FORVM`s Classical Numismatics Discussion Board

Numismatic and History Discussion Forums => Coin Photography, Conservation and Storage => Topic started by: Ghengis_Jon on April 30, 2008, 06:00:20 pm

Title: Medic!!!! Question from the ER
Post by: Ghengis_Jon on April 30, 2008, 06:00:20 pm

This is a painful experience for me.  I received this coin earlier this week.  (Top photo is the seller's shot)  As I took it out of the flip it shipped in, a chunk of the patina broke off (aaarrrrggggghhhh!).  The coin is nearly 3mm thick with patina accounting for about half the thickness.  Under the patina was revealed to be a core of metal that has a white dusty appearance.  The second shot is how it currently looks and the last is a close up of the damage.

The rest of the coin is in good shape (o cracks or chips).  But the 'powdery' metal concerns me.  How should his coin be preserved (as opposed to conserved)?  Should I worry about moisture in the air and further coin decomposition?  Wax will not buff out imo and would be unsightly.  Should I seal the exposed area with polyeurathane or the like?  Should I just live with it and do nothing?

Opinions please from the esteemed membership.  Thanks, Jon

Title: Re: Medic!!!! Question from the ER
Post by: Ghengis_Jon on April 30, 2008, 06:01:29 pm

Close up of the damage

Title: Re: Medic!!!! Question from the ER
Post by: museumguy on May 01, 2008, 08:02:12 am

Jon,

Since you are in Michigan I would take advantage of the terrific conservation staff at the Detroit Institute of Arts.  I'm sure they would be more than happy to give you some free advice and they certainly know what they're talking about.  I've attached the link to their online contact form.  You can send it directly to their conservation department.  Good luck.

Steve

http://www.dia.org/museum_info/contact_us/index.asp

Title: Re: Medic!!!! Question from the ER
Post by: Robert_Brenchley on May 04, 2008, 12:17:02 pm

I've come across this when I dropped a Carausius, in its flip, onto a carpetted floor, and it chipped. I think it's the same thing in both cases; the metal has been completely corroded away leaving nothing but carbonates, which are excessively fragile.

Title: Re: Medic!!!! Question from the ER
Post by: Ghengis_Jon on May 09, 2008, 08:52:42 am

Did you 'treat' the chipped coin in any way after that?

Title: Re: Medic!!!! Question from the ER
Post by: Ghengis_Jon on May 16, 2008, 02:13:31 pm

I received a response from one of the conservators at the DIA...

The metal in the coin has largely become mineralized probably as a result of being buried. This would make the body brittle and powdery. Although I don't think you need to do anything except keep the coin dry, you could brush on a bit of 3% Paraloid B-72 acrylic resin in acetone or ethanol just at the exposed area to consolidate the edge. B-72 is available on line, and you can get solvents at your local hardware store.

Title: Re: Medic!!!! Question from the ER
Post by: Robert_Brenchley on May 31, 2008, 05:00:39 pm

Quote from: Ghengis_Jon on May 09, 2008, 08:52:42 am

Did you 'treat' the chipped coin in any way after that?

Sorry, I missed this one. No, I didn't feel I could do anything with it. It's a common and inexpensive coin, and illustares corrosion very nicely!