If this is the black currency I believe it is, it’s a scam. See the web site below. A quote from that web site:

“The alleged money is shown to the victim, who is told that the black coating or stamps can be removed by washing it with a special compound. The exotic and expensive mix of secret chemicals for cleaning money, which could be referred to as SSD Solution, Vectrol Paste, Lactima Base 98%, microtectine and Tebi-Matonic, is needed to “clean”a trunk or security case supposedly full of these illicit U.S. $100 bills and other millions stored overseas in a vault.

In fact, only a few real, blackened US$100 bank notes are shown to the victim, and the special chemical is ordinary cleaning fluid which reacts with the black mixture of Vaseline and iodine. The remainder of the material in the case is blank, blackened paper often made simply by photocopying with the lid up and cutting the sheets down to banknote size.”

Please read the rest of the info at the web site.

If this isn’t what you’re asking about, let me know and I do some more searching. But this is what I found.