I bought a paste in the Old Keystone rock shop, a paste whose name escapes me at the moment, but it's the lapidary paste the window repair kits have in them; $3 per ounce. I polished on an unavailable front windshield of an English car. Harsh wiper marks about 6 inches long, but no scratches. It was one of those deals where I could see it working, but only after a half hour. I kept at it since it was working. I got it out, it couldn't be seen at all, but the warble I made in the glass doing it could not be ignored. Could the warble be polished out? I don't think so