Just completed an addition to a brick home. The new brick would match a lot better if I could get the old brick clean. The landscape sprinklers have been spraying onto the brick for years. We have that problem corrected now. The water source for the irrigation is city water supply. There are white scale type deposits on the surface of the brick (wood molded brick). I have tried brick staining and also cleaning with muriatic acid and a stiff nylon bristeled brush. Neither has worked.
Anybody have a solution to this dilemna? Thanks for your help.
Chris Calhoun
Blackstone Builders
Replies
There is a product called white scum remover.
It's for calcium deposits, but I would suggest
testing a small area first, may take a couple
applications. The one I've used is made
by Prosoco. There may be others. Muriatic is more of a
general cleaner, this stuff helps to soften the deposits
to make it easier to remove (don't know the science behind it...)
Mclaren
the while scale is salt leaking out of the mortar,
.
Know BOB, Know Peace
Normally this is efflorescence of mineral salts coming from the mortar and leacjing out from all the water running through it.
Typically a ten percent muriatic wash and scub will take care of it. What mix did you use? It mught be that you need to try upping it closer to 25%, but be very carefull, wet the brick first, try a small area to test. Wear rubber gloves and goggles.
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I tried a fairly strong mixture of muriatic and water, wet the brick first, applied acid mix and let sit. Then scrubbed with brush and rinsed with clean water. I did this several times and no progress. I have been tempted to use a wire brush but am fearful that it will damage the brick.
Chris Calhoun
Blackstone Builders
I have done a lot of work with water formed scales over the years, and it sounds to me like you have a sulfate-based scale, most probably magnesium or calcium sulfate. Whether or not it is calcium or magnesium sulfate is immaterial, it is the sulfate that is important. If you had been lucky, it could have been calcium or magnesium carbonate, but the muriatic acid, which by the way is nothing more than dilute hydrochloric acid, would have dissolved it very quickly. The fact that it did not, indicates a sulfate scale. Sulfate scale is a problem wherever it forms and is very difficult to dissolve without dissolving whatever it is attached to as well.
I am at this moment trying to remove sulfate scale from some very old pottery by soaking it in supersaturated disodium carbonate. This process works by slowly replacing the sulfate with carbonate, which can then be dissolved easily with an acid - like muriatic acid. But, the problem is that it is a very slow process and it can take days, if not weeks (in my case years), to replace the sulfate with the carbonate. Another method would be to use a chemical such as disodium EDTA. This is widely used in industry, but it is quite expensive and should be handled with care. You could also try some of the proprietary scale removing solutions, but beware that 99% of these are in fact useless on sulfate scale.
Sorry to be the bearer of bad news, but sulfate scale is a problem in a great many places.
Call the City water supplier and ask them what is in their water. They are required to have the analysis done on a regular basis, and it is public information. While you have their water quality guy on the phone, ask them what to try getting the deposit off with.
A lot of them have degrees, or at least several classes in chemistry and can give you good advice.