Just a quick addendum...
I too had the same problem. A white band with a blue-ish/purple-ish ink stain on the bottom of my band, which I got from keeping my arm resting on a notepad where I had just taken down some notes (argh!). I tried most of the same treatment methods you guys reported here; water, hydrogen peroxide, vinegar, lemon half, and a stick of "Gallseife" (Swiss soap that gets out just about anything). It seemed that the lemon half did the most to reduce the stain by about 30% after about 10 minutes of treatment.
I read that acetone would probably be a bad choice, but found some non-acetone nail polish remover at Target (generic brand), with the main ingredient ethyl acetate. I really wasn't sure if this would be any better, but gave it a try. Within about 10 seconds the stain was 95% gone, and now I have to stare at the band to find the ink stain remnants. The band itself is in good condition, although it does feel a little bit different than the other band I did not subject to the various treatment methods. It is very hard to tell a difference though, and I
suspect that the treated band might simply be cleaner than the other band. Someone with more knowledge of ethyl acetate and fluoroelastomer, might able to speak more to the compatibility of the two substances. I, however, am really happy with the results.
If this happened to you, and you're not getting the right results from the magic eraser (or any of the other suggested methods), ethyl acetate might just be the right solution for you.
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