Received from Morris Odell at 10/13/2021 23:31 UTC:
Alas not, I've tried both acetone and IPA and they don't touch it. I'll try MEK but I'm reluctant to try paint stripper because of methylene chloride toxicity.
If you try methylene chloride, just use it outdoors where it will work as well as it does inside, but you don't have to breathe it.
I suggest something alkaline... like dishwasher detergent powder... though an alkaline drain cleaner would probably be better. A couple of tablespoons of the cleaner in enough water to just cover the board all in a glass dish. Soak it a few minutes (drain cleaner) or maybe 15 minutes (dishwasher powder) then rinse it carefully (no splashing) down the drain and then the resist will probably come off with a pot scrubber.
Educated guess, not guaranteed. If you can look up the product on the Internet you would have something more specific to go on.
Good luck.
JimH
