[FigureLLC]

jrow, i'll try pre-washing. it's not really something i've ever done on relatively clean looking metal, but after thinking about it, that's still probably helpful. it'd certainly be a shame to sand it first! (i actually smiled after the first few seconds i had it on the wheel bc it was polishing so nice).

mpierich, i searched for inclusions without luck. the inclusions in the thread i read didn't sound like what i was seeing. this metal was 3000 series aluminum sheet, and the "dirt" was a few isolated specs. maybe pressed into the aluminum during the rolling process?