I received some (apparently) bad advice and spent a lot of hard time and messy effort removing a thin layer of cutback using paint thinner from a concrete slab. Should have researched this better first. It left what looks like a stain on the slab, now I hear that chemical residue may be a problem. From what I now read on various sources online, I'm not sure if this is a problem or not -- seems to be a lot of different opinions out there.
Should have researched this better first. Anyone have an opinion on how to proceed? Soap and water? Drysweep? Just lay right over it (we are using a modified thinset)? Any other good ideas?