The thing about bleach, turpentine, mineral spirits, etc. is that I'd have to deal with some unhappy combination of sticking my hands into them (well, okay, I can probably get chemical-resistant Nalgene gloves at the hardware store these days), having fumes evaporate out during the soaking period, breathing more fumes while I work with it, and safely disposing of the stuff.

I dunno, when I got down to the damp bottom of the bowl, the rubber cement that'd stayed wet overnight had become soft and easily rollable off. Of course, by then I'd already painstakingly art-gummed all the magatama that were sitting on top of those, whose rubber cement had all dried back out. A lesson to keep in mind for next time, if there is one. Grumble.