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Need Help With Silver Spanish Pesetas Turning Green/Blue.

 
 
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Ukraine
2 Posts
 Posted 08/22/2019  10:57 am Show Profile   Bookmark this topic Add lbonhomme to your friends list Get a Link to this Message
Good Afternoon.
Recently a relative gave me a valuable coin collection consisting of silver pesetas (denominations of 1, 2 and 5 Pesetas) which were stored in rolls. Some of these coins were rolled in a special type of paper until this day they remain intact, however, other coins were rolled in newspaper and they are now covered in some greenish-bluish oxide, which diminishes their value and looks absolutely horrible, I'm horrified. The 1 and 2 Pesetas are .835 silver while the 5 Pesetas is .900 silver. I was browsing forums and they all recommended acetone, but acetone didn't work for me. WHAT SHOULD I DO?!!
Valued Member
United States
247 Posts
 Posted 08/22/2019  11:32 am  Show Profile   Bookmark this reply Add Seeker55 to your friends list Get a Link to this Reply
You could try dipping one or two coins in E-Z-Est coin cleaner solution for up to 5 minutes and scrubbing with a toothbrush to see how well this works

https://www.wizardcoinsupply.com/pr...5-ounce.html

This is (by weight) 2% sulfuric acid and 5% thiourea (strong reducing agent) in water.

(Material Safety Data Sheet with formula at https://www.wizardcoinsupply.com/ol...st-MSDS.pdf)

Be aware it will remove any patina on the coin.
Edited by Seeker55
08/22/2019 11:33 am
Pillar of the Community
United States
1470 Posts
 Posted 08/22/2019  11:37 am  Show Profile   Check colonialjohn's eBay Listings Bookmark this reply Add colonialjohn to your friends list Get a Link to this Reply
Actually it may be a situation to do nothing. Obviously if a 90% silver coin is blue/green the trace copper in the coin alloy (i.e., probably ~5%) is the root cause. For many coins its described as rainbow toning which is a PREMIUM! Why not post a picture of this HORRIBLE situation? You may be a BLAST WHITE kind of fellow?

John Lorenzo
Numismatist
United States
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Canada
3069 Posts
 Posted 08/22/2019  12:33 pm  Show Profile   Check Pacificoin's eBay Listings Bookmark this reply Add Pacificoin to your friends list Get a Link to this Reply
Absolutely DO not use EZ est Coin cleaner and a toothbrush !
Numismatic insanity!
Show some pix and do nothing else for the time being .
If it is PVC damage or similar, there are much better ways to deal with this
Than using Coin cleaner and a tooth brush !
Edited by Pacificoin
08/22/2019 6:35 pm
New Member
Ukraine
2 Posts
 Posted 08/22/2019  7:23 pm  Show Profile   Bookmark this reply Add lbonhomme to your friends list Get a Link to this Reply




I also have ones which are worse, also the acetone I used was industrial-grade (apparently the most pure).
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1002 Posts
 Posted 08/22/2019  7:38 pm  Show Profile   Bookmark this reply Add jgenn to your friends list Get a Link to this Reply
Sometimes blue toning looks nice.

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 Posted 08/22/2019  7:42 pm  Show Profile   Bookmark this reply Add jgenn to your friends list Get a Link to this Reply
How long did you leave them in acetone? I have let a few of mine soak for days.
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 Posted 08/22/2019  11:49 pm  Show Profile   Bookmark this reply Add Dorado to your friends list Get a Link to this Reply

Quote:
Sometimes blue toning looks nice.


..

Valued Member
United States
247 Posts
 Posted 08/23/2019  10:49 am  Show Profile   Bookmark this reply Add Seeker55 to your friends list Get a Link to this Reply
It has been said that dipping in E-Z-Est is "numismatic insanity," accompanied by a lot of emojis, but no explanation was given. I will try to provide some explanation.

I would certainly agree that if a coin has significant numismatic value and/or an attractive patina it should not be dipped in E-Z-Est. I would also say that coin cleaning methods have often been misused and have damaged the values of many coins.

However, when used appropriately, in the right circumstances, some conservation methods to remove contaminants can occasionally be helpful.

First of all let me say that I have a Ph.D. in chemistry and some experience in removing contaminants from metals, and can say that in my opinion it is unlikely that acetone will remove an appreciable amount of the green encrustation. Acetone is good at removing organic (carbon-containing) contaminants such as PVC or tape residue. The encrustations on your coins are inorganic, possibly copper chlorides based on the color, maybe some sulfides, oxides, and hydroxides, and these types of compounds aren't soluble in acetone.

These coins are worn and the surfaces have already been damaged by the green encrustations. I doubt that they are worth much more than melt value in their present condition.

There are several ways to remove the encrustations, but they might not increase the value of your coins. It may well be best to leave them alone and not spend your time trying any of these.

However, it is my understanding that you'd like to know your options on how to remove the encrustations. So far I have not seen any methods proposed in this thread other than E-Z-Est that have a reasonable chance of removing the encrustations, and I will give some other options below.

For coins that have primarily bullion value, the appearance, but not necessarily the value, can sometimes be improved by several other methods.

1. Soaking for a couple of weeks in a solution of sodium sesquicarbonate (this is a treatment for "bronze disease" consisting of 16.8 grams sodium carbonate plus 8.4 grams sodium bicarbonate in 100 mL of distilled water).

2. Tumbling with a very mild abrasive medium such as crushed walnut shells

3. Mild electrolysis

There are risks to the coin surfaces in all these methods. If you wanted to try any method I would try it out on a single coin of low value. Incidentally, a patina on a silver coin can be regained, though it might take many years.
Edited by Seeker55
08/23/2019 4:29 pm
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United States
2460 Posts
 Posted 08/24/2019  08:55 am  Show Profile   Bookmark this reply Add tdziemia to your friends list Get a Link to this Reply
Very good post.

We don't know the OP's goals, and we have only seen one example of what are presumably dozens or hundreds of coins.

If there are many coins in the kind of condition shown (circulated and corroded), and the goal is to make the coins more presentable for sale on eBay, the experiments proposed sound reasonable.

The poster should be aware that some potential buyers/collectors will see a perfectly white surface on an old circulated coin as a strong negative, but for lower grade coins being sold on eBay, corrosion like this is the kiss of death.

It would be interesting to see an example of the coins that were stored in paper rolls rather than newspaper.
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