24 Aug 2014

i would like advice on how to Identify cleaned coins


Hello fellow Numismatists,

When I purchase nicer looking high grade coins, I am always suspect of whether or not if it was cleaned via dip, or just a gorgeous specimen. How do I tell the difference between mint luster and a dipped cleaned coin?



Level 5

Pretty awesome Kurt! Zee Gato as you say, eez, yes out of zee bag. If NGC and PCGS accepted it, it is good enough for me. I will do some more reading on how to recognize a coin cleaned by harsher means. When I was 12...I used a pencil eraser. I never had much worth anything back then as far as what I SHINED up so No 1909-S vdb were harmed. but back then it wasn't common knowledge that cleaning them was a bad thing. In fact I got that advice from dealer my grandma took me to.(we're talking 1976 here). So I erased the tarnish, but erased the value along with all of my wheat pennies. I see a lot of gorgeous washington quarters on ebay that are brilliantly shiny. Some are obvious they've been cleaned when they are worn right down but shiny as new, some are not so obvious. Thanks for the tips 9998 and Kurt. Cerg


Level 5

Pay attention to any odd toning, coloring, tarnish, etc. This is usually a sign of cleaning. If a coin appears overly or suspiciously shiny, this is another sign. I am not an expert on this, so there is plenty more to hear, which will hopefully be provided by more experienced collectors, but I hope this is helpful!


Level 4

I paragraphed that response to death, and the software stripped it all out. HONEST!


Level 4

This is all just my personal opinion and many here may, and probably do, disagree with me. That said, here goes: Any silver coin older than the Great Depression, if it has never been at least dipped somewhere in its past, will exhibit some toning. Too many early storage media had high sulfur content, and sulfur is the natural enemy of bright shiny silver. Even World War II era coins, if undipped and brilliant on their two sides, will exhibit edge toning from having been in an original roll for decades. Now, here comes the controversial part of my response: not all dipping is the same, and most of the hobby sees an important distinction between a light chemical dip and true mechanical "cleaning", which implies some measure of physical "scrubbing", for lack of a better term. Now here is the new self-promoting REALLY controversial part: At ANA Rosemont a few weeks ago, I gave a Money Talk in which I revealed a chemical dip from an old Eastman Kodak Company publication that was used to remove silver sulfide stains from clothing and towels used in old-school traditional black & white printing darkrooms. It uses thiourea and citric acid, and my 10 years of using the dip myself has proven to me that it is 100 times more gentle and non-damaging to delicate coin surfaces than any commercial coin dip on the numismatic market. I have personally used it on proof coins from the 1950's and business strike coins of even older date and those coins have passed BOTH NGC and PCGS grading without so much as a hiccup. And those buggers are really picky! I have had hugely ugly brown and black toned silver dollars grade MS65+ even AFTER using what I affectionately call Kodak dip on them. If you are curious about this formula, Google "Kodak Stain Remover S-10" and plan on scaling down the recipe to less than the GALLON (!!!!) size of the original formula, and plan on probably doing some unit size translations. This dip is so gentle on coin surfaces that it is possible to alter the strength and pH of it to change the rate of tonal change, and by raising the pH enough (with baking soda), even REVERSE the process completely, to ADD toning to silver, rather than remove it. I am KEENLY aware that what you read here is NOT in the knowledge bank of the mainstream of numismatic science. I only am aware of it because of my past career in photo lab work. Anyone who tells you this information is bogus is, I'm sorry, but just WRONG. I have done it, and as of August 9, 2014 at 9AM, it is within the information provided at an actual ANA "Worlds Fair of Money" Money Talk presentation, so zee pussy gato, she ees out of zee bag, no? Proper dipping of a coin with Kodak S-10 need NOT damage original mint luster, as "regular" dipping admittedly does! How's THAT for a bombshell?

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