White chalk bleeding thru painted concrete

[PAGUY]

Anybody got any ideas how I can stop this white chalk bleeding thru the painted wall and step in my basement? I tried wire brushing and painting with a primer/sealer and then final finish coat of paint but in time it just bleed thru again.

[cmuncy]

What type/brand primer and sealer are you using and is it a poured concrete wall or cinder block wall?

[PILOON]

If not mistaken that white is a salt and as such should be alkaline which suggests that it needs an acid wash to neutralize.

Again I believe that generally one wants to acid etch concrete prior to applying paints.

Good luck!

[ray66v]

That is called efflorvesence, it is mineral deposits that result from moisture coming through the wall. It is fairly easy to remove it, (a wire brush is usually effective), and the wall needs to be painted with a water proofing paint. Make sure the paint you use is specifically made for below grade applications. These paints contain Portland cement and will seal the wall to stop the moisture penetration. I have recently used a new one that was a low odor oil based product {Zinsser Watertite}. This product was unusual because it left a smooth surface rather than the sandy surface other waterproofing paints usually leave.
However, there could be an underlying cause that needs to be addressed: The exterior walls may need to be water proofed, and proper drainage maintained, (not all that hard to do but can be a lot of work), to completely eliminate the problem. The problem is more common with cinder block walls than concrete. because they are more porous.

[PAGUY]

Thanks guys for replying. The wall is cinderblock and the step is poured concrete. I tried Kilz primer after wire brushing but it returned. Will try again with information received.

I knew this would be the place to get answers. Thanks again.

[Egon]

Are the blocks made from sulfate resistant concrete??

[PAGUY]

House was built in the 1940's. Block was painted with concrete inside and out. Only one wall on westside of house has the problem. The concrete step was poured concrete in basement of addition add-on in 1990. The addition was concrete block and plastic drainage pipe was buried on the outside wall which was covered with black foundation sealer.

No water leaks at either sites just chalk.

[MrJimi]

You mention chalk? I am thinking about blackboard chalk. What exactly do you have?
It sounds like you have something else other blackboard chalk
Jim

[PAGUY]

It is a white flake that looks like chalk. You can vacuum it up and it will reappear in time. Would like to seal it for good for appearence sake.

[ray66v]

Kilz is NOT for below grade applications make sure you use a product made for below grade like I mentioned previously.
The problem now is the wrong product is on there and your going to have to remove the problem areas as they pop up and treat them with the right product.
There is no good way top remove all the existing material and putting the right product directly over the existing will NOT work.