I recently moved into a new house. Several of the exterior vinyl windows have these strange fingerprints on the outside of the upper pane just above the meeting rails. I've tried cleaning them with a razor blade, soap and water, Windex, Simple Green (full strength), Goo- Gone, Goof-off and Turpentine. With tons of elbow grease, I'm able to get the fingerprints off - with no one product obviously dissolving whatever the fingerprints are made from. Still, when I go to clean the window afterward, just spraying a soapy solution to squeegee, you can clearly see where the fingerprints are - even though the window is mostly clear. I have 19 windows to go and dread the thought of having to spend 15-20 minutes on each getting these prints off and even then
- not really getting them all the way off. Any ideas what they could be and what would dissolve them without damaging the glass or windows?