I am trying to take this stuff off the rock because it looks gross and unsightly to say the least. I don't even know what this stuff is but it has eaten into the rock and formed these sores that I have no idea how to remove. I tried bleach.
The stuff sometimes glows under UV light and these rocks have about 30% moisture according to my pinless moisture meter. Is this mold or some kind of algae?
Flip the stone?
I agree with RMDman. Those red deposits are in the stone. They have been there for longer than humans have been walking. But maybe you could remove the stone, flip it and put it back? Same stone but I bet those red deposits are not through and through. The back side might look nicer.
Yeah but if you seal the stone after the flip you may slow oxidation. F9 FARC is the best rust remover you will find. It's a commercial product so do exactly what it says. Much safer that muriatic and other acids. You could use a film forming sealer on the iron then a matte sealer over the whole surface after flipping. Might as well use the bad surface to test everything and then flip.
