Coin Cleaning - A Successful, Yet Controversial, Example

Carl: I appreciate the chemical explanation. I cannot disagree with you on any point you made. You're absolutely correct. I'd much rather be left with an extremely minute amount of metal missing than a big ugly green splotch. I have to say though, at 10X I'm not seeing any problems with the surfaces of these coins. It's possible at 20X you might see where the metal was disturbed by the removal of that crud. For all practical purposes...at this point (and I have no intention of selling these any time in the near future)...the coins are "market acceptable". There's nothing a dealer would find under any normal power they would be carrying with them to indicate any issues. I'm not saying that anything is hidden or attempted to be hidden; the coin surfaces have definitely improved. I will be curious to see these coins within a year to ensure that nothing strange occurred as a result. I'm fairly confident that they will come out fine, but I'll report either way (if I remember...LOL). I'm not trying to pull a fast one on anyone. Whenever I sell anything, I give full disclosure about a coin and if there are any problems and always give a full refund without hesitation. I don't believe in trying to hurt anyone in a deal.

Thank you "chrsb". I think what you're highlighting is that perhaps the pendulum is being swung too far the other way. Yes, it's good to be paranoid about cleaning coins, but it's absurd to leave them as worthless chunks of metal if there are suitable techniques for improving them without short- or longterm harm.

Does anyone really know for sure how Numismatic Conservation Services (NCS) may remove the green crud from a copper coin? Or even if they do?

I can't imagine too many other special "potions" that aren't already in general use such as acetone and alcohol.

Found this on NCS board under the verdigris. all below is straight off the post.

"What is called verdigris is often caused by several different things.

Some green encrustation on a copper coin is protecting the surface of the coin. Although this could be removed, it will leave the coin vunerable to further deterioration quickly. When the encrustation appears to be of this type, NCS conservators will most likely not remove the encrustion.

Other green on copper coins is corrosion which can and should be removed. The coin will be more stable in the long-term and more attractive as well. Usually the coin will still be deemed "corroded" by a major third party grading service such as NGC in this case.

Other green can be PVC residue. This can usually be removed safely. Assuming the PVC has not begun to eat into the surface of the coin and it does not have other irreversible surface problems, the coin should be gradeable by a third party grading service.

Chris, NCS"

To each there own, clean away if you must.

What NCS says is completely true. They, however, kept out the technical explanations knowing most would not understand. When a grading service checks out copper coins they attempt to evaluate if any green patina is from normal Oxydation as I discribed earlier. This is what they indicate as something that is normally not removed. If, however, the greenish substance turns out to be a Cupric Sulfating substance that could continue errosion through chemical compounding, it should be removed to stop continuation of errosion. Such coins should be protected from whatever created such contaminations though. As to PVC contaminations, it is not PVC that creats problems with coins. PVC itself is a stable Organic compound, melting point of 212F degrees but is rather stiff so chemicals are added to make them softer. This substance, Phthalates, tend to leak out over a period of time. Naturally after a while there is very little left to contaminate anything so if the PVC has become rather stiff, most of the Phthalates have leaked off indicating the PVC is not completely harmless. Please note in many areas your household water supplies are in PVC piping. Therefore the PVC scare of coin damage is usually exagerated.
However, as noted it takes experts to determine what is to be removed and what is not on coins. But if the coins are not of any value, it really doesn't matter anyway.
I too have cleaned many, many coins and must admit as long as they are not for sale, they do look nice.

Prethen,

I like the new title change you made, as some new collectors can see why cleaning a coin can be very subjective.

prethan you did an exceptional job with this copper coin

it turned out well and by doing this properly you not only removed the pvc and other gunk from the coin you left the surfaces intact

not really cleaning per say and yes every coin is different and some might not turn out like this

but........

this time you did well and saved a coin kind of like washing your car off of all the corrosive salt and you did not leave any hairlines or scratches on the paint job in other words you left the original surfaces for the most part intact and this coin will still grade at the top tier services or in other words I would be proud to add this coin to my collection

with coins it is different with every scenerio some work out and some do not it is all a guesstimate and experience

this time prethen it worked out and you did well


there are no sure things or absolutes in coins, coin buying, coin grading just experience and making the best choice out of a few options ........................