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Author Topic: We all love patina. Tips for improving a natural patina?  (Read 950 times)

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Offline Daniel J

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We all love patina. Tips for improving a natural patina?
« on: May 25, 2020, 01:26:27 pm »
Okay so we all love our patinas. Green, red, brown, black, desert etc. Any thoughts on helping coins improve their patinas naturally?

I’ve got a number of these provincial issues that appear fairly black in hand, though when you look under a scope or with bright light a nice green can be seen underneath the black. Any tips on how to bring that green out a bit more?


Offline otlichnik

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Re: We all love patina. Tips for improving a natural patina?
« Reply #1 on: May 25, 2020, 06:21:33 pm »
Black is the new green!

I love black patina coins.  They look awesome in hand, though they are among the hardest to photograph well.

Without a close examination of the coin it is hard to give you advice.  Why is the green under the black??

Natural process that went green then is turning black?  If so that is the patina, best to leave it.
Fire damage?
Tar or some weird mud?
Residue from some wax or treatment gone wrong?

Personally I wouldn't risk anything unless they are stick in hand.

SC

SC
(Shawn Caza, Ottawa)

Offline Daniel J

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Re: We all love patina. Tips for improving a natural patina?
« Reply #2 on: May 27, 2020, 05:22:32 am »
Appreciate your input. I’m not sure if the green is really under the black. They aren’t sticky and the black doesn’t just come off.


Offline Joe Sermarini

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Re: We all love patina. Tips for improving a natural patina?
« Reply #3 on: May 27, 2020, 08:46:12 am »
There are other things involved but, generally, brassy coins turn blacker, coppery coins turn greener. Many are somewhere in between and have areas that are blacker or greener. I don't recall ever seeing a black layer over green. I don't think there is any way to make a black patina greener.   
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Offline Daniel J

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Re: We all love patina. Tips for improving a natural patina?
« Reply #4 on: May 27, 2020, 11:29:56 am »
I can’t tell if the black on the green. They look very dark green like a rich forest green almost black. But when looked at up close or with added light a brighter green comes out a bit more, as if showing through the black.

Over the centuries how do you think the best patinas come to be. Is there an ideal scenario??

Offline JBF

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Re: We all love patina. Tips for improving a natural patina?
« Reply #5 on: May 27, 2020, 04:02:09 pm »
I know a guy who experimented toning a bronze with gun blueing, he ended up with a blue As (or was it a sestertius?).  It _was_ one of those.

True story.  Every once in awhile it comes up for sale.  Very nice coin, but blue.

Unless you know what you are doing, it is usually best to leave it alone:D  I don't know what your skill set is, but I know that _I_ would be fated to make it worse, rather than make it better.

Offline otlichnik

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Re: We all love patina. Tips for improving a natural patina?
« Reply #6 on: May 27, 2020, 05:54:18 pm »
There is no formula.  Patina is a result of several factors:

- moisture in soil, sometimes this even varies across one object if part was more often wet, this is rare to see in coins but can be seen in larger antiquities

- minerals in the soil, combined with moisture levels,

- proximity to other objects when buried and their metallic content,

- isotopic content of the metal itself, which varies across the coins and metals did not mix perfectly in the ancient world.

SC
SC
(Shawn Caza, Ottawa)

 

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