I found this one in a coin jar, it has the strange silver color like the other pictures posted from the other guy, but mine is the same 19mm diameter as a regular coin, there appears to be no pitting or large strataches, also looks like a poor strike or just some circulation wear on it. It is strange it is the same date although from the denver mint. any ideas? I have closer up photos also.
how do you tell the difference? there appears to be no corrosion marks, Zinc is a much more reactive metal then copper when it comes to acid, so how does one remove the copper plating?
Just like you said, by putting it in acid. That looks like traces of the copper plating on the bottom obverse rim to me. Also, much of the coin's detail is gone - just like it would be if the plating were stripped off.
tired, acetic, hydrocloric, sulfuric, and critic acid, all have not effected the copper plating on a test penny, any ideas??
OK it's Nitric acid that works for copper, but I don't have any of this around, does anyone care to try a test experiment if they have some?
I dont have any pictures on hand, but I have done an expiriment with nitric acid on penneys and got the same result after soaking them for about 10 hours (weak nitric acid).
The only unplated cents you can be sure about are those that retain original mint luster. This is one of the most commonly faked errors out there. Sometimes the copper is plated over. Other times the copper is stripped off (possibly be reverse electroplating). A dull finish, rough surface, fuzzy design, microscopic bumps -- these are all indicators that the coin is not genuine.
Given MikeDiamonds post, is that original luster still around the details? One thing I am curious about with the fakes....I have found a few, obviously acid pitted, and they all have one other trait in common, the edge looks ] shapped (think square U). Why is this? I know with acid dipped clads the copper often is eaten away faster thus the shape. Have others found this to be true?The coin above does not have this trait so I'd guess a different method of removal, or its legit, allbeit worn. Thoughts?
I'd like to relate my experiences with unclad Lincoln's. I have found a couple in pocket change and purchased a couple because they interested me. They have all come back from NGC bodybagged. I didn't believe an acid dip could leave a coin with an uncirculated appearance so I experimented with electrolysis. It takes about 30 or 40 minutes to remove the copper with a trickle charger. It leaves a ring of carbon around the outer edge which is easily removed with a light rubbing of baking soda and leaves a spotless, unclad coin which may have traces of copper around the rim and appears uncirculated. I manufactured a half dozen before my battery charger crapped out and threw them in my junk pile. Needless to say, my interest in unclad Lincolns has waned and I will steer clear of these in the future. :goof:
One good way to verify the authenticity of an unplated cent is to compare it to the unplated surface of a partially plated cent. The latter are seldom faked and will establish a reliable baseline for comparison. The partially plated cent will show a smooth zinc surface with original mint luster.
Might be worth investing in a micrometer so that you can check one of the copper less coins against a original :smile De Orc
I dug out one of my experiments and as indicated by Mike Diamond I guess it lacks proper luster and is probably a little off color. Unfortunately Mike, I don't have any partial plated coins to compare with. My scale is not the most accurate but still gives me 2.5g This one, believe it or not, is slabbed as genuine by PCI and is an obvious acid fake with washed out details and the small bumps of metal in flow lines.
Actually it's H2SO4, Sulfuric Acid, that reacts with copper the best. Sorry the 2 and 4 should really be down a little if using scientific otations. The H2SO4 reacts and creates CuSO4 and the H is given off as a mild gas or with an abundance of O becomes part of the solution. If allowed to evaporate, there is a blue crystaline substance left on the bottom which is used as a vegatation killer. As to the coin if does appear to have been given a bath in such an acid. It is commonly found in auto batteries and many kids do try just that dipping for the fun of it. Since the battery acid is mild it can be a very controlled reaction. The electrolite process is also a lot of fun and if done correctly can produce some strange looking coins. Typical college chem lab items. No extra credit though.
