We have national elections coming up in two days, and like every time the election officials will mark people's thumbs with a dab of some purple solution that leaves a brown stain on the skin (and thumbnail) that takes a while to grow out. I'm pretty sure that's a potassium permanganate solution - that stuff behaves exactly the same.

Now I'm not into electoral fraud (there are other controls in any case) but I dislike having that stain on my fingernail for a month or more afterward. Previously I've had partial success by rubbing butter into my skin, but the stain still gets through. I've also tried making some plain old sugar or even glucose available, hoping that it would get oxidized first, but I can't conclusively say that that worked.

Any other tricks to avoid, or at least strongly mitigate, these stains? There's a window of about a minute or two where the purple solution sits on the cuticle while I'm unable to do anything about it.


1 Answer 1


If it is permanganate, the brown $\ce{MnO2}$ stain will decolorize and solubilize in acidic reductant - lemon juice, perhaps boosted with a little crushed and dissolved Vitamin C. I'd go for crystal/gentian violet or Disperse Red 9 as a marker, or a reactive Cibacron or Procion dye.

Cthulhu for Fearless Leader! Why vote for the lesser evil?

  • $\begingroup$ I dissolved some citric acid in water and immersed my thumb in it for a while. The stain seemed not to be as bad as in other years, although I did abrade some more off. $\endgroup$ May 8, 2014 at 12:44
  • $\begingroup$ You need bvoth the reducing agent and the acid, hence citrus juice that contains both. $\endgroup$
    – Uncle Al
    May 8, 2014 at 18:32

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