Quote:
Originally Posted by bob47
I prefer plain concrete but a lot of driveways, like ours, develop black stains. This I thought was the residue of "black mold" but I was recently told by a neighbor that minerals in the concrete may be causing the stains.
This makes some sense because the stains have discrete edges and it hard to imagine how mold would grow on sun baked concrete with discrete edges. Also, I power washed my concrete so that it was perfectly clean and in a couple of years the stains were back in the same locations. "Wet and Forget" has had no effect on them.
So, if somebody has a suggestion for preventing these black stains on unpainted concrete, I would love to hear them.
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We’ve used Wet & Forget Outdoor Cleaner On our driveway. Over a period of weeks, the black stains disappeared, and it stayed clean. We love the stuff!