I try to improve, highlight details of my silver antoninian of Gordian III and unfortunately I degrade my coin, especially on the obverse side. Cleaning is always a gamble, sometimes we get, and sometimes we lose. It is cleaned chemicaly with apple cider and glycerin. Probably coin is firstly ruined in the soil, and then I accelerated this process. Before cleaning: After cleaning:
Too bad, never heard of cleaning coins with applecider. Gordianus Antoninius coins are only 40% silver , I once cleaned this Julia Domna denarius , made of a higher silver contence. used a mix of water& decalcification cleaner:
Acidic products should, in my opinion be left as a last resort. Distilled water and acetone are two of the best first methods to try. I have a Probus Ant that I have been soaking in distilled water for a few days and using wet toothpicks to remove grunge. It is working well. (Will have pics in the future.) Acetone will remove organics. I recommend verdicare as a great product for silver and copper alike. https://www.ebay.com/itm/VERDI-CARE...003042&hash=item41a67606f8:g:6XEAAOSwwbdWN-Kn I am working on a Gallienus Ant that it working great for.
Billon coins with a lot of bronze need to be cleaned like they are bronze coins. Otherwise you get this porous surface as all the copper gets leached out. I would not use anything acidic on them. I have several billion ants that came out of the ground all porous like this. The later the coin the worse this gets.
I don't clean my silver/billon coins and I've had middling results on bronze. On the bronze I've used distilled water/olive oil and a dental pick. I tried liquid descaler but it is very difficult to use successfully.
Bummer! I've heard that ammonia can be good when there's a fairly high copper content, but I've also heard warnings against doing this. Any thoughts on this?
I should have added "in my limited experience". I've always heard not on AE but I have not tried either. This Achaean league hemidrachm was covered with a thick black gunk and looked like it had been in a fire before treatment.
Let this be a lesson to all the quacks that promote cleaning ancient silver with lemon juice and other acids. When dealing with ancient coins, you have to be very gentle. Acids should always be a last resort, and when used, require constant supervision to avoid damage. Leaving a coin soaking in any acid for any significant time, even a mild one, is a recipe for disaster. Always try distilled water, then acetone, and if something stronger is required, try Verdicare...or even prolonged soaks in olive oil, and if that doesnt work and the coin has a 50% or higher silver content then move to 1 part ammonia and 3 parts distilled water (or another gentle substance like the one andres2 used) and only soak for a brief few minutes at most (when in doubt, pull the coin out, examine for any adverse reactions, and then determine if further soaking is needed). (Warning, Potin coins should never be exposed to Ammonia, so avoid cleaning provincial coins with that method).Avoid cleaning any bronze or debased coinage with it too. Any mild acids should be a last resort on the coin, and it should only be exposed to them very very briefly and the acid must be neutralized. Hopefully this lesson keeps other coins from being ruined. Also, I would have left OP coin in its original state as it was already a problem coin with crystallized surfaces. Some coins should just never be messed with.
