Samaria - Dolphin And Lion

Wow, that is why buying 1000 cull lots are fun! Quite a find. The Roma Numismatics one I found says "unpublished" for it as well. (Text below) I'd think you want to carefully stabilize that bronze disease as it could have come from a recent overcleaning. So I suppose careful toothpick work and a wax to seal from the air?

"Samaria, uncertain mint Æ9. Circa 375-333 BC. Dolphin leaping left above conch(?) / Facing head of lion within shallow incuse circle. For an obol of similar types, cf. CNG MBS 63, lot 781, CNG MBS 69, lot 638 & Gemini VI, Unpublished."

I agree!

I usually use just distilled water, which is the slowest way, but I have been meaning to try this method. I am uncertain why a mixture of bicarb and carb is used, as either seem to be an acceptable chelator for the purpose. If I can acquire better chelating agents, I will also try those.

I will alter the method slightly. The first round, I'll boil the coins up in the mixture, then take them out still hot and wash them with distilled water (as opposed to leaving them in the mix for a week). The first round of treatment should only be for the surface, in my opinion, and should not allow an ion laden solution to penetrate the coin. After that, I will leave the coins to soak in the mixture for an extended period of time, with regular changes of the solution.

After the treatment, I won't use isopropyl alcohol. I will bake at a low temperature for perhaps 30m, then leave to cool in a tupperware dessicator (using calcium chloride if I can get it, silica get otherwise). This should drive out the water more effectively.