Not sure if this is something I could help the customer with… But I thought I’d put it out there if anyone knew or has an idea on what these stains are / ideas on how to get rid of these…
The first picture looks like the grout has spread somehow… These tiles are in an indoor swimming pool at an aged care…
The second /3rd picture is in the change rooms of the swimming pool… (I hope they upload in the right order)…
They really are not sure how they’ve appeared. Even if it’s not up my alley to clean up, if I give them some sort of advice, it could open up a door to pressure wash their exterior pathways etc at this aged care…
If anyone has an idea how these have come by or on how to get rid of this, any advice would be appreciated…
Hydrochloric acid may get rid of the staining. On those other two photos the tiles look like the glaze is gone on the high spots. Tell those old folks to quit shuffling their feet
Hey man, I have a similar issue. This client has these 4 year old planter boxes where they used black grout to seal between the stone cap and the concrete base. Some of them have consistent, nearly complete black stains on the concrete. From under where the stone cap attaches to the concrete walls, they used black grout to seal it. It’s surprising how much color has leaked out of the grout, but whats odd, is while some of it is nearly completely colored black, others have no change at all.
My theory is that when they applied the grout, maybe they did it on different days where there was more humidity or some other kind of environmental factors that caused the grout to not cure properly, which is why it might be leaking color straight down and nearly coating all of the concrete below it.
Do you think hydrochloric acid would remove all of this black? I tried hitting it with 180° water and a full pressure green tip. I also tried using F9 barc (I think barc has phosphoric acid in it, but not sure what else) and another product that I got recently from Sunrise Environmental (a product that is used to remove tar and other adhesives from asphalt). None of those methods did anything for it. Pictures attached.
