Hey Lou,
Did you get an opportunity to work on this project further? We got a call to darken a stain on a stamped driveway - figured, no problem.....until wife told us husband put some sort of clear sealant on entire driveway. Having no idea of what type sealant is there, we're now looking for a stripping method. If we get the coating off, we're going to put down a darker grey.
Celeste