I just started a new thread here under "General Discussion" called "Proper dipping of a Peace Dollar" and ask for responses to the question. Lets give it some time and see what happens.
I cleaned the crude off of one that looked much like that. I used MS70 and a Q-tip. The surfaces were mark free and there was still some luster visible so I included it in a batch of coins going in to get graded. Now the coin was still gray and looked weird as heck but PCGS gave it a 64 anyway. I was just curious what they would do with such a cleaned coin.
I have found MS-70 to be a miracle product. I just turned four dull CWT (that a man was offered $14 each at the Brandon show by a well known FL token dealer) into two lustrous brown MS-63's and two MS-64's in less than ten minutes. MS-70 was part of the treatment. Now the pieces should sell for over $100 @ I imagine. The next time I get a scuzzy copper coin in I'll do a before and after post to show the doubters!
I believe the coins are unavailable. I will see. However, you have changed the subject. I'm talking about MS-70 turning a dull, brown, choice AU'ish looking CWT into a Choice Uncirculated coin. If you were following my posts - on another thread I revealed how a dealer I taught was regularly getting a particular series of copper slabbed as 65's with just a little conservation as I have written about above. As I said, I will post some before and after's. In the meantime I'll suggest you all get some MS-70 and learn to use it properly! Now close your eyes and imagine a CWT with no trace of wear (perhaps just a little darkening on the high points) and virtually no contact marks. The surface of the fields is iridescent brown with a trace of lavender at the rims. BOOM! Mint State. No tricks, just removed the dirt and film from a nice coin to begin with.
Notice my CT Handle note. CWTs are my specialty. MS-70 is good, but its amonia can remove patina, if not used sparingly. Coin Care rules as a conservation product.
MS-70 sounds heavy duty, has anyone used it diluted compared to straight up at all using on an old test type coin to compare one area of the coin to another to see the contrast from one point to another ?
I use full strength and it will often lighten the surface a little but another trick will get it back to normal - BUT Blast clean. If acetone is used after the 70, the coin may turn blue. So MS-70 needs to be removed from the coin with HOT, SOAPY water. WARNING: If a copper coin has any "red spots" (NOT mint red luster) from corrosion products the MS-70 will make them stand out which is not desirable! You'll need to work around them or conserve the coin another way.
Sounds like you 'teach' or are a Conservation specialist. How about a link to this thread about conservation.
I'm thinking I'm going to keep this Peace the way it is because of the sharp details under this dark tone. But would love to get an old nappy looking crud coin the use it as a test piece.
I feel like we are playing "What's My Line." For you younger members, a blindfolded panel tried to guess the ID/profession of a famous guest by asking questions. A long time ago I worked part time for a token & medal dealer. Unc CWT were about $5. I learned a few things. I like to clean stuff so I've been at it for about fifty years. I'm not a chemist. I'm not a specialist of anything and a dunce at most. I have taught different subjects related to coins on occasion. I once posted on CT that I did show a FL dealer some of my methods and he has done very well for himself. I've ended up with some counterfeit gold for my collection that he was going to melt and jewelry for my wife. He is a very generous person. Now the bad news...tricks of the trade are a give and take thing with me. If not done correctly, you can ruin a coin. I believe my friend Brian Silliman teaches a conservation class for the ANA. He worked at NCS at one time. He has signed confidentiality agreements so he too cannot divulge all he knows. There is plenty of info on the Internet. I feel I've already said too much about the use of MS-70 here as it is.
Follow-up, Follow-up. I sent it in and got it back graded at MS61. Not bad fo r a piece I was not sure would grade, even though it was ANACS.