I tried this technique out on my old Tau crisis suit with the broadside upgrade kit on. So a mix of resin and plastic, i'd say around 2+ years old.
Anyway i raided the other halfs accessories, found some nail polish remover, and cheered because it was Acetone free. the stuff ended up making the resin very brittle and the plastic had gotten weak enough around the joints that the arms snapped off with little effort. Not sure if it was the brand of remover i used, or that it was the old type of resin and plastic.
I will be popping to Superdrug today, to get the brand mentioned.
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After buying the superdrug branded stuff, it works like a charm. Though, i had real trouble removing Humbrol Matt black
http://www.modelzone.co.uk/150ml-spray-no-33-matt-black.html even after soaking it for well over half a day, it just didnt want to shift it :/
Still, if your base coat is good. it removes citidel paint with no trouble.