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What is this stuff?


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Olive oil will do nothing for it...verdigris is a copper salt like rust. It is usually copper acetate or a copper hydroxide. Neither of these would come off with any kind of oil. The copper salts will flake off with with a little soak in water and rubbing so in this case...oil is just as good as water.


Some forms are soluble in water so it might be possible to use hot water and rub them with your thumb to remove some of it. If the verdigris is light, wiping with vinegar may remove it. Follow it with a distilled water rinse. Sad thing is, removing heavy verdigris will expose pits from the corrosion. Your doesnt look very heavy.


An acid dip can be made easily from salt and ammonia mixed together. If you do this be very careful and use gloves. Dip the coin for a short period then rinse with distilled water.


You might want to try it first on inexpensive coins until you have got it right. But first just try to soak it in distilled water and rub it off...that might be all you need to do.

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Do NOT use Vinegar. It contains about 4% Acetic Acid. Do NOT use any kind of Acid at all. That green stuff is NOT Verdigris which in itself is usually caused by Copper coing in contact with an Acetic Acid. That is why when you did try it you made it worse, not better. Also, before someone blurts in with PCV, it is not PVC.

What you have on that coin is called normal Oxydation and it is difficult to remove because it is now part of the coin itself. You could try the Acetone method for dipping Copper but that also usually does not work. The best thing to do is VERY gently rub the coin with a baking soda and distilled water mixture. VERY GENTLY. This will neutralize the Oxydation process to some extent but as I mentioned what comes off is part of the coin. By rinsing with the baking soda solution you would cause the least damage. After that rinse with distilled water and blot dry with a piece of cotton. Whatever is left is best left alone.

ALL Copper Oxydizes in normal atmopheric conditions and pending on the atmospher some places Oxidize faster. First you get Cu20. It will now be a brownish color which is normal. However, now the normal reaction of moisture (H OH) in the air along with Carbon Dioxide (CO2) attacks the Cu2O to form Copper Carbonate [CuCO3-Cu(OH)2] which is the greenish patina now on your coin. This is even worse in some areas where Sulfur burning coal is used and SO or SO2 is present in the air. This Sulfur Oxide mixes with the moisture in the air and further attacks Copper compounds. Even more of a greenish substance.

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A jackhammer may work.

AHHH, yes but what solution would you put on the coin so the jackhammer will only hit the green stuff?

Also, if you put the coin against a tree, fire a .22 at it, you'll notice the green stuff may well vanish.

However, remember to stand far enough away so the gun powder dose not hit the coin. Gunpowder is composed of Sulfur, Charcoal and Potasium Nitrate.

VASOLINE? Who ever told you to try that? Now you have a coating of that on the coin and who knows what will happen next. If you can, go to Walmart, go to paint department, look where they have cans of paint thinner and look for and buy Acetone. Put some on a glass plate, soak your coin in it, remove and rinse with distilled water, blot dry with a soft towel, no more rubbing please.

The Acetone will remove the haze left from the Vasoline. I hope there is still a coin left when you finish everything.

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looks like verdigris to me :ninja: and yes, vinegar is probably not a good idea, that was a mistake...my bad. I have used amonia and salt on verdigris with good result...mix the 2 and dip briefly...rub lightly and dip in water...regardless...if it IS verdigris and if you dont stop it, it will destroy the coin completely. I will give you the advice I got:


"removal and prevention of further encroachment may be possible with careful use of acetone or a neutral coin solvent such as MS67, followed by neutralization with chemically pure alcohol or distilled water, without rubbing dry. Beware of “pure” alcohol sold In chain drug stores; fine print often reveals added emollients.


One problem with removal even of an apparently thin presence of verdigris is that it will open a hidden, ugly pit in the surface of the copper beneath. Thick encrustations are liable to reveal serious gaps in the integrity of the metal."



More advice from guys who clean ancients:


"The verdigris isn't actually an oxide - if he has any black stuff on there (usually forms before the green) then that's the oxide. The green is a combination of two basic sulphates, brochantite, CuSO4.3Cu(OH)2 and antlerite, CuSO4.2Cu(OH)2. These are bonded to the copper with atmospheric organics. There are a few ways to get it off, but the best way is probably to use acetone or maybe metho - it dissolves the organics and gets the verdigris off, and is nice and and gentle on the copper. A weak acid should also work (reacts with the basic sulphate), but isn't as gentle on the copper."


Copper(II) acetate is soluble in alcohol and water and slightly soluble in ether and glycerol. It melts at 115 °C and decomposes at 240 °C.





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Also...as an ancient coin cleaner myself..I CAN say that if indeed that is just patina forming on the coin...vinegar and salt WILL take it off...I have done this on old crappy slugs in the vain hope removing a patina might expose detail. It will require scrubbing though...electrolysis will take off patina as well... I should probably just shut up :ninja:

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CuSO4????? A BASIC Sulfate? WOW wonder where those coins have been. Must be in a Acid factory. Even in areas of strong Sulfur Oxides in the air the amount that actually mixes and becomes known as Acid RAin is to minor to cause reactions with bare Copper. The Copper must already be Oxydized. One more time Verdigris is basically Cu(OH)2-H2O and is usually caused by contact with an Acetic Acid or compound containing such. If contact is excessive should become Cu(CH3COO)2-H2O.

Meanwhile back to your coin. Please stop doing anymore experiments to it. If you listen very carefully you'll probably hear that coin crying.

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