Probus - Clementia Temp

I think you've done a really good job so far, but don't stop yet. Keep soaking. For a long time even. Instead of a safety pin, use wooden toothpicks. They're less likely to damage the coin's surface. I can't see the mint mark from your image, but KA is the mint mark for Serdica.

Gil-galad: Your patience has been rewarded. The 'after' is much better than the 'before'.

I have used tooth picks on similar coins, but to no avail.
Using a safety pin may seem to be a rash thing to do, but with LOTS of patience, ain't so bad on re consideration.

A safety pin is much easier to hold. The technique is to press the point of the pin in the middle of the verdigris or encrustation or whatever, and apply downward pressure, WITHOUT scraping. Tiny little pieces of gritty substances will just fly off.

It takes literally hours to clean a coin in this way, and only black Roman bronze coins really respond to this treatment.

I have cleaned only one cheap Roman bronze coin in this way, because all of your patience and time will be consumed. My result is about as good as the coin seen here.

The black finish on the coin is the result of immersion in olive oil over a long period of time. The only coins I have considered for immersion in olive oil were already black.

I am at a loss as to how to remove the black colour. Perhaps gentle rubbing with fine powdered anhydrous clay may help to lighten it, remove some of the residual olive oil, and help to attain a pseudo 'desert' patina. That is only a guess on my part however. Experiment on any other cheapie black late Roman bronze coin to prove / disprove this.

KA is not a mint mark but just an indicator that the mint that produced it was one that used the Greek version (K=20 A=1) of XXI to indicate the alloy. If you want to attribute the coin to mint, you will need to check which of the 'KA' mints issued this type and legend combination and compare the style of the coin to them if there is more than one. In all honesty I can't tell with the coin in its current state. Old RIC (I'm anxious to see what the new version will say) says Tripolis used both KA and XXI but did not use officina letters while Serdica would have followed the KA with a workshop letter. This coin has a lump of crud there which needs to go to see if there is a letter beneath. I suspect there will be so the coin may be Serdica but I am not into these deeply enough to make the call on style alone.

These coins are not like US with 'open markings' in every case. Under Probus a few mints gave a city initial on some coins but most require learning some trick.

i think its looking good!

looks like you got your bronze spot at 7 o'clock tyring to scrap off that little mound of stuff? If so, I did the same thing last week. Had a hard light colored deposit, scraped like mad thinking bare bronze wouldn't look worse than an encrustation...and got the bare bronze. Anyone know how to deal with those little things?

as far as what appears to be dark stuff on the surface...i don't know what to do with that sometimes. if its dirt it fits on the surface like a glove and doesn't obscure details..but doesn't look right either...

look at this coin I gave up on....











Black looks like patina, but there is the green underneath...at least in some spots. but that black sure doesn't want to come off...you can see some bare bronze there at 7 o'clock..which is when I gave up and put some wax on it.



Advice appreciated...thanks.