a wall surface. - Dan
Question: Is the white fluffy stuff that appeared after Hurricane Irene efflorescence or mold?
After the water from hurricane Irene dried out of our basement, we have noticed some white fuzzy stuff that I believe is efflorescence. The floor where it is coming in is slightly pocked, as though the white stuff grew out of the floor. Does this sound like mold? - Slothburger
Reply: How to distinguish efflorescence from mold
Slothburger, there is white stuff that is efflorescence (crystalline mineral salts), and there is white stuff that is mold. If the white stuff looks crystalline under a magnifying glass, and if it's being produced on a masonry surface, it's probably efflorescence
At MOLD APPEARANCE - WHAT MOLD LOOKS LIKE you'll see a link for WHITE MOLD PHOTOS - take a look and you'll see the difference between what mold looks like and what efflorescence (this page above) looks like. - Dan
Question: We have efflorescence in a wall in our apartment. It will grow back within two or three days
We have efflorescence in a wall in our apartment. It will grow back within two or three days, even after being treated with a water-stop kind of "paint" -- we had a painter treat our wall and then he painted it, and after just a few days, the paint had already bubbled up again. It's going to be my one-year-old son's bedroom, and I really don't want bubbly paint in there... I don't know what to do to fix this... If it was just a basement, I wouldn't care. The wall appears to be dry. The plumber checked all the pipes. WHAT CAN WE DO???
I just commented about our apartment, and then read some more comments below, and it sounds like we have to find the source of moisture, but our plumber insisted that there was no leaking from the pipes in the wall (after he chipped away all the concrete around the pipes.) So I wonder how we can find the source of moisture in a concrete wall? -Teri
Indeed Teri, if there is no plumbing leak in a supply nor drain pipe (be double sure) then we have to look for other water sources such as roof spillage, roof leaks down the wall, or other outdoor water leak sources wetting that wall area.
Question: what is the best way to remove the white mineral salts stains on outside rendered and painted walls
Thanks - Marg
Reply: Look at our stucco paint failure information, clean, seal, and repaint + find and fix the leak
Marg you might search InspectAPedia for stucco paint failures for examples of white salts showing up in exterior paint on a masonry type wall surface.
Question: White crystallized material in the shower drain - could this be effloresence and is it a health risk to someone suffering from pseudomonas-related illness
My husband remodeled our bathroom. It has plenty of sunlight coming in. My problem is there is this "white crystallized material" that is collecting in the shower drain. My husband tends to think that because the shower is Travertine that it is run off from the stones, although he did put a sealer on them.
I have extreme lung problems and I am currently being treated for pseudomonas. I constantly worry about this stuff in the shower drain. I did not read anything on your website about efflorescence collecting in the drains only on buildings. Is it possible that this is what is in my drain and it's due to the regular moisture associated with shower water?
I appreciate any help you can give me. Thank you. Sincerely, H.G.
Reply: Effloresences in shower drain? Unlikely & in any case it's too small a particle reservoir to explain an indoor air quality health concern - but here are some things to watch out for
H.G., of course I'm sorry to read about your pseudomonas health worries.
If there is an effloresence problem on a building surface it is generally a salt crystalline material deposited on an above-ground above-water-level surface - because effloresence is a mineral salt left behind on a surface by the process of evaporation. It is very unlikely that the material in your shower darin falls under that definition - it's a wet area with little evaporation, and since the drain materials will be plastic or metal they won't be a source of mineral salts.
I agree that runoff or mineral deposits from tile could possibly collect in a drain, but I'm unsure what mechanism would leave that material specifically in a drain.
If you would be kind enough to send me some sharp photos of the drain and material in question as well as details about the tiles that you installed there I would be glad to comment further. If you like you can also send a physical sample of the material to our forensic lab where I may learn something further by direct examination. Use the CONTACT link found on any of our web pages to find an email and mailing address. [Note to other readers: please do not send us anything by mail without prior agreement by email. Unsolicited samples of any kind will have to be discarded. - Ed.]
Very small areas of just about anything are unlikely to themselves explain an indoor air quality problem
But more importantly, the total area and quantity of a deposit in a drain (surely no more than a 1-3 square inches) would not itself be a plausible source of high levels of a problematic indoor air particle.
Further investigation of your building for IAQ concerns
However building leaks, drain problems, or use of certain building materials in the construction of your home could be potential sources of irritating or otherwise problematic particles. A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with building moisture, or that might point to a material that is shedding or contributing to an indoor air quality problem.
While I argue that "tests" for indoor air quality alone, without taking a case history, building history, and without making a thorough expert building inspection would be unreliable, it might be appropriate to screen your home by some additional testing beyond just an inspection. Because a competent useful inspection and testing are costly, I do not recommend that step without some justification. See MOLD EXPERT, WHEN TO HIRE for help in deciding if such an inspection and testing are warranted.
As you probably know from your doctor and your reading, pseudomonas is a bacterium that is widespread in the human environment, and commonly found in both homes and hospitals. This bacterium lives in water. It does not spread through your home in air. As this bacterium can also be found in healthy people, more often people suffering from pseudomonas-related illness often have a compromised immune system.
In my OPINION, anyone suffering from a compromised immune system would want to take care to avoid living in an environment that might have high levels of contaminants or particles that are likely to exacerbate their health concerns. One group of such indoor contaminants often found in homes include various molds, some of which are often present in a home that has suffered leaks or moisture problems but that nevertheless can be hard to spot, such as some members of the Aspergillus and Penicillium families. A building screen for problem particles should thus include indoor mold contamination.
Check with your doctor
If you haven't already done so, you should ask your physician what sorts of environmental materials or exposures would be most likely to cause or exacerbate your own health problems. Those are materials for which we should first screen your home or other places where you spend most of your time.
Question: I cleaned off effloresence but it came back, what do I do now?
I cleaned what seemed to be mineral efflorescence with bleach diluted in water, and the next day it appeared again in the same spot. Is it mineral efflorescence, then?
Question: effloresence keeps growing back on our walls, effloresence seems to be spreading - how do we stop it?
We have efflorescence in a wall in our apartment. It will grow back within two or three days, even after being treated with a water-stop kind of "paint" -- we had a painter treat our wall and then he painted it, and after just a few days, the paint had already bubbled up again. It's going to be my one-year-old son's bedroom, and I really don't want bubbly paint in there... I don't know what to do to fix this... If it was just a basement, I wouldn't care. The wall appears to be dry. The plumber checked all the pipes. WHAT CAN WE DO??? - Teri 9/6/11
We expanded our living room 8 inches to meet the foundation blocks and new concrete was poured. Tile was placed ontop of the concrete and efflorescence began to form along the grout lines. It appears that our contractor did not do a vapor barrier under the newly poured concrete and this efflorescence is slowly spreading. Short of digging up the concrete (and the tile) is there anything we can do to remove & seal it from the top down? We live in Florida on a slab house, so we have a very wet rainy season, but even in the dry season we still are getting efflorescence in the tile (just not as fast). - Candy 9/28/11
How do you stop reoccuring effloresence on a concrete basement floor. I live near the water and keep two dehumidifiers running 24/7. The floor is not damp, but despite using muriatic acid and drylock powder several times, I still get reoccuring crystals. Some stopped, but there is still a great deal. - Kathy 9./29/11
Kathy et als:
Question: what might be causing effloresence on various surfaces?
We seem to have effloresence in our kitchen but don't know if we have a leak. It's an external wall (plastered some 5/6 years ago) that seems to have a pipe running up it (it gets hot if heating or hot water are on). This leaves the rest of the wall feeling damp and cold. Could it be the existence of the pipe in the wall that is causing the effloresence or is it more likely to be a leak? Had damp specialist out who seems to think the wall is not too damp and more likely to be condensation causing effloresence. So confused!! - Rachel 10/19/11
We are looking to buy a home and I see what seems to be efflorecence. It is in a small area of the basement. It is near the hose faucet. Also, we have had record rainfall in Maryland. Should I worry about this? Thank you in advance - Tim 11/1/11
i have recently been seeing the white patchs on my concrete walls in the basement. my neighbor had months of work done in their basement as they had been flooded. could whatever repairs they had done be redirected towards my property and that is why I am getting the efflorescence. My yard has always flooded in a big rain. - Diane 11/6/11
We recently saw a long line of red granular substance between the junction of the fire place brick wall and regular wall, was able to scrape it out, also saw it growing independently on the brick surface adjacent to the fire place, can't figure out what it is, can you please help. Thanks - Dipa P 5/23/12
Dipa: perhaps you can send us some sharp photos and we can make a more helpful guess - else we're flying blind except to suggest checking for water leaks, effloresence etc.
Question: how to clean off or remove effloresence
Hello, I read most of your info about cleaning but I am a contractor who has used white vineger in a spray bottle. Just spray on heavy and the white stuff desolves and runs off the wall. However it is not a permanent fix it will grow back in its natural time span as before. I have never had any good luck with any latex sealers or paint in this situation. My next test will be using epoxy paint or resin. - Cleaning 7/9/2012
Cleaning effloresence: thanks for your comment. I agree completely that vinegar, being acidic, works very well at dissolving mineral salts such as may be deposited on a masonry wall by moisture moving through and evaporating off of the surface of the wall.
Questions & Reader Comments: about effloresence in or on buildings
Wow this is by far the most informative and easily understood site on the subject of mould/effloresences, Thank you sooo much! - Erika 7/13/12
I have just built a new house with a concrete swimming pool, one side of the swimming pool is exposed on the outer wall, a couple of brown stains have appeared, as if the wall is seeping, the paint has also peeled, however when you touch the stain it seems to be dry, this has happened on 3 or 4 places along the outer pool wall which is approx 8 meters long, is this normall, pool is only 2 months old. - Tim Baldwin 8/24/12
Excellent site. Your photos are pretty good and I am fairly sure that I have effovescence 'growing' out of my concrete floor (This is after the area was jam packed with stuff for 4 months, no air circulation). My suggestion is to have pictures using more pixels so that one can zoom in on it to see a bit better the crystalline growth. - Jan Luthe 11/5/2012
Jan, thanks for the suggestion, I'll consider how we might follow it.
Question: Is the white stuff in this picture effloresence?
I would appreciate your opinion on whether the attached photo is most likely efforescence.
Thanks for the question & photo, J.L. Yes this looks like and most likely is indeed mineral effloresence, though I can't be completely certain from just the photo. The white crystalline filamentous material is reflective, shiny, and appears to be "grosing" up thorough a painted surface. There are some white molds that also produce white filamentous growth, but I wouldn't expect them to be shiny and reflective as is your photos (I've cropped and enlarged a central portion of your image - click to see an enlarged version of photos at InspectApedia).
Since effloresence is basically a crystalline salt left behind as moisture evaporates through and off of a surface, you can expect it to be shiny, reflective, and fragile, crushing to a fine powder or dust under a fingertip. As we explain in these articles, you can vacuum or wipe away the material, but unless you correct the underlying moisture source, just as with mold growth, it is likely to return rather soon.
Question: I've identified effloresence - it's not mold - the realtors were wrong; but how do I stop effloresence problems on a brick building?
Hi, After finding your very helpful site I've finally been able to determine that the white fluffy material and paint bubbling on several of our internal walls, is this efforvescence and not surface mould as the estate agents keep saying. However this confirmation in turn presents another problem. I have had to pull off and completely re-plaster and paint one of the walls already - when I did I found the walls were wet through behind the plaster, so I suspected rising damp or something anyway.
However now this stuff [effloresence] just keeps coming back. The house is rented and having told the estate agents (about what I thought was mold coming from the damp) I was told it was impossible since the house has had damp coursing.
This is an old house though and it was done after, with method of injecting some kind of sealant through drilled holes in the brickwork (i can see the drillmarks on the outside).
As I understand this isnt failsafe though and this efforvescence is coming up even on an internal wall (but mostly on the insides of the outer walls, but we do have a cellar under the house which gets damp - could this be the problem? I'm not sure how or what we can do to find or remedy the cause since I don't own the house and they will not listen, they just keep saying it's surface mould and to open the windows more! I know it's not because the walls were so wet behind the plaster. I'm sick of living in a damp house and cannot afford to move, fix the problem myself or keep plastering the walls just for it to keep coming back seemingly with a vengeance! :( I've wondered if using dehumidifiers could help at all? Not sure what else I can do. - Hazel Leigh 12/10/2012
Question: white fluffy moldy stuff growing in the shower
Does anyone know what this is? We are using the other shower since we are afraid that this could be something dangerous. As anyone had this experience?
Any insight is greatly appreciated. - M. O'B 3/8/2013
Your photo (included here) looks like effloresence - described in the article above. An interesting question is why the mineral salts are growing just around a single stone in your new bathroom shower floor. When we see just a single very limited effloresence formation such as in your photo I speculate that it's due to an installation anamoly, perhaps a contaminated stone or a poor seal around this individual stone.
If the stone didn't seal properly in a shower floor, when the shower is used water penetrates around the stone, wets the area below, and leaves mineral deposits as water evaporates back up through the same passages.
On the other hand if you begin to see more of this white crystalline "growth" forming on your floor I'd be looking for a leak or moisture problem below the floor. You will want to discuss that with your contractor. Normally we can't fix effloresence by sealing the in-room surface, but in this case, and if the water is coming from the shower above the floor, it's worth a try. Let the floor dry thoroughly then try a small amount of sealer recommended by the installer.
Question: reader gives example of rapid overnight growth rate of mineral effloresence
I was just researching to find the cause of some white powdery growth that I found on my basement floor after a flood. I came across your article on this page: http://inspectapedia.com/sickhouse/Effloresence.htm#H1 Part of the article talks about how long it takes for efflorescence to grow. You estimated that it could grow in as little as 6 months and you asked people to contact you if they had information regarding growth rates. Well, I have info!!!
I live in Aurora, CO and we just had some historic flooding. Prior to this week, my basement was fairly dry. In the past 4 days, my basement has flooded three times with fresh rainwater that seeped through concrete foundation walls and then pooled on my concrete floor. I was able to pump out and remove all visible water fully between each of the floods and I had fans going to dry the rooms out. I noticed the white stuff after the first flood and I sprayed it with Simple Green cleaner. After the next flood, it was back and slightly worse. After the 3rd flood it was back and much worse. This time I sprayed with Clorox Cleanup with Bleach.
It can grow OVERNIGHT to a height over 1/2 inch. Sorry I didn't measure before spraying it with bleach! Upon contact with any form of liquid it disappears, so I'm guessing it really isn't mold as I had previously feared. Whew! But I still don't know how to remove it. It looks scary and I don't want my tenants to think we have a mold infestation. I haven't tried scrubbing it yet... just spraying. It is snow white and grows up vertically in tiny strands. It looks like incredibly fine hair. If you rub it between your fingers, then it turns into white powder.
I will now return to your site to read and learn more about this odd substance. Thank you for your great info! G.L. Aurora CO 9/17/2013
Reply: effloresence is not a biological structure - no need to try to "kill" it with bleach; adding any moisture may increase effloresence formation
thank you for your note - indeed effloresence can appear quickly, and indeed I owe the topic some citation of sources on growth rates - for which your own experience and report are very helpful - I'll add that information to our published data. I did want to remind you immediately that using chlorine bleach is totally unnecessary when deailing with effloresence.
Because effloresence on masonry is a mineral crystal formation, it is not biological in nature: so "killing it" or "bleaching it" is both unnecessary and ineffective. In fact adding any evaporating liquid to the surface may simply increase the next rate of effloresence formation.
Spraying the identical site with water, or soapy water, or any household cleaner would be equally effective in removing the material, but I do NOT recommend this approach because we are adding moisture and thus starting a new cycle of evaporation from the surface - which in turn pulls more moisture through the wall from a presumably wet or moist exterior side. I'd prefer to HEPA vaccum or just wipe the surface.
If for cosmetic reasons we need to use a liquid cleaner, use as little as possible.
Ultimately the solution to effloresence (which is not always economically feasible) involves removing the water source from the other side of the surface on which effloresence is appearing or "growing" Without that step, we can slow, but not halt, effloresence formation by sealing the exposed or presumably interior masonry wall surface. By slowing evaporation from that surface we slow the pull of moisture through the wall, thus slowing the rate of effloresence re-growth.
For effloresence that appeared only in response to an indoor flood event such as a burst pipe, drying and cleaning the interior is the key step. Nonetheless effloresence may reappear on the previously affected wall for a time, even in this case, if the wall structure itself has absorbed much moisture.
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