Hey guys, wondering if I could get some input on some tuff stains I have encountered. Location is Austin Texas. Some black stains on the concrete coming from under a limestone wall. Thoughts ?
Can you snap a picture of where it’s coming from so we can see the source? Looks like it runs across the street up road and to the right.
If it is in fact mineral stains an acid should work or would at least be what I would try first. I’d give oxalic a go and then move on to an aluminum brightener or F9 Barc. Watch for etching so don’t let it sit too long. Although, etching really shouldn’t be much of an issue there as long as the black comes up.
That almost looks like mildew. I know it feeds off of the limestone in the rocks on shingles. I wonder if the same thing is happening here and it has just accelerated the growth compared to everything around it. I’d try hitting a spot with a hot mix and seeing what happens to it
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What’s behind the limestone wall? I’m no stone expert but just don’t see that much staining coming from water running under a limestone wall. You’ve might’ve done that research already though. Is it just soil behind the wall?
I agree with @Bigbendwashpros that the last picture looks organic. I would definitely give some SH a try just to see. The top row of the brick definitely looks organic.
I am assuming it is just standard fill dirt. I am a nuby at pressure washing. What exactly is a hot mix?
Do this, get yourself A bottle of bleach or chlorinating liquid and pour some on it. If it turns brownish in color then it’s just black mold and can easily come up with a “hot mix” which is 50/50 to full strength sodium hypochlorite (found in bleach). We use typically 10-15% concentration in the wash world
