How to “clean” an old button

[StinkinLincoln]

I have an old cuff button that clearly has embossed text on it but is covered by black “paint.” I’ve soaked it for at least a day, or more, in hydrogen peroxide, then apple cider vinegar, then two different kinds of paint thinners, then fingernail polish remover, then paint stripper, and finally a car bug and tar remover all with no noticeable results. Any suggestions??

 

[Ammoman]

Do you have a picture of it? Before and after shots would be good.