Any tips? Concrete patio stones

Tried 3% mix low pressure rinse. Maybe bump up the percentage and add a little caustic? Seen other posts where they used acid but I believe this is grime build up. No surface cleaner.

What are you trying to accomplish?

Clean the grime off. Hoping to have somewhat even colouring.

SH is used to remove organic material which I’m not seeing much of in the photos… it doesn’t matter what percentage you mix it at it’s not going to remove those white, black, and brown splatters, which look to be the focal point. Do you know what the white/black splatters are from? I’m guessing the brown is from when that column was stained. You will also need to use higher pressure to remove those splatters and also even it out if it’s embedded “grime”… if it’s faded because of other reasons there isn’t going to be much you can do to bring it back apart from staining/painting it.

Thank you for your time @OhioFloMo. I thought the darker stuff could have possibly been black mold. Appreciate the suggestions!

Hard to tell in the photo, but probably lichen, if that’s the case then 4-6% and a good scrub with a stiff bristle brush (if you don’t have a surface cleaner or pressure washer) should lift it.

I think he’s more after this discoloration, trying to blend everything together.

I’d be more inclined to think those are traffic wear spots where the original sealer was worn off. The other veterans on here can comment further.

Those white spots are just his soap, not lichens.

I was referring to the second picture they posted where it’s not wet. We were also talking about the dark spots being lichen, not the white… like I said hard to tell from the photo, but a lot of it looks like in organic material.

Customer was happy, I wasn’t exactly thrilled with the result today. I’ll return tomorrow for some after photos.

While we’re on the subject and I have your attention, is acid required to remove these white streaks or would 5% clean that up nicely on the pictures below?

I swear I’ve done my research just wasn’t satisfied with information I found as it did not attain to this exact issue.

You’ll need F9 BARC to scrub off the paint runs/white streaks on the brick.


Possibly Cleansol BC would work also i think.

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