A while back I was given a handful of uncleaned coins by a professor. For the most part they were barely identifiable slugs, although I was able to clean a couple into decent coinages (tiny Arcadiuses). This was also in the lot (very bad photo, but the only angle you can see any detail from): It's a Nicaea provincial, and seems to not actually be uncleaned. From what I can tell, someone must have tried to clean it in the past, possibly chemically. The patina is uneven, dark, and unnaturally dull, more than anything I have ever seen. This makes the details very hard to see except at the right angle. Despite this, they seem to still have good relief and detail beneath it. Normally I would never want to alter a patina, but I think it may already be too late for this one. Does anyone have any suggestions for salvaging it? Perhaps it might be possible to remove some of the patina from the features, to create a coin with contrast like this Nero I have, but I have no idea how I would go about doing that:
You can remove the patina from the raised area using a little dish-washing soap and a green, Scotch scouring pad. (Off brands generally don't work.) In my opinion, this makes the coin even less attractive, but it will make it easier to identify. Nowadays, however, if I have a coin with a really terrible patina, I use electrolysis to remove the entire patina. Over time (read: many years) the coin will slowly repatinate on its own. (I detest artificial patinas.) The problem it that you never know what's under the patina. Sometime you reveal a gorgeous coin with a lot more detail, sometimes you reveal an ugly, pockmarked mess, and generally you can't be sure in advance which you'll get. So maybe start with the scouring pad, and if you don't like the look of what you find up with, then go to electrolysis.
I thought of electrolysis, but I figured that was a bit extreme at first. I might try the Scotch pad. I hate to remove the patina at all, but in its current state it is pretty rough. The other side is even duller. Here it is not at an angle, and this is pretty much what it looks like in hand: Someone on Forum had suggested it might’ve been a failed cleaning attempt in the past. Anyway, I wonder if my Nero coin has just toned that way after having its patina removed?
First coin: soft brass bristle brush will slowly remove layers of grime and patina if you go slow it may bring out the details. Second coin: leave it alone and it will develop a more attractive patina on its own. Darkening takes a year or less. A true patina layer takes much longer but it will improve in a year.
I was using the Nero as an example of an attractive coin that didn’t have much patina at the high points. Wouldn’t dream of touching it further
It doesn't look as if any damage has been done to it, other than starting out pretty worn and then spending the next 1600+ years in the ground.
A quick question about electrolysis. I've tried it with a 9 volt battery but it didn't seem to have much effect. Should I be able to do some good with a 9v, or do you have to step up voltage to get results?
You need a good electrical connection to your coin or all you are cleaning is your electrode. You need to clean off to metal (or at least conductive surface) or not much happens. 9V is more than enough. If the surface of the COIN is not bubbling then you are not cleaning the coin.
It can take a while--15, 20 minutes even--for the coin to start bubbling. Here's a site I found with some information: http://www.mycoincollecting.com/collecting/cleaning-coins-electrolysis.html The only thing they get wrong is that they suggest using salt in the water. The salt becomes very corrosive to the coin once the reaction kicks in. You are better off using sodium carbonate, e.g. Arm & Hammer Washing Soda (not baking soda). You can usually find this in most grocery stores in the laundry detergent section, usually near the Borax. And don't add lemon juice, either. If you must use salt, then periodically stir in some baking soda (not washing soda--sorry this is so confusing) the neutralize the acidity, which increases as the salt breaks down.
Electrolysis is for coins with hard metallic corrosion or metallic deposits (not dirt) that nothing else will save. Usually they are totally corroded underneath but sometimes the deposits came from somewhere else and is just adhering to the coin. I think I saved one decent coin out of maybe 10 I tried this on, the rest were too corroded to be worth anything.
Yeah, it's definitely your last resort, but I've had a lot of success with it. There's a learning curve, though, and be prepared to ruin a few coins along the way. Probably the trickiest part is deciding which coins to zap and which to leave as is. You know what you might do is buy 10-20 uncleaned coins from eBay for $1-2 each and zap all of them. Then you'll get a feel for what zapping can and cannot accomplish.
