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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

mjbraun
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    Try scraping it with a single edge utility blade or razor blade. – JACK Sep 27 '22 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 '22 at 17:08
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    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 '22 at 17:51
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    What a fun discovery! Yes, this may be etching and not deposits. As a test, try polishing with car wax. – isherwood Sep 27 '22 at 19:09
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    There's always the ultimate option of replacing the panes of glass. Yes, a pain, and money, but it ***will work!*** – Ecnerwal Sep 27 '22 at 19:26
  • This is a good point about the etching: as a silly test I took some nose oil and rubbed it on the glass and it looked clear (if you're old enough to recall struggling to read data off scratched CDs, this was the hack for that). Curious, though: what environmental products would lead to hazing of glass? – mjbraun Sep 28 '22 at 16:07

1 Answers1

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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

mjbraun
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