can you use oxalic acid on blue stone?
@bleachblaster I have never tried oxalic, but I did some blue stone last month. I contacted the stone quarry where the customer purchased the blue stone from. Their recommendation was to use Prosoco ReVive. I applied it straight with a pump up sprayer (and kept it wet) and then agitated it with a deck brush. It did kill the organics. Then it was rinsed with no pressure. It came out good and the customer was pleased. I think the end product would have been much better had it been sealed afterwards, but that is not something I do.
I have once with good results. If you put too much ox in it can turn the stone green though! I would instead use f9 barc
Edit-if you do end up using ox, use 4 Oz per gallon and up it if you need to. Don’t go past 8 Oz though.
i have these reddish brownist stains that don’t come out with SH and with a small surface cleaner going back and forth it does seem to bleed out the unwanted color but i think i have gone as far as i can go with the surface cleaner
pictures help in diagnosing a stain
the back patio has discoloring happening on just certain top pieces. some off it was coming out with water This is the front entrance and the center stones are older over the walk and steps. can the color come back? there are are a bunch of rust spots on one side but overall you can see the stones are worn from sun? salt? who knows.