New Razor blade, mist area with water as you go, most don’t use water when razor blading glass but your supposed to.

I don’t think plastic razor blades are your answer, you need something with a super sharp edge, brand new metal razor blade and mist with water as you go. If it were my piece of glass I’d be done already.

I think with how he described the incident and the distance the pin was from his spraying that most of the spray may have already dried a bit before landing on the glass. I doubt any chemical adhesion has taken place.

Clay bars are good too (especially because the surface of cars are rarely flat), though I think a razor on flat glass with mist of water would suffice here.

I would have left off the tape on the razor blade, once you put the tape on the two edges of the razor blade you no longer had a truly flat surface running over the glass.