Is using pure acetone considered"cleaning"?

I had a small red dot on one of my gold Panda's and a dealer dipped it for me before sending it off for grading. It worked well in my estimation but I would not do this myself. That's why I let a pro dip it.

 

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Look man, you're making some claims. I'm asking for evidence or proof; you're blowing me off. Don't turn this back on me. You do this often when people challenge you.

Until I see proof, evidence, photographs, or something more than someone claiming that they saw it, I'm going to keep challenging you.

There are many, many copper coins designated as questionable color, for a wide variety of reasons. You say that you have seen this before - describe what colors you saw. You said it was "weird." Describe the look that these coins had.

I'm asking for are more specifics than the general hand-waving obfuscation that you are producing.

I can tell you exactly what look I expect from a copper coin treated with MS-70, and link to numerous threads and photographs. Why can't you explain to me what I should see on an acetone-treated copper?

I could tell you that I've seen bigfoot. Would you believe me? No, absolutely not.

However, if I showed you clear pictures of bigfoot, would you believe me? More people would be more likely to.

If I brought you a sample of bigfoot's hair, and characterized bigfoot in a scientific manner, would you then believe me? Yes, even you might then believe me.

I'm asking for evidence, proof, a description. Something more than "I say that I saw it, and so you must believe me." Sorry, Doug, that's not good enough - not from you, not from anyone. I'd question Q Dave Bowers himself if he made a claim like that.

If I knew what I was looking at, or looking for, I would certainly have more basis for hypothesis.

Yes, it absolutely matters! I take pride in sharing accurate, verifiable, provable information. If I make a claim that something is going to affect someone's coin, I need to know that information is correct!

I really don't understand how you could even question that.

 

I know it is only the abstract, but I believe that should be enough to understand the gist of the paper (as well as its application to this discussion). The abstract reveals three things needed to produce a reaction on the copper:

1. presence of acetone on the copper
2. presence of ambient light
3. presence of water vapor (humidity)

The resulting reaction is the slow formation of acetic acid. This is also present in vinegar. I'll let you springboard your thoughts from there (especially if you've ever experimented with copper and vinegar before).

Now, we know that:

1. humidity and light both help to accelerate oxidation
2. acetic acid is an oxidizing agent
3. copper reacts through oxidation to create copper oxide
4. copper oxide is evidenced on copper through a change in the surface color

When using acetone, it has been said, sometimes there is no adverse effect on the copper coin, but sometimes there is questionable color.

We are able to deduce from what we know that this "sometimes" occurrence most likely happens because the acetone had not been properly rinsed from the coin and the coin had been subsequently left in a well-lit, humid environment which facilitates the rapid conversion of the acetone to acetic acids, thus facilitating the oxidation of the copper to copper oxide resulting in the questionable coloring of some copper coins treated with acetone.

If one wants to prove such a thesis, then one is more than welcome to experiment at one's own leisure.


edit: changed "amino" to "acetic" (in red), sorry for the confusion

 

Love abstracts.......used them in college.....and life. Resulted to.......split decision.

You guys can pull up the Stevey Winwood thingy.........

 

I think you're off-base (sorry) here.

1 is questionable -- humidity catalyzes some oxidation reactions, notably "rusting", and light can drive some oxidations, but often just by raising the temperature.

2 is flat-out wrong. Acetic acid is not an oxidizing agent, not any more than water is. (Sure, a strong enough reducing agent will take oxygen from acetic acid, but the same is true of acetone, or water.) Mostly, it's just an acid, and not a very strong one. (Oh, and "amino acids" is a red herring. They have nothing to do with this chemical system.)

If acetone really is being converted to acetic acid, it's because the acetone is being oxidized by air in the presence of copper, light, and humidity. It's a very harsh oxidation, if it's enough to tear off one carbon from the molecule's backbone. I don't know what level of illumination they used in the cited study, but I'll bet it was a lot stronger than direct outdoor sunlight, which in turn is a lot stronger (because it includes UV) than direct sunlight coming in through a window, which in turn is literally ten to a hundred times more intense than normal indoor lighting.

Even if you do get acetic acid, that by itself isn't going to attack copper. It needs an actual oxidizing agent. Copper is lower on the activity diagram than hydrogen, so it isn't attacked by a simple acid. Nitric acid does attack it, because that is an oxidizer as well as an acid.

What even dilute acetic acid will do, slowly, is dissolve copper oxide, that brown layer that makes the copper look "normal". It's not reducing it (removing oxygen from it), it's turning it into a soluble compound, copper acetate, and washing it away. That will leave the copper "looking funny".

But I suspect what really happened with those copper coins Doug and others have seen is that the acetone, pure and uncontaminated, removed a layer of foreign material that looked like oxidized copper (producing an immediate color change), or removed a layer that was protecting a completely unoxidized copper surface, which quickly turned once it was exposed to air (and humidity and whatever else that air carried). But, of course, I wasn't there with a fully-equipped lab, so my opinion is only that.

 

From my experience, acetone is safe on copper, but I've seen it do weird things to aluminum. Anything is possible due to the variety of surface conditions you might find out there. I use xylene instead on aluminum coins.

Why is this such a point of contention? It's easy enough to just use xylene on copper as well. While I haven't had issues with copper and acetone personally, I find Doug's assertions plausible enough to make the switch to xylene and be done with it.

 

NPCoin, posted: "1. humidity and light both help to accelerate oxidation."


jeffB, posted: 1. is questionable -- humidity catalyzes some oxidation reactions, notably "rusting", and light can drive some oxidations, but often just by raising the temperature."

So, by your own statement above, #1. is true. Humidity and light (increase in temperature) aid the chemical reaction.

jeffB, posted: "But I suspect what really happened with those copper coins Doug and others have seen is that the acetone, pure and uncontaminated, removed a layer of foreign material that looked like oxidized copper (producing an immediate color change), or removed a layer that was protecting a completely unoxidized copper surface, which quickly turned once it was exposed to air (and humidity and whatever else that air carried). But, of course, I wasn't there with a fully-equipped lab, so my opinion is only that."

I don't think that is the case as coins with the exact same surface may or may not change. Want proof? Clean the surface of a copper coin and as soon as one turns blue, you can change it back to brown. Now, apply the acetone again and it turns back to blue. IMO, that removes the case of unoxidized copper and invisible foreign material.

 

@Jaelus,

I've put more assorted things on copper than I care to list. Most improve the eye appeal. The acidic chemicals seem to be the only ones that may cause problems that are difficult to correct.

Anyone interested can assemble a bunch cull Lincolns and start playing around with anything in the house or supermarket as a start.

 

Don't get me wrong. I don't believe that acetone will harm copper. I'm saying it doesn't matter as nobody is disputing that xylene is safe to use.

 

That seems testable enough, but I'm unclear on exactly what to do.

1) How should I clean the coin's surface? Shall I sand it? I'm assuming I just want to ensure that it's freshly-exposed copper.

2) Don't I have to do something odd to make it turn blue? I expected that I'd get brown, and might have to wait a while for that.

3) When it turns blue, how should I "change it back to brown"?

I want to try this, but I think maybe I'm misunderstanding you...?

 

Search the internet forums. Some of what you have asked is proprietary info.

Link what you find for all of us to discuss. I think one discussion was titled "The sun and the blue rooster." Perhaps, blue toned proof Indian cents will work too.

 

I think when someone finally reads the complete study besides me,( a long time ago), they will likely agree the ambient light level was not what you would have in your home and the humidity was also much! higher than most homes . There also seemed to be inconsistency in their 'scientific methodology' in my opinion, in that the process seemed somewhat stacked to produce such an effect.
Yes, the company sponsoring it was one that made a product they wanted to be safer and less lasting effects, for cleaning copper than cheap acetone. Sorry if I am skeptical ,

 

Well, at least you've described what to look for now. That's a start.

That really isn't true at all. When you say correct information, backed up and verifiable, I agree with you. When its a matter of opinion, we sometimes disagree.

I disagree with a lot of people. The fact is, you just happen to post a lot more than most, and are perceived as more authoritative than most. This makes it more likely that you'll post something that I feel requires a response.

You are also highly opinionated, and state your thoughts as facts. I know, I often do the same (although I try to differentiate my facts from my opinions). However, when you state "facts" with no evidence, I challenge you. If you can back it up with evidence, then I am convinced.

The discussion from knowledgeable chemists in this thread has gone a long way to at least explaining what could possibly be happening. Thank you all for that. I have contacted the authors of that paper, and hopefully they will send me a copy.

 

This is the blue rooster thread. It's long but has much to think about.
https://forums.collectors.com/discussion/977997/the-sun-and-the-blue-toned-rooster

July 29th, Rick Slow posted some nice images.

 

Love all your comments, very interesting and informative, thank you

 

GDJMSP , posted: "It only matters that it happens sometimes!"

 

Hurricanes only happen 'sometimes'.........

 

Let me try to answer the original question.

"Is [dipping a coin in] pure acetone considered "cleaning?""

Not really. It is considered conserving the coin, as it does not actually "improperly clean" a coin - rather, it removes surface contaminants. However, I would not use it on RD copper coins, as I have heard of adverse effects.

Which brings me to what we are currently discussing - will dipping RD copper coins in 100% acetone affect them for the worse? I have heard of this many times but haven't tried it myself. In fact, I have never dipped a RD copper coin in acetone!

But I will try and see the results.