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Author Topic: Faked patina?  (Read 2122 times)

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Offline moonmoth

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Faked patina?
« on: August 27, 2006, 02:44:23 pm »
Greetings!

The coin seems to be OK, but the patina does not.  What do you think: brown paint?  What might be the best way to test and remove it?

Centenionalis of Constans, RIC VIII Cyzicus 77, 23mm, 3.6 grams ( a bit light, but many of them are).

Thanks ..
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jbaran

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Re: Faked patina?
« Reply #1 on: August 27, 2006, 03:58:49 pm »
You have the coin in hand, and would know best, but the patina looks OK to me.  If it's repatinated, it's a really good job.  I think the brown residue is left over from some cleaning chemical...but as i said, you have the coin in hand and believe you have seen a couple of these before ;)

Offline slokind

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Re: Faked patina?
« Reply #2 on: August 27, 2006, 04:13:12 pm »
I think the coin has been 'sealed' with some synthetic resin (would I be right to say 'polymer'?).  Or maybe some plain old shellac or varnish.  If they itch to make things shiny, I wish they'd stick to wax!  The crawling pattern captured in the macro photo does not look normal to me.  Pat L.

Offline moonmoth

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Re: Faked patina?
« Reply #3 on: August 27, 2006, 04:20:44 pm »
Hi, Joe .. Indeed, I have seen this sort of thing before, but not as strongly as this.  Perhaps I'm getting too suspicious, but it looks a lot like paint or varnish that has dried into little folds (where liquid might have pooled) which stand higher than the rest of the surface.  It would have been placed obverse down to dry, because this hasn't happened on the obverse.

If there's a cleaning fluid that does this, maybe the fluid has dried onto the surface of the coin.  What could that fluid be, and how could it be removed?  I'll try some obvious solvents and see what happens.

(Just seen Pat's comment) I agree completely!  Hands off!  Or I can take Ren Wax off very easily with white spirit.  And if it's anything else, it could so easily be something which adds a colour of its own, which is a type of fakery.

Bill
"... A form of twisted symbolical bedsock ... the true purpose of which, as they realised at first glance, would never (alas) be revealed to mankind."

Offline moonmoth

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Re: Faked patina?
« Reply #4 on: August 27, 2006, 04:37:20 pm »
I was right first time - it was paint of some sort.  White spirit brought brown gunk off onto my fingers, and I was able to brush it all off.  The coin has been cleaned down to the metal and then painted brown.  I will shortly be emailing the dealer .. (Not Forum, incidentally.)

It's much shinier now, so making it shiny can't have been the motive ..

Bill
"... A form of twisted symbolical bedsock ... the true purpose of which, as they realised at first glance, would never (alas) be revealed to mankind."

Offline slokind

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Re: Faked patina?
« Reply #5 on: August 27, 2006, 07:00:52 pm »
Bravo!  Rather a stripped coin requiring special care (merely silica gel near by), and left to itself to become less shiny, than one that I can't see!
Is white spirit the same thing as acetone?  Acetone is the major ingredient in ladies' nail polish remover.  Bruce was right to recommend open window, since it is volatile, but it doesn't eat metal.
Pat L.

Offline moonmoth

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Re: Faked patina?
« Reply #6 on: August 28, 2006, 12:42:25 am »
Pat -

White spirit is the standard thinner and brush cleaner for oil-based paint, sold over here by the litre.  It doesn't seem to be called the same thing in the USA.  Wikipedia tells me it is also known as "Stoddard solvent" or "Mineral Spirits" and says "It is a mixture of saturated aliphatic and alicyclic C7 to C12 hydrocarbons with a maximum content of 25% of C7 to C12 alkyl aromatic hydrocarbons."  There is more than one type.

It's easily absorbed into the body through the skin and lungs, so although it has low toxicity, it should be used with care.

Here's a World Health Organisation safety sheet that tells you more than you need to know, including many trade names it's sold under:

http://www.inchem.org/documents/hsg/hsg/hsg103.htm

Bill
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Offline Hydatius

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Re: Faked patina?
« Reply #7 on: August 28, 2006, 10:40:44 am »
In Canada we call it varsol.

Richard
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Offline moonmoth

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Re: Faked patina?
« Reply #8 on: August 31, 2006, 01:35:00 pm »
I had two coins with this "painted" surface.  This is the other one with its paint removed, revealing the horrors underneath .. it also revealed some small green blobs which look like part of the original surface covering.  You can see one on the forehead, and one on the bridge of the nose.  These had been painted over!

Bill
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Offline Joe Sermarini

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