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 Replies: 25 / Views: 3,016 |
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Bedrock of the Community
United States
10635 Posts |
Coinfrog knows the science involving coins more than you will ever hope to know. Please do not disrespect our members, especially the Bedrocks of our community, and we will not disrespect you. Members here have tried to help you, but you don't seem to be willing to listen. I agree with the assessments that have been made here that your coin *looks* to have a spot of glue on it OR perhaps was struck through a piece of string or some other fibre when minted.
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Valued Member
United States
171 Posts |
@BakedPotato, if you read the 2nd sentence of your link: Quote:
This reaction does not occur in the absence of light.
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New Member
 United States
23 Posts |
I'm not trying to be rude. it doesn't seem right to give advice to do something that could potentially make coin lose value to find out if it has value.
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New Member
United States
23 Posts |
Listen I have much respect for coin frog and everyone else I'm not trying to claim I know more then anybody in fact I probably know less then most people. I just think I should to have someone who knows coins look at and tell me what they think before I go putting chemicals on it
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Pillar of the Community
United States
1667 Posts |
Well there were some opinions and a recommendation to get to the bottom of it. So question was answered. If you don't like the answers or a recommendation, send it in for grading and error authentication with your guess, pay the money and see what the expert professionals say it is. One thing is for sure whatever answer you get here is going to be wrong to you unless it's the one you want to hear. It's why you came here after the first place you went, because you didn't like the answers.
And my answer. I believe it's staining and scratching from sitting in a lucky penny holder, damage from coin encasement.
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New Member
United States
23 Posts |
Im all good with answer. I'm guessing you all are probably right. I will let you know what happens with it. My plan is I have a guy at a coinshop who I trust. if he says send It in, I will
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Pillar of the Community
 United States
5785 Posts |
To my friends on CCF, Bakedpotato could have chosen his words differently in responding to CoinFrog but after reading the information at the link he provided ("Photochemical Breakdown of Acetone on Copper" conducted at Stony Brook University of New York from 2005) I can understand his apprehension in using acetone. I am a firm believer in science.
To quote from the study:
"X-ray Photoelectron Spectroscopy studies have shown that acetone, when used as a cleaning agent for copper in the presence of ambient light and water vapor, slowly reacts to form acetic acid. Over a period of 18 hours the copper foil that was immersed in acetone and exposed to ambient light developed blue crystal deposits as shown in the optical photomicrograph in Fig. 1(left)."
It goes on to say:
"Acetone should not be recommended for degreasing or cleaning of copper or copper bearing alloys containing discrete copper rich intermetallic particles. Though ASTM E1078-97 "Standard Guide for Specimen Preparation and Mounting in Surface Analysis" recommends that prior to surface analysis samples should be ultrasonically degreased in analytical grade acetone and isopropanol, based on this work acetone is not recommended to be used for degreasing copper or copper containing alloys. Also one of the other studies performed in this lab has shown that isopropanol has no such effects on copper, and hence we recommend the use of isopropanol alone for degreasing."
And yes, the study referenced left the copper foil immersed overnight (18 hrs) but it still raises the question in my mind about caring for my "babies".
I have always used pure acetone for soaking them for much shorter periods and I don't usually rinse with H2O since it is slightly acidic. My plan is to be more cautious going forward.
I do plan to compare alcohol and acetone on some less than perfect uncirculated mean-agers ... uh, I mean "teenagers" of mine to see if the alcohol removes the original mint packaged grease that often gets on some wheats.
Words of encouragement are one of the major food groups.
We need to consume them regularly to thrive and grow.
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Pillar of the Community
United States
5785 Posts |
As to BP's coin, the OP said PSD was ruled out. Why or what brought you to this conclusion? (It is the usual culprit.) IMHO it has the appearance of struck through some "debris" which flaked away or more likely it is caused by some caustic substance (like Chase007 said) that was deposited at the perimeter of the amoeba-like shape. Water on the surface of a coin will often show up in this shape. If it was struck through a string or "debris" it seems like the incuse area would be on both ends, up on the rims as well. Words of encouragement are one of the major food groups.
We need to consume them regularly to thrive and grow.
Edited by Petespockets55
04/27/2020 07:44 am
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Pillar of the Community
United States
2738 Posts |
It appears that this part of the coin was etched by a piece of thread that was saturated with corrosive liquid or coated with a corrosive substance. In other words, not an error.
Error coin writer and researcher.
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Pillar of the Community
United States
574 Posts |
In reviewing the study referenced by the OP, it's important to note a few key items:
1. The authors allowed the copper foil to sit in a beaker of acetone while the acetone evaporated, causing crystals of acetic acid to deposit onto the foil.
Avoid evaporation of the acetone and you should avoid deposition of crystals.
2. Since the sample not exposed to ambient light suffered no adverse effects, clearly acetone alone is not a problem for your copper coins, even if you grant the validity of the rest of their conclusions.
3. The ingredients for the chemical reaction they described were acetone, copper, ambient light and water vapor. The water vapor was introduced into the reaction from ambient air (since the acetone evaporated there could have been no lid on the beaker). Thus, using a lidded container limits the exposure to water vapor and prevents or significantly limits the described reaction.
4. Better chemical minds will have to answer, but is acetic acid soluble in acetone? If so, a rinse in fresh acetone should solve the problem. Is it soluble in water? Same answer.
5. The study is almost 20 years old and cites an ASTM standard that is no longer in use. Further, the ASTM standard relates to preparation of samples for micrographic study so essentially this study is saying that if you use acetone on a copper sample, in order to clean it, that you intend to study under super magnification, and then allow the acetone to evaporate it could leave acetic acid crystals on your sample surface, because of a chemical reaction involving ambient light, acetone, copper and water vapor, thereby skewing your results.
I respect everyone's opinions on whether or not coins should be cleaned, conserved or whatever else you want to call it, but I don't think this study does anything to suggest that reasonable acetone use presents any risk of harm to your copper coins.
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Replies: 25 / Views: 3,016 |
First Page
Posted 04/27/2020 02:20 am
