Efflorescence and calcium on painted concrete wall

hi everyone. ive been doing some searching on google and cant really find the answer to my question. i have a bid for a general contractor who wants some hard water stains cleaned off of a red stripe that is painted on a 28’ tall concrete wall. Im sure the WHOLE wall needs power washed but as far as removing the hard water im not sure which chem to use. obviously an acid, but household acids are the only ones that sound weak enough to not damage the paint, yet using vinnegar to clean the wall just seems…like it wouldnt work, lol. what do you all think?

Chris Rasband
Elite Concrete and Trim Restoration
Salt Lake City, Utah


These folks make great restoration chems. We’ve used them for a few years. You can email them pictures of what you’re dealing with and they are more than glad to get you the right product.

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x2 mike@eacochem.com

As far as the tilt-up concrete goes, it’s hard to say what you need without pics…

Thanks for your replies guys here are 2 of the photos that show the issue fairly clearly. Runnoff from the roof because of a drip edge that they didnt install correctly.

Still hard to say for sure but my first guess is actual efflorescence. Hit some NMD-80 diluted 4:1 on the surface. I’ve worked with similar material and that streaking looks just like the streaking present on the stuff I was working with.

If you can get up there, take your hand and smear it around. If it smears, it’s efflo. If it doesn’t it’s probably white scum or lime run.

*Edit: this will be something you will have to spray the whole wall to be uniform.

Thanks trey. I’ll have to see if I can make my way to the roof. If it is lime run or white scum is there a paint safe product to help soften it?

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White scum pre-soak or calcite pre soak followed by NMD-80. You have to do a small test area first. Call Mike at EaCo and he can get more into specifics.

Ditto, call eaco chem and show them the photos you posted here.
I’d upsell the job and tell the GC you’d be glad to clean the windows and remove the label stickers while your all ready there :slight_smile: