hello, i did a little pressure washing at a house yesterday and used bleach and a pressure washer on it as well as acid cause it wouldnt budge with the SH but this black doesnt really come off. some of the tile chipped but the black seems to be stained. doesnt anyone have any idea how to treat this? Home owner says its never been painted. thanks.
Looks like slate to me… you aren’t going to get that color out as it occurs naturally.
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What % SH did you use?
Started with 2% and then after a pass came back with 6%.
Looks like it might be flagstone. I’ve had flagstone where I’ve had to use straight SH, around 10-12%. It’s about the only time I’ve ever had to go that strong.
The rest of the flagstone cleaned up just fine with the ~2%. I guess I could try nuking it with 12% but that just seemed like it would be such a waste.
Can anyone else confirm 12% is appropriate?
Do a test spot. No need to waste.
