I've been told acid would take the lime stains out of our sandstone walkway. Do you have a better safer solution?

Asked by May Drinkwine
Putnam Station, NY

Last September, we had sandstone put down for an outside entrance way. It was too cold too seal it last year and it's been so hot this year I never attempted it. Now we have lime stains (whitish in color) mainly on the grout. I've been told acid would take the stains out but I don't want to touch the stuff. Do you have a better solution? Also, it looks like water stains around some of the stone, anyway to take those out? The stone if very porous and I was told not to use anything acidic when we bought the stone. I sure hope you can help as I've purchased some impregnator and before I put it down, I would like to try to get those stains out.


Answered by Erik Henry

Brownsburg, IN

ELH Construction LLC

September 11, 2012

I can't say for sure, but if it was to cold to seal the masons may have used a calcium compound in the mortar to keep it from freezing. This compound will effervesce and a chalky powder will stain the mortar.

There are products designed for cleaning this but are acid based products. You will need to dilute the Muratic acid that is used in pools to balance the water PH.

Don't be scared, just careful.

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