White powder on Bedroom walls

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Old 10-06-16, 09:45 AM
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White powder on Bedroom walls

Hello, I hope I can get some info on my problem ..... thank you in advance. When I moved into my house the bedroom walls were light green (I think flat paint was used). 8 years later we decided to pint the walls a light beige. My brother did the job and told me to get BM paint. Don't remember what kind it was but it wasn't flat. There is a bit of a sheen to it so it may be an eggshell. As he was painting he said the paint (no priming) wasn't sticking to the walls.He wiped some of the walls with water and waitied till they dried but he still had difficulty with the paint adhering to the walls. I told him to just do the best he could. The walls took 2 good coats and it looked ok. Now it's 6 years later and I begin noticing white powder on areas where the walls would have been spackled. At seams, around vents and where screws were. Then I begin noticing it on areas where there is nothing. This is only happening in this room on interior walls. There is no plumbing and it is not mold. 2 walls are against the outside of house and 2 are on the inside. One area was above a baseboard molding so I wiped it with plain water and it has stayed clean. I tried vacuuming the walls with the brush attachment and it did nothing.Then I decided to wash the whole room with a mop ..... bad idea. It seems to have smeared the powder in the entire room and I didn't realize how much powder there was until I disturbed it. This is the only room where this has happened. Over the years we have painted every room and have not come across this problem. Now the whole room is a smeared, white mess.I had a few contractors who were doing different jobs look at it and they have never seen it before. I am assuming this is spackle dust? How do I fix it? Washing the entire room seems a monumental task for my hubby ad I as we are both disabled. In the pics you can see the worst parts but there is also smears that are not as easy to see. I'm assuming I need to prime the walls before painting again?
 
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Old 10-06-16, 10:46 AM
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My guess is that this is somehow related to the furnace filter not being changed often enough... or in some way it is just a lot of dust being deposited on the walls by the hvac. Yes, could be leftover drywall dust in the ducts being recirculated.

Washing is the solution, vinegar water with just a bit of soap would be best. You will want to have 2 buckets... one with clean rinse water. If the rinse water gets dirty, change it.

You don't need to prime walls unless it is either unpainted drywall or you have a stain that paint won't cover. You don't want to prime over a wall that needs to be washed.
 
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Old 10-06-16, 11:08 AM
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Did the last paint job adhere well to the underlying paint?
I agree that you need to clean the walls before proceeding further.
 
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Old 10-06-16, 11:30 AM
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No the paint wasn't adhearing well. My brother/painter used vinegar n water which didn't help. Then bleach n water which also didn't help.
 
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Old 10-06-16, 11:33 AM
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No, not furnace. Duct work has been regularly cleaned and furnace filters are always replaced. It is only in this room.
 
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Old 10-06-16, 11:35 AM
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Sounds like there was some type of contaminate under the last coat of paint. I'd sand the walls with 80 grit and see how much comes off. You might want to skim coat the walls after sanding in order to make them smooth again.
 
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Old 10-06-16, 12:06 PM
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I just found this reply in another post from 2011 from someone called "ric knows paint" in a DIY chatroom..............

OK...process of elimination may be the best thing to determine what's going on here. To begin, how do you know it's not mold? Have you tried to wash it down with a mild bleach or peroxide solution? If so, did the white powder return - if that's the case, you're right, it's probably not mold.

As long as we're experimenting, try washing with a 50/50 vinegar wash on an area and see what happens. If that takes care of the problem, and the chalky appearance doesn't return, you may have an efflorescence problem (especially if these are plaster walls) and a thorough acid wash (mild acid) should take care of it...A vinegar wash should also take care of laitance and saponification. If any of these are the case, a detergent wash may actually aggravate the problem more. But if it were efflorescence, laitance or saponification, I think there'd be an easily identified caustic "burn" to the paint in the form of blisters, loss of adhesion or discoloration beyond the white haze.

So, if bleach, peroxide or vinegar doesn't do the trick, you've probably got a condition called "hazing" or "frosting" - which is actually caused by one of the components of the paint itself. Frosting is a condition where un-bound, or loosely bound, calcium carbonate "floats" to the surface of a paint film caused by a number of possible factors. It mostly appears on medium to dark tone paints (it happens on lighter color paints also, it's just not very noticeable) - and can be pretty stubborn to remove.

Untreated, frosting can also "bleed" through subsequent coats of paint or primer and just keep re-depositing itself on the surface. Severe cases can actually affect adhesion of the paint as well. While this is not a definitive test, a common or tell-tale sign is if it kind of disappears when washed with just clean, plain water - only to reappear in a few minutes or hours.

The reason for this is kinda simple. Calcium carbonate, a commonly used pigment in paint, is actually baking soda. If you mix a spoonful of baking soda into a glass of water, you'll notice the baking soda turns clear upon stirring. If the water is allowed to evaporate, there remains a white, opaque crust in the bottom of the glass which, of course, is the baking soda. Kinda like a wet t-shirt - transparent when wet, opaque when dry...

IF this is the case, the treatment is not difficult but it's going to require priming and repainting...but not priming with a typical, white primer. You're going to want to use a clear, resinous product such as Zinsser Gardz or an acrylic masonry sealer such as Seal Krete (both are found at most paint stores - not necessarily the big boxes). Usually once primed with either of these two products, you're safe to go with your choice of finish paints.

Finally (and, again, IF this is the case), don't be real quick to blame the last coat of paint applied. This very possibly was caused by any of the previous applications of paint or primer over the years.

I hope this info is helpful - good luck.
 
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