Tried 80% alcohol (windshield wiper), which had zero impact. Also tried hydrogen peroxide 3% (for cleaning wounds) just in case that works, also no impact. Acetone ultra strong nail polish remover also zero impact.
Scraping with nails seems to work best of these things, but doesn't really work. Yet to try 99% alcohol :).
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=== Update (03/22/2017) ===
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At the moment I used acetone and then scraped, followed by using some oil to clean it a bit more - stuff we had in the house. Still not good, but almost OK.
Tried 80% alcohol (windshield wiper), which had zero impact. Also tried hydrogen peroxide 3% (for cleaning wounds) just in case that works, also no impact. Acetone ultra strong nail polish remover also zero impact.
Scraping with nails seems to work best of these things, but doesn't really work. Yet to try 99% alcohol :).