Restoring a Volusian antoninianus from a French hoard

[Romismatist]

Hello Everyone,

A month or two ago, roughly forty 3d century silver coins, all antoninianii, showed up on EBay France. These included coins that would have been circulating concurrently and all had the same hoard patina (although some had been inexpertly cleaned). The hoard included coins of Herrenia Etruscilla, Philip I, Gordian III, Trajan Decius, Treboanius Gallus, Philip II, Otacilia Severa and Volusian. Based on this, I conclude that the hoard must have been deposited c. 251-3 AD.

This clutch of coins was posted by a seller located in Elliant, in Brittany, so I assume that the hoard was found in proximity to this location. In communicating with the seller (who appears to be more of an antiques seller, not a numismatist), he mentioned that he was selling these coins for someone who passed away and that they had amassed the coins over a number of years. Still, I'm fairly certain that these coins were all found together, as they have the same hoard patina. I'd be curious to see if you agree with this assessment.

I have been on the hunt for a passable Volusian antoninianus for some time... every one I came across in decent condition seemed too expensive, and others I could afford didn't appeal to me. I know that this is not a rare emperor, but I just hadn't come across a coin of his that I liked. However, within this hoard, there were at least three antoninianii of Volusian, and having had some success in the past at cleaning coins (although not necessarily at the level of @Roerbakmix), I decided to take the plunge on one of the Volusians to see if I could restore it to its former glory.

Here is how it looked initially:

And here is what it looked like after cleaning:

Apologies for the poor photos - I am terrible at taking them - but you should get the gist of the result. I was not successful in removing all deposits on the reverse, but the coin has a really sharp strike and the portrait is one of the best I have seen. Needless to say, I was pretty pleased with the result.

This led me to buy four more from the hoard to try my luck further: 

 

These results were rather more mixed: 

As before, I was not successful in removing all deposits, and in the case of the Treboannius Gallus and perhaps the Herrenia Etruscilla, the coins were struck with worn obverse dies. Still, they look a lot better than they did previously. I probably overpaid for all of them, but it was an interesting exercise at attempting to revive a few unattractive antoninianii and bag a decent specimen of Volusian for my "one of each emperor" collection in the process.

Feel free to your antoninianii or anything else you feel is relevant.

 

[ValiantKnight]

What was your cleaning method?

[Ocatarinetabellatchitchix]

Fantastic work Enrico ! It reminds me many souvenirs; I use to buy uncleaned lots in the past and had a lot of fun with them. Could you tell us more about the techniques you used for the cleaning ? Thanks for sharing. À bientôt. 
 

[hotwheelsearl]

My guess with silver base and greenish deposits, that various solutions of sodium hydroxide, acetic acid, and sodium thiosulfate probably did the trick 

[CPK]

Wonderful cleaning job!

[Ancient Coin Hunter]

Nice work!

[Roerbakmix]

I had the pleasure once to clean a similar hoard, the process of which I described here:

https://www.cointalk.com/threads/share-my-fun-describing-and-cleaning-a-small-roman-hoard.368534/

Cleaning 15 coins of more or less the same composition allowed me to experiment with different cleaning methods.

Edited August 28, 2023 by Roerbakmix

[Romismatist]

23 hours ago, ValiantKnight said:

What was your cleaning method?

It's actually a bit off the beaten track. Within North America, there is a product called "Gun Blue" which is used for cleaning firearms. It used to be available in Canadian Tire but is no longer sold (although you should still be able to find it on the Internet). I read online long ago that some people were using this to also clean coins. I've had some success using it to clean silver and billon coins. It darkens the coin (ie it's a reducing agent) but is very good at removing all kinds of deposits that would otherwise be difficult to remove and doesn't seem to be as harsh as with other chemicals.

To lighten the coins afterwards, I use a simple method involving placing warm water in an aluminum pie plate. If you dissolve table salt in the water and simply lay the coins in the water for several minutes, you can lighten the silver depending on how long you leave it in. I think it's supposed to be used for cleaning earrings and more pedestrian silverware, but it works okay for coins as well. They don't come out as shiny and burnt as with electrolysis. 

I'm wondering if I can remove the remaining copper deposits using @Roerbakmix's method of using hot citric acid for a short period of time. I've used citric acid before to successfully remove copper deposits from other coins. That would probably finish the job properly.

[Factor]

Volusian is amazing, excellent cleaning! With silver coins I typically apply a drop of lemon juice for a few minutes, closely monitoring the effect. But I don't know how it will work with lower silver content coins.

[shanxi]

For good silver I also use EDTA, a compexant for 2+ charged cations. It's able to remove Cu2+ Ions nearly without effecting Ag+ (the silver patina). 

Faustina Minor
AR-Denar, Rome
Obv.: FAVSTINA AVGVSTA. Draped bust right.
Rev.: MATRI MAGNAE, Cybele seated right with branch and drum, behind her a lion.
Ag, 3.83g
Ref.: RIC -, CRE- (this type with Cybele right is only know for Aurei)

cleaned and uncleaned

 

 

Edited August 29, 2023 by shanxi

[Romismatist]

On 8/29/2023 at 12:21 AM, Factor said:

Volusian is amazing, excellent cleaning! With silver coins I typically apply a drop of lemon juice for a few minutes, closely monitoring the effect. But I don't know how it will work with lower silver content coins.

I tried the hot citric acid and it did the trick on the Treboanius Gallus and Philip I antoninianii. It also cleaned up the deposit on the Volusian reverse. Will take and post pictures later. Another tool to add to my coin-cleaning arsenal... always learning on this forum!

[Roerbakmix]

Weak organic acids on debased (copper rich) coins can certainly help. Always neutralise the acids when finished; otherwise the reaction will continue.