Ancient Coins
Date: Wed, March 9, 2005
Nick, who occasionally posts to the forum here, has taken up a new hobby. He cleans ancient coins. And by ancient, I mean Roman. It seems that people in antiquity would bury their money in the backyard if they were going off to join the Legions or whatnot, then for whatever reason they never dug them back up. 2000 years later, some farmer is tilling his field, and there's a stash of coins. You buy the coins on Ebay (or wherever), and they come as dirty little disks of bronze encrusted with dirt. You then clean it, and try to figure out who minted the coin. Interesting Stuff.
Nick:
Cool. Much better then the one I wrote up, the link is better to, though I don't like the authors view on several things (particularly electrolysis and the use of artificial dyes to get the coloring of a patina after it was removed).
1.) Electrolysis is bad for the coins. Due to the nature of electrolysis the reaction occurs on the coins, that reaction eventually does displace the dirt, but in the process it horribly pits the coin (look at all the pin-prick type holes on the coins he displayed). You might be able to seel such a coin on ebay for a couple of bucks, but most coin collectors will snub their noses at you, and if it was a rare coin beat you to death in your sleep with a wet noodle.
Electrolysis CAN be used on coins, but it's not as easy as most people think. If you see people talking about (V)oltage, completly disregard everything they say. It's all about the amprage, and to do this correctly you are going to be dealing with some very small numbers. Basically, if you can see a reaction taking place, you screwed up. Yes, museums use this to clean coins to the metal (grumble) but they are using such low-amps that you can't see any reaction in the vats. This is NOT supposed to be a quick fix, and don't buy an electolysis kit on ebay and expect to keep your coin intact.
2.) The patina is a good thing, and it's not some big secret. First off it does a lot to prove authenticity of the coin. Patina's develop over time to protect the metal of the coin (otherwise there would be no coin left). It's not likely that a coin can survive the process of developing a second patina as this process does corode the metal. Secondly, a lot of the detail can be preserved in the patina. Often times removing the patina will cuase loss of detail since the patina held the original image, but the metal of the coin had long-ago lost that detail.
Just some words to chew on.
Dave:
I think we both wrote articles at about the same time, I didn't mean to skip over yours at all. I would have used it instead of mine actually, why duplicate work? :)
You always hear about this kind of thing happening on Slashdot all the time, now I have my own little example... hehe
You always hear about this kind of thing happening on Slashdot all the time, now I have my own little example... hehe
Jim:
I can check with the curator of collections at our museum but I'd bet she'd have an absolute fit over the idea of using electrolysis to clean any metal artifact, particularly something from antiquity.
From a museum standpoint, the patina is part of the artifact's provenance (a fancy word for its history) and removal of any provenance ruins the historical value of the artifact.
Dave:
So, what did she have to say?
Jim:
After she said, "You're kidding, right?" she told me that no collections manager/curator that she knows would ever consider using electrolysis to clean anything from antiquity. It alters the metal on the molecular level and is a very bad idea.
I told her that someone recommended cleaning coins from the era of the Roman Empire in this manner and she just shuddered.
So, I think from an historical and curatorial perspective, electrolysis should be left to old ladies with moustaches (like my Aunt Wilma).
Nick:
Awsome. That is great to hear, after digging through a ton of coin collector sites there seemed to be two common perceptions about museums:
1.) They used elecrolosys(sp) to clean all there coins to the bare metal.
2.) They didn't give a pigs fart about the patina.
I am glad that both of these turned out to be misconceptions. I did a lot of digging around before deciding on a cleaning method for my coins, after viewing examples of everything (including coins cleaned through electrolosys) I adopted a purely machanical methodology involving LONG soaks, a microscope, and a diamond-dusted dental pick. Combined with a very conservative idea of what clean is, I think I do an ok job of cleaning.
But yes, people do use electrolosys. The person you where speaking with would probably cry...
1.) They used elecrolosys(sp) to clean all there coins to the bare metal.
2.) They didn't give a pigs fart about the patina.
I am glad that both of these turned out to be misconceptions. I did a lot of digging around before deciding on a cleaning method for my coins, after viewing examples of everything (including coins cleaned through electrolosys) I adopted a purely machanical methodology involving LONG soaks, a microscope, and a diamond-dusted dental pick. Combined with a very conservative idea of what clean is, I think I do an ok job of cleaning.
But yes, people do use electrolosys. The person you where speaking with would probably cry...
Cecilia:
At least one of the posters made it clear that it wasn't for potentially valuble coins. How the heck are you supposed to tell BEFORE you clean it!?
Nick:
Basically where it was dug up I would persume. This particulare coin isn't one from antiquity, but I used it for an example anyway, since it was the first one I found that had pictures of the entire process.
Goto ebay and do a search on anchient coin (or go to the coin->Roman Imperial section) and take a look. The people who use electrolysis are easy, their coins are completly clean and they look like they someone took a needle and got friendly.
Cheers.
Goto ebay and do a search on anchient coin (or go to the coin->Roman Imperial section) and take a look. The people who use electrolysis are easy, their coins are completly clean and they look like they someone took a needle and got friendly.
Cheers.