Oxidation black spots removal

We all know about the pesky deeply stained black oxidation spots, the ones that survive days worth of time in the vibratory tumbler and walnut medium with no improvement. The ones that survive buffing where the rest of the untainted steel is at a mirror polish, etc. Sure they can be sanded off, but are there any other easier ways of getting rid of those spots?

Someone posted a teaser about a magic bullet product that may be available to wipe them away, but that sounds like it's a ways off.

Thanks.

Chris L