I used 3M Safest Stripper on my crystal castles, which was totally painted by a thick coat of black paint. I applied it on small sections at a time and let it rest for about 10 min. Then scrubbed the paint off. Scrubbing was the hardest part, since you do it with a plastic spatula and plastic fiber scrubber in order to preserve the side art. I ended up with a slightly dull sideart, but absolutely clean.