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FORVM`s Classical Numismatics Discussion Board  |  Uncleaned Ancient Coins  |  Uncleaned Ancient Coin Discussion (Moderator: bruce61813)  |  Topic: Cleaning Chinese cash coins 0 Members and 1 Guest are viewing this topic. « previous next »
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otlichnik
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« on: February 14, 2010, 09:36:55 am »

I thought I would post a few images of Chinese cash coins in the process of being cleaned.

Like ancient Roman and Greek coins the patina on Chinese cash coins is important and can add substantially to the value.  Chinese collectors in particular can greatly value the esthetic qualities of the various colour combinations - cash patinas can include colours seldom seen in western ancients such as blue, red, orange and purple.

However, it is also more common to find Chinese cash that have been chemically cleaned, often done to a very high standard, revealing the original metal.  And interestingly, this is not considered by many to be as heinous a "crime" as it is with say Roman coins.

It is also very common to find Chinese cash where the raised surfaces - the calligraphy characters and the rims - are cleaned, sometimes even to shiny metal, while the fields still have a patina or even a thick crust.

As such, in many loads of bulk Chinese cash few if any coins require much cleaning beyond a nylon brushing or picking the dirt out of the characters.

However, sometimes you encounter real "crusties" among the bulk coins and this can be very exciting as they are truely unsorted - they can not be identified until cleaned.  These coins have a very hard, but usually smooth, crust on them.  It can be quite thick.

Most websites I have seen that address cleaning Chinese cash recommend chemical cleaning.  However, being primarily a cleaner of LRBCs, I like to attack them mechanically.

Scalpel/x-acto knife is of some use but may main weapon is the steel pin - usually a sewing needle - which I keep sharp with a whetstone.

Below is a before picture of four Northern Sung Dynasty (my guess based on fabric and rest of the bulk lot) Chinese cash.  Note the very thick, hard patina.


 
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(Shawn Caza, Vienna)
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« Reply #1 on: February 14, 2010, 09:41:30 am »

In this next photo I have used the pin/needle on approximately 50% of the surface of each of the same four coins.  This represents only an initial round of work on each coin.  Approximately 5-7 minutes per coin.

The needle was sharp, the angle very low (almost parallel with the coin's surface) but the pressure required is very hard.  This work is rough on the wrists.

The encrustations will flake away.  Sometimes in very large chunks.

You can see small and large flakes lying around.  You can also see the brown-ish patina of the coins exposed.

Shawn
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(Shawn Caza, Vienna)
otlichnik
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« Reply #2 on: February 14, 2010, 09:53:04 am »

In this image you can see the two right hand side coins from the previous images.

I have used the pin/needle on the entire surface of the two coins.  I also went back over the entire coin with a small pin to work more carefully on the characters.

The area around the bottom character of the lower coin looks odd.  It has a casting flaw where the copper at the rim and lower part of this character are raised very thick.  This makes the area look shiny with the side lighting I used.

I plan to leave these two coins as is now.  Not only can the basic type be identified but even the Gorny variation.

I could easily get more of the encrustation off, particularly around the characters, but it is still hard and the force required makes working in those areas too risky - too much chance of scratches.

Besides, personally I like the constrast offered by the green.

I spent roughly 20-30 minutes per coin.  I know that in terms of time versus value that might be considered a waste.  I could have bought versions as nice as I ended up with or even better for under $5 each.  However, it is my hobby and not my investment and I am quite happy with my results.

Shawn


 
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(Shawn Caza, Vienna)
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« Reply #3 on: February 14, 2010, 09:56:55 am »

I forgot to mention that this technique has only worked on around 50% of the Chinese cash crusties.  The other 50% have proven too hard to get almost anything off.

The coin below, though hard to see in this photo, has revealed a very interesting purple-grey patina.  I am cleaning it much more slowly.

Shawn
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(Shawn Caza, Vienna)
larry c
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« Reply #4 on: February 14, 2010, 10:12:59 am »

Excellent topic Shawn, I also have been working on uncleaned Cash Coins
And have wondered why we never see any post in the unclean section on them.
There seems to be very little info on the web with the exception as you stated of bulk chemical cleaning by acid bath!!

Any other cleaners out there working on Chinese Cast Coins?

The two pics below are a half Kilo of fused Wu Zhu and one that I have cleaned Mechanically.
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Matthew W2
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« Reply #5 on: February 14, 2010, 12:57:48 pm »

This is really interesting. I have a couple of these old Chinese coins, but have never "gotten" the appeal of collecting them. Largely I think due to my own ignorance of the variations.

Is there a good place to go to learn more?

How would you define a set of what to collect?
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Tiberiusjulius
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« Reply #6 on: February 14, 2010, 03:01:06 pm »

Not sure if this has been mentioned but a guy at a coin show told me that he used the in a plastic bag in dryer method to clean cash coins like Larry C's examples.
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crawforde
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« Reply #7 on: February 14, 2010, 03:13:27 pm »

great topic,
I have a very similar 1/2 kilo of fused Wu Zhu coins and have had some luck separating and cleaning them.  
My first step is to put the coins in a mesh "dive" bag, put it on the grass, and spray it with the hose under high pressure.  This gets most of the dust and loose soil off as well as separating the loosest chunks (caution at this step, a few coins have broken).  Next is soaking in distilled water for a couple of weeks with regular water changes.  
The next step I use is to drain off most of the water and subject them to numerous freeze thaw cycles.  This separates many of the coins and also flakes off some more soil.  I have been left with some beautiful blue and turquoise patinas.
I also have some Kai yuans that were not as bad and they are cleaning up nicely with soaking, picking with some skewers and brushing.
I will try to get some pics.
Do any of you oil, wax, or stabilize in any way?  I have on some coins, and not on others, but haven't been doing this long enough to see any difference.
Also, what do you do with the iron coins?  I have been tempted to just acid wash some real crusties , but  am pretty sure not much will be left if I do.
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crawforde
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« Reply #8 on: February 14, 2010, 03:17:54 pm »

I wonder if Joe would sponsor a Chinese Uncleaned competition here?
If he is game, and there is interest I would be willing to donate some coins to help get the first round  going.
That might increase the Chinese Cash coin collecting exposure here, we are underrepresented  Smiley.
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Matthew W2
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« Reply #9 on: February 14, 2010, 03:50:55 pm »

To answer my own question a bit, a little poking on google uncovered this:

http://coins.calkinsc.com/old_site/doc/chinesecash.html

There certainly seems to be more to them than I ever realized.
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larry c
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« Reply #10 on: February 14, 2010, 05:47:07 pm »

Not sure if this has been mentioned but a guy at a coin show told me that he used the in a plastic bag in dryer method to clean cash coins like Larry C's examples.
What I meant by mechanically was cleaned under a microscope
using picks & probes to pick off the corrosion.
My favorite tool is a dull bladed rounded  xacto knife to work the crust
away!
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larry c
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« Reply #11 on: February 14, 2010, 05:54:01 pm »

I wonder if Joe would sponsor a Chinese Uncleaned competition here?
If he is game, and there is interest I would be willing to donate some coins to help get the first round  going.
That might increase the Chinese Cash coin collecting exposure here, we are underrepresented  Smiley.
That's an idea. I have quiet a collection of crusties waiting their turn.
Maybe get more input on cleaning skills & tips.
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Tiberiusjulius
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« Reply #12 on: February 14, 2010, 06:47:07 pm »

Not sure if this has been mentioned but a guy at a coin show told me that he used the in a plastic bag in dryer method to clean cash coins like Larry C's examples.
What I meant by mechanically was cleaned under a microscope
using picks & probes to pick off the corrosion.
My favorite tool is a dull bladed rounded  xacto knife to work the crust
away!
No, I knew what you meant by cleaning , just referring to your picture.
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otlichnik
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« Reply #13 on: February 15, 2010, 06:41:46 am »

Matthew W2,

A couple of comments.

First on where to learn more.  There is a good deal of info buried in the "Other Types of Ancient Coins" heading of this forum.  There is another forum called zeno.ru.  It has may images of Chinese cash but is not organized in a way that makes it good for the novice who wants to learn more.

There is an excellent informational site from a dealer of coins in Calgary at http://www.calgarycoin.com/reference/china/china.htm

The best overall book on Chinese coins in English is David Hartill's Cast Chinese Coins.

You can then go into greater detail on minor variations through other books - Norman Gorny's series on orthern Song cash and some articles by Thierry in French on Wu Zhus and Kai Yuans.

As for what to collect, it is the same as with Roman.  There are any number of options.  Many people try to collec coins from each emperor.  In addition many emperors issued coins in several "reign titles" thus there may be 2-4 types per emperor.  At the other end of the spectrum some people will collect only one coin type.  The Wu Zhu was used from 118 BC to AD 617.  There is a lifetime of variations in this coin alone.

Shawn
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Matthew W2
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« Reply #14 on: February 15, 2010, 03:27:16 pm »

Interesting! thanks for the links!

What I like most about collecting coins is the knowledge about other times/places/cultures. It's much harder to appreciate the fine points without knowing anything,
and the more you know the finer the points get Smiley

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Stkp
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« Reply #15 on: February 15, 2010, 09:33:13 pm »

Here is Norman F. Gorny's post on cleaning cash coins. 

http://oriental-cash.blogspot.com/2009/09/care-for-your-cash.html
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Belisarius
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« Reply #16 on: July 21, 2011, 03:44:42 am »

Do you have any links where uncleaned coins can be bought?

Belisarius
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