How do you remove false patina?

spoon · January 10, 2009 5:21AM

Got this one around New Years from Italy. Most of the seller's coins seemed to have this fake green patina. I'd never dealt with it before, never owned a coin with it, so said why not and went for this common cheapo.

It's been brushed to death and poorly covered up with fake green patina. What's the best way to remove the fake stuff and get it on its way to retoning?

BTW, the coin is a denaro of Manfred, King of Sicily, Brindisi mint, c1260, MEC XIV-602.

Just for comparison, this is one with a natural patina:
(Also, Manfred, but Messina mint, MEC XIV-621)

johnsim03 · January 10, 2009 8:41AM

You can use acetone or alcohol to try and remove the fake patina.

These items will remove MOST, but NOT ALL chemically-based patinas, IMHO...

This is a complicated issue, and if the patina was not removed by acetone or alcohol, it probably
means that heated acid, or other chemicals were used in the repatination process.

I would probably just leave it be, but that's just me!

John

lordmarcovan · January 10, 2009 8:51AM

I must admit that though I have heard of falsely-applied patina, I've never knowingly encountered it before. I wouldn't have suspected that, unless something happened to resemble the stories I have heard of false patina smearing off a coin's surfaces after it got hot under a lamp or something. Does this stuff come off in your hand? What was the tell that it was fake?

spoon · January 10, 2009 9:03AM

John,
I think I will just try acetone. I'm just worried if I try the wrong stuff it'll be reactive and bubble up eating away the metal.. this is something new to me!

LM,
I've heard of it too, but always thought it was something professional cons did with such skill that I'd never notice

This one is just egregious. It doesn't just rub off, but it really looks like Ajax or Comet pasted on (don't think it actually is tho). You can kinda tell in the pics that it lays over the grooves left by the harsh cleaning, which to me is tell-tale that it's modern. That, and I've never seen any Sicilian coinage of this era quite so green. Usually the patina is earthen like the bottom pic and if green at all it's a dark green, not this neon pastel stuff.

But this is a learning experience. That's why I bought the coin

spoon · January 10, 2009 9:08AM

I just poked at it with a toothpick and it comes off a little bit, kinda like paint.

Next up, acetone!

lordmarcovan · January 10, 2009 9:38AM

I guess this simply means that you have developed an eye for your area of specialty, and learned to recognize something that departs from the norm. In a word: experience.

Experience counts for an awful lot.

I like the earthen patina on the second example you posted. The green on your topic coin doesn't bother me, particularly, at least to view it in the pictures, but I agree that the earthen patina is better. It reminds me of the "desert" patina our conversation partner, johnsim03, turned me on to in the late Roman bronzes. I do love that look.

Ricke · January 10, 2009 10:14AM

Pardon the question - I'm not familiar with these at all.

Wouldn't a fake patina be an indication of a fake coin underneath?

spoon · January 10, 2009 10:47AM

Not necessarily. Sometimes it's used to cover up a harsh cleaning, which seems to be the case here. Really, it's kinda like AT for ancients. There are several different ways to apply fake patina, even fake desert patina. I've never encountered any aside from pics online (see here for several examples, these are indeed fakes). This case seemed especially sloppy so I figured I'd use it as a learning tool.

lordmarcovan · January 10, 2009 11:21AM

<< <i>Really, it's kinda like AT for ancients. >>

Exactimundo. I never thought about it that way, but that is a very apt way of putting it.

spoon · January 10, 2009 12:29PM

Well, acetone was a no-go. Since this is a test case, I decided to go the harsh route. I'm very much against tampering with coins, but only so much can be learned by reading. Some might call this an atrocity, but the patient was already dead. Some uglies were encountered, as expected, but not too bad.

Now I've gotta figure out how retoning works!

Before and so far:

MacCrimmon · January 10, 2009 1:12PM

Chuck this into a Dremel, and your patina

lordmarcovan · January 10, 2009 3:03PM

Hate to admit it, but I prefer the "before" picture to the "after".

The fake patina didn't bother me much, seeing it in pictures. In hand it might have been a different story, but I thought it looked OK.

I suppose it does look more "natural", now, and maybe it will retone.

Blackhawk · January 11, 2009 2:29AM

I experimented once with burying a cleaned bronze coin in one of my wife's flower pots. I didn't think about it for over a year, but when I took it out of the dirt it looked pretty good.

7Jaguars · January 11, 2009 3:28AM

In my experience with bronze, and even silver, a mechanically or chemically cleaned surface tends to oxidize a bit more rapidly than one might anticipate...

olmanjon · January 11, 2009 10:26AM

I liked all of them. As you can see they are not my speciality. Even so, seems like a lot of detail for a coin that old. Olmanjon

lordmarcovan · January 11, 2009 12:57PM

<< <i>I experimented once with burying a cleaned bronze coin in one of my wife's flower pots. I didn't think about it for over a year, but when I took it out of the dirt it looked pretty good. >>

You know, I've thought of doing this. We have window box-like flowerpots hanging on the porch railings, and our well water that ladymarcovan waters her flowers with has plenty of sulfur in it.

How do you remove false patina?

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