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White dusty spots on dark blue wall!!!!!!!!!

155K views 45 replies 21 participants last post by  chandler48 
#1 ·
Yeah recently I have noticed there are quite a few white dusty spots on my dark blue painted wall. This is something I have never seen before. This wall was painted dark blue over an existing painted wall about 6 years ago or so. I am hoping this is not mold. I was gonna try to spray 50 % water and 50 % bleach but I would think that would take the paint away from the wall. Any suggestions? Thanks.
 
#18 ·
Dusty spots

I actually had a mold person take a look and it was not mold. I sent a sample of the wall to a lab (per my County Health Dept) and they said it was not bacterial. They advised me to call my ins. co. which did. They looked and were stumped and actually called and hired HSA Engineers & Scientists to come over and investigate (which they paid for). The engineer drove 4 hours to get here; spent 3 hours at my home conducting extensive tests and determined the following: The white powder was consistent with 1 of 3 reasons: 1. excess pigment extenders in paint, 2. frosting, and 3. chalking. So...... I wiped it off all the walls and am waiting to see if it comes back.... so far so good; it's been since May 2011 and the walls look o.k. Good luck!
 
#29 · (Edited)
I'm gonna step out on a limb here, but I'm pretty certain this is not mold or mildew you're dealing with. And, for the record, it's impossible to say, with certainty, what the problem is just from these pictures. My personal guess, is one of a couple things. #1 is efflorescence. Efflorescence is often times seen on bare or painted masonry or cementitious surfaces (concrete, plaster, plasterboard, patching plaster, etc.). Efflorescence are soluble salts, brought to the surface via moisture or vapor transmission. This moisture may come from a damp wall or simply from the application of paint itself. Efflorescence may show up as a white stain or haze, or even as a thick, crystallized, powdery, chalky, dusty clump on the wall. Treating efflorescence is fairly simple (although if it is caused by moisture from a damp wall, that needs a different kind of attention). To begin, it may not be a bad idea to lightly scuff-sand affected area to break through paint film. To treat, mix a 50/50 solution of white vinegar and water and spray onto affected areas with a spritzer bottle - then allow to sit a few minutes. During this time, you may or may not see the white deposits effervescing - if so, wait a few minutes and repeat until the bubbling stops. Wipe affected area with a damp sponge, then rinse the area with clean water to neutralize..Allow to dry, then repaint.

#2 - May be paint frosting. If this is the case, the treatment may be a little more involved. Frosting is usually seen on tinted paint, often times in darker colors (only because the frosting isn't as visible on whites and lighter colors), and is the result of tinting bases containing calcium carbonate as an extender pigment (calcium carbonate is a common extender pigment used in most latex paints). The frosting may occur for a number of reasons - paint has too great a cc load relative to the amount of resin, atmospheric conditions at time of application, extreme temperature shifts during dry and/or curing time, humidity, etc. Frosting may be easily removed by just washing with clean water...and hopefully that'll be the extent of it. If it's more stubborn than that, do not paint over it thinking that'll take care of the problem - chances are, it'll bleed through an additional coat(s) of paint. In extreme cases (and I don't think we're dealing with that here), it could actually have an impact on adhesion of subsequent coats of paint applied. If the case is extreme and can't be simply washed off, it'd be a good idea to lightly scuff-sand the affected area, then prime with resinous, masonry type conditioner before applying finish paint.

Finally, if this were mold - don't panic - you already know the treatment for mold. Mold is not some sinister entity with evil intent. It is simply plant life - and it can be killed. The difficulty is the fact that what you see is not necessarily the extent of mildew. If mildew is in previous layers of paint, or underneath wall covering, and all you do is treat the surface - it may not be that successful. We live with, and breathe in, airborne mildew spores constantly - some people have allergic reactions to it, most don't. Mold, like all plant life, needs certain things to grow and colonize. Mold doesn't do as well in sunny or dry areas, so damp and dark areas should be monitored...Mold also needs a food source - which can be anything organic. Sometimes paint contributes to the food source - alkyd paints have an organic element that mold and mildew feed on - latex, specifically acrylics, not so much, but any paint tinted with organic colorants may provide food source...some organic cleaning compounds leave a residue that may be food source. When cleaning a surface affected by mildew, it's recommended that a bleach and water solution mixed into a detergent is usually appropriate. Stay with non-sudsing detergents such as Soilax or Dirtex Powder...Detergents like TSP, contains phosphates which is a fertilizer to plant life. Without adequate and proper rinsing to remove any detergent residue, TSP could actually create more of a problem.

I hope this info is more helpful than confusing, let us know what happens.
 
#3 · (Edited)
Here are a few pictures of what it looks like. It's all around the bedroom. I did wipe away an area and the white is gone however when the paint dries the paint appears lighter than the rest of the unaffected part of the wall. I think its mold. What is the best solution to remove it if it is mold?
 

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#6 · (Edited)
I kinda doubt that's mold. Except for the third picture, there are too many straight and curved lines in the "growth pattern" for it to appear natural. But, just cuz I ain't seen nuthin like that before, don't mean squat.

You said: "I did wipe away an area and the white is gone however when the paint dries the paint appears lighter than the rest of the unaffected part of the wall."

That very well could be because you simply didn't remove that whiteness completely.

Try this:

Using a Magic Eraser (No Name equivalent is fine) re-clean half of the area you cleaned with ordinary tap water and the other half with a bleach solution. (Check a 10% bleach solution in an inconspicuous area first and see if it harms your paint. It shouldn't. If it doesn't, try bleach straight of the jug on that inconspicuous area. Clean half the area previously cleaned with the Magic Eraser and ordinary tap water an the other half with the strongest concentration of bleach you've determined won't harm your paint.

Using bleach on one area and water on another will tell us whether or not it's alive cuz the bleach will kill any mold or mildew.

Using a Magic Eraser to clean the wall will tell us whether or not the whitish colour that returned after the first cleaning was just due to not getting all of the white stuff off the first time.

PS:
(Bleach shouldn't discolour your paint because the colour in it comes from tiny blue particles (called "pigments") that are suspended inside the paint film much like raisins in raisin bread. So, those blue particles are encased in plastic and don't actually come in contact with the bleach. But, confirm in an inconspicuous area just to be certain.)

When you cleaned the first time, what did you clean with? Soap, water, bleach, using a rag, sponge, brush, what?
 
#9 ·
It doesn't look like common traditional mold
But it could be that white, wispy, light and fluffy, "basement" mold we see around here
It's hard to say from here

You should not have to re-paint after using a mildecide, but that could depend on your paint
It wouldn't be an issue with a good paint, but cheaper paints may not hold up to it

Also, some cleaners such as TSP (**** and Span, some commercial surface and mildew cleaners, and the ever popular homemade Bleach/TSP/Water mix), and some tools (such as the Mr. Clean Magic Eraser) will slightly de-gloss most gloss finishes, and shouldn't be used on gloss painted surfaces unless re-painting (and in that case the de-glossing is a plus)
The product or tool will be labeled to that effect somewhere in the fine print
 
#10 ·
I wouldn't play around, to be sure i'd cut a layer of the paper and see if their is more mold issues between the coating and the Sheetrock and the paper and the rock. The more you mess with mold more the chance you can get sick. Once you mess with mold it starts releasing spores through out the house. Some painter belive to kill mold you need the 50 50 salution. After being schooled on mold I came to find that you cant kill mold. You would need cut the infected areas out if their more between the coatings.
 
#11 · (Edited)
Don't get me wrong, I'm not trying to be beligerant. We value experienced advice in here. The point of these forums is to help new homeowners figure out what's causing the problems they're having. But, when apparantly knowledgeable people all propose different reasons, about the only way the newbie has of determining which ones are plausible are by running them all through a "reality filter". That is, to carefully consider each alternative explanation for the problem and see whether or not it jives with the reality of the situation or not.

Specifically, I think the two statements you made that wouldn't pass through the reality filter are:

A) checking to see if there's mold between the paint and the sheetrock paper, and between the paper and the gypsum, because of the possibility that the white stuff came through the wall, and

B) not being able to kill mold.

If the original poster can clean that white discolouration off the blue paint so that there's no visible evidence of it anymore, and the previously affected area now looks just like the unaffected areas, wouldn't that prove that the white discolouration was deposited on the paint from outside rather than having come through the drywall, primer and paint to accumulate on the surface of the wall? That is, if the mold is white, and it passed through a layer of clear plastic with blue pigments inside it (the paint), wouldn't there still be some white "mold" particles still in that clear plastic film that would give it a whitish discoloration? That is, the white "molds" still in the paint film would act the same as white pigments to effectively whiten the colour of the blue paint, making it a "light blue" colour instead. If cleaning the paint film with bleach were to make those white "molds" clear, then wouldn't that bleach also affect the colour of the blue pigments inside the paint film, too? So, wouldn't the apparant lack of any discolouration of the paint film after cleaning prove that the mold didn't come through the paint film?

And, about killing mold...

When I clean a dirty wall with bleach, I get dirt accumulating on the damp rag or sponge I'm using, and the cleaning water I use gradually gets dirty. However, when I clean mildew off of a painted bathroom wall or ceiling, I don't see the sponge or rag turning dark, or any substantial change in colour of the bleach solution I'm using. If it's not possible to kill mold, then what I appear to be doing is only changing it's colour from black to clear. It seems to me that if I didn't kill the mold, I would soon see mold growing on the wet rag or sponge I used to do the cleaning with. I've cleaned mildew off many bathroom walls, and have never subsequently seen heavy mildew growth on the cleaning rag or sponge used to do the cleaning. In fact, I believe that if I used a cotton rag to do the cleaning, rinsed it out and put it in a plastic bag so that it wouldn't dry, mold wouldn't grow on it any sooner than a clean wet cotton rag under the same conditions. So, if the bleach on the rag didn't kill the mildew and it's spores, why doesn't the wet cotton cleaning rag become a growth media for mildew?
 
#12 · (Edited)
I just thought I would toss in that if it is mold, merely killing what is on there is the least of your problems. Mold is caused by excess moisture. If you don't stop the moisture, it will either: A) Grow back. or B) Even worse, grow somwhere where you can't see it, but it is still very bad for you.

Is this room damp at all? Judging from your pictures, this looks like a bonus room or other room with no attic overhead. Perhaps you have a roof leak, but it is soaking your insulation instead of dripping on your wallboard, which means no obvious water stains. Maybe a couple pokes with a cheap moisture meter would answer this question without having to destroy your wall.

SirWired
 
#13 ·
I had an instance where mold was coming through the paper to the surface and when I peeled a layer back :eek:

All I am saying is your telling a DIY to do all this stuff with it and your not sure if it is mold, alkaline or what ever. If it is mold you don't even know what degree it is. The more you mess with mold without taking care of the it. more the spores get around you living space. Which gives the pepole living in it more of a chance of getting sick. If you have mold on your substraight there is a chance that mold is in your wall. There was an area in the picture where it looked like the paint was blistering.

As far as killing mold, I,m talk about mold at it full degree. shower rooms that collect resadue just need to be maintained, and yes that can be taken care of a 50 50 salution. But the real deal you can not kill it, that just the way it is. I had it explain to me like this, if the dog craped on your floor and all you do is spray it with the smell good stuff and didnt clean it up. The air smells good but the crap is sill there. That is exactly what your doing when your one is trying to kill mold.
 
#14 ·
white spots on blue wall

I'm trying to reach Patsan... original author as I'm having the exact same problem on my wall and I'm wondering if they found the answer. A mold expert doesn't think mine is mold, and a paint expert is baffled and suggesetd getting a sample to the lab as he thinks there is definately some sort of reaction happening in the room.
Thank you
 
#15 ·
white on my walls also

I don't know if this is going to Patsan but I'm trying to find out if you ever found out what the white on your walls was from. I'm having the exact same problem.... mold guy doesn't think it's mold; paint guy has no clue other than to cut some wall out and take it to the lab.

Any info. you have is appreciated.

Thanks
 
#16 ·
Gail, are your spots on the outside walls only, meaning the walls that separate outside from inside, not the walls that separate rooms? Are your walls plaster or sheetrock? Is your house stone, brick, or other masonary type of finish? I've read this thread and I think it's mildew, but I'm trying to rule out any possible moisture transfer through the walls from outside.
 
#17 ·
Having the same problem! There are many round spots which are about 5 inches wide. They are almost in a patter. I am able to rub it off with my finger. Have it in two bedrooms. Calling a mold guy to check it out. I'm glad there are darker colors in the rooms, because if it is mold, I probably never would have noticed it.
 
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