We recently had the windows redone in our 1920s-era condo and, in the process, had a wall opened up to reveal windows that were walled off from the inside some time in the 30s. However, the grime on the exterior of the windows will not come off (action shot below). We've tried:

  • Windex
  • Goo Gone acetone
  • Soap and vinegar
  • "Magic Eraser" sponges

Whatever substance has bonded itself to the windows, it's not just dirt. I'm guessing something like tar and soot perhaps? Regardless, I'm wondering if folks have encountered similar challenges and how they've tackled the issue.

Interior view through dirty window

  • 3
    Try scraping it with a single edge utility blade or razor blade.
    – JACK
    Sep 27, 2022 at 16:58
  • Ah yeah! I forgot to mention I did take a pocket knife blade to the gunk which didn't do much but I forgot about the dedicated razor bladed scrapers. I'll give that a go and see what luck I have. Thank you!
    – mjbraun
    Sep 27, 2022 at 17:08
  • 3
    Can you tell whether you may be seeing a chemical-induced hazing or mechanical abrasion to the glass, rather than a coating/substance as assumed?
    – Greg Hill
    Sep 27, 2022 at 17:51
  • 2
    What a fun discovery! Yes, this may be etching and not deposits. As a test, try polishing with car wax.
    – isherwood
    Sep 27, 2022 at 19:09
  • 1
    There's always the ultimate option of replacing the panes of glass. Yes, a pain, and money, but it will work!
    – Ecnerwal
    Sep 27, 2022 at 19:26

1 Answer 1


A bit delayed but the answer is "it's chemical-induced hazing" and, unfortunately, using a scraper changed basically nothing. There was paint on the glass for years, as well as stripper used to remove said paint, and either or both may have been the culprit. Alas, but there will be something in front of the window so the hazing won't be visible.

enter image description here

  • I wonder if some car wax and a powered buffer would do anything.
    – spuck
    Nov 1, 2022 at 20:59

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