I'm hoping someone can help me. I have two basketball-sized dark brown wood stains on my concrete patio. They've been there for several months so they're pretty set in place. I've tried power washing as well as scrubbing but nothing is taking them up. I'm really out of options as to what to do. Could I buy a concrete stain and try to cover them? Will it even work in covering them? I've thought of laying a thin concrete slab over them but how thick should it be so it doesn't crack. Do I just cover it with outdoor carpeting? I'm really out of ideas. Does anyone have any solutions for me? I am open for all ideas. I can post a picture if that would help too. Thank you!