Cleaned Coins

jaobler

I am sorry
my speciality is gold grading
the coin is painfull on my eyes so I hope a connoiseur will
answer your question

Hi Therisker,
Your questions are excellent. Cleaned coins still give me trouble, although I'm gradually getting better at spotting them. I still get fooled sometimes.
The half dollar posted by AnemicOak is not that hard to spot as cleaned. This coin has virtually Mint State details with no visible wear to my eye. As such, it should have some original mint luster which should show as bright areas and darker areas in the photo. These "hot" and "cool" areas are created by light reflecting off the microscopic flow lines that are created in a coin's surface when it is struck. Their position on the coin will change if the position of the light source changes. You can easily see this effect on any modern BU coin. Take a new quarter, for example, and tilt it under a light. You will see the hot and cool areas move across the coin as you change the angle.
AnemicOak's half dollar has a washed-out, uniform dull appearance, especially on the obverse. There are no hot or cool areas. I assume it was "dipped" in a tarnish remover like a thiourea solution in an attempt to remove stains or oxidation. This treatment got rid of the tarnish but in the process the original luster was damaged.
"Dipping" is one type of cleaning which may not hurt a coin too badly if it is done carefully. In this case I imagine the coin was in the solution too long and it has definitely lost both luster and value as a result.
The other kind of cleaning is "abrasive" cleaning which physically damages the coin, usually leaving hairline scratches. I was finally able to copy the following image of the PCGS AU50 slabbed 1874 half dollar that I mentioned in a previous post. There are fine scratches over the entire obverse. The scratches are mostly parallel which probably indicates the coin has been wiped with an abrasive cloth. Any coin that looks like this screams "CLEANED" to me. As such, I am very surprised it was slabbed by PCGS. Somebody bought this coin for over $400, which is close to retail price for an original (un-cleaned) AU. I think they paid too much.
All this is just my opinion, of course, based on what I've learned from more knowledgeable collectors and trusted dealers.

I've seen posts regarding cleaning with acetone, lemon juice, tin foil in water with baking soda, etc. Is there a definitive way of cleaning coins acceptably?

I have mostly Lincoln cents, Indian Head cents, & Mercury dimes. I bought a set of Uncirculated Lincoln cents 1954-2007. Some of the earlier coins had black stains, but they appeared Uncirculated. Some of the Indians have an adhesive on the reverse. Most of the Mercury dimes appear "dirty" with grime.

What methods have people used to safely clean copper & silver, but are not considered "cleaning?"

Top Advice for cleaned coins.
Fine Lines can be seen under a microscope...

So..could anyone tell me how to clean the coin in acetone? Can you clean all types of metals? To you let the coin Air dry after or pat it down?

Thanks,

Snookless

A very interesting topic with great visual aids