To Dip, or not to Dip, that is the question.

To whom? For experienced collectors like yourself, there would be no real upside in dipping the coin since the luster already seems to be impaired. My point is that a lifeless white coin will probably be easier to sell than a lifeless, deeply toned, possibly artificially toned coin.

 

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Doug, would you consider the coin a problem coin as is?

 

CoinChemistry 2012 - Although its my own fault here ... every collector regardless of his numismatic level has his own self training, inhibitions and therefore opinions. True I never disected NGC or PCGS in terms of a stereo microscope ... it could be seconds ... and probably most often its eye-balling the coin. But viewing a coin under a SM will always tell you if the surface has been played with ... I was giving them the benefit of the doubt. Gurney and myself did discuss with a NGC supservisor some of the methods they use to grade coins at the recent Mexican Coin Conference is Scottsdale for counterfeit 8 Reales. Its a quick factory type operation - for sure. The cleaner I developed is strictly based on being safe on copper substrates. If you know who I am then this statement is obvious. I do not expect anyone to believe me ... the coin cleaning topic is IMPOSSIBLE in terms of teaching, changing peples minds, etc ... its always and always will be a merry-go-round of opinions. My formula is my own and its proprietary and I simply had the opportunity to create it. I do not blame you - for years even I believed there is no way to clean copper. Most experts go with xylol. Its good - but messy and takes time and the dirt in some ways just floats on the surface of the coin so you need to be MORE careful. Also CC2012 its a singular chemical, does not evaporate very well and has no built-in synthetic detergent system. Patina change does create a new look to the coin but as I said removing the green surficial verdigris - it's worth it - each coin is a case by case scenario - of course. I do use it on silver since it has no effect and it does well to remove the coloration of that 5% Cu on silver type alloys. <VVBG>.

John Lorenzo
Numismatist
United States

 

Well, quite a few of you echoed some of the same things I had been considering, mulling over for the last few days. I do have the plus side of having the coin in hand and I know that it is justifiably hard to gauge all the merits and defects of a coin from a photo. With all that in mind I do not think that I am going to dip it before I send it in, although I have dipped other coins prior to submitting them. Should it come back with a solid grade I shall be happy, if it comes back artificially toned I would be a little bit non-plussed but since I was fully aware of the possibility before I even purchased the coin and negotiated based on the worst possible scenario I don't think too much can go wrong. It'll probably go in the mail either late this week or early next week and I'll let you guys know what the ruling is when I get the results.

Thanks.

 

FYI - Kentucky has PhD in chemistry and I agree with him. Fluorine is one of the LEAST reactive elements on the periodic table!

Fluorine is the worst leaving group in organic chemistry, it's not going to dissociate from a C-F bond. The are only a few scenarios where F will leave, i.e. attached to a carbonyl carbon or an aromatic ring, even then it would only happen with a very specific pathway/reaction involving chemicals only a chemist would have at hand.

Halogen groups that are good leaving groups are iodine, bromine, & chlorine.....and fluorine behaves NOTHING like those.

 

Please explain how a non-ionic "fluorocarbon" can possibly dissolve an ionic salt like verdigris? I'm very interested in hearing the technical details because that defies everything I know about chemistry.

 

Apologies in advance:

You must dip it, dip it good...bum, bum---bum, bum, bum -- I say dip it!

 

Sorry, fluorocarbons are not very reactive at all (except perhaps in the upper atmosphere with ozone). I have taught introductory college organic chemistry. Perhaps you can give me a reference, I have lots of organic texts. BTW, except for hands-on experience (which I respect) do you have any chemistry background?

 

As the Caterpillar said to Alice, "Who are you?"

 

I have great respect for BadThad, and he knows more about surface chemistry of metals than I probably EVER will, but I think he meant to say that fluorine is one of the most reactive substances in the world, but once reacted, it tends to stay reacted, that is fluorine chemicals are quite unreactive.

 

Anyone ever consider the ultrasonic coin cleaners? How about the suggestion of boiling them? Seems neither method would leave surface marks?
I personally do not like toned coins, or black oxidated silver. I think a uniform silver color looks good in an album.
Copper is probably the hardest, because you risk changing a steel or chocolate patina to shiny copper. Any favored methods for copper coins?

 

I have concerns from AT to environmental damage, but as discussed in a recent thread, I am tough on coins with terminal state toning. Since, in my mind, it is already a problem coin, I see no real danger in dipping it.

 

Okay, call me crazy, but I like the coin. If I were in the market for that date and coin now, I would have bought it. I don't object to the toning, even though it is not the normal Barber type toning pattern.

 

@Kentucky and @BadThad

The post I responded to said that fluorocarbons are inert (i.e. completely chemically inactive). When I made those comments, I was referring to potential side reactions with the air and the immediate environment and not necessarily the coinage metals themselves. We were always taught that the halogens were excellent leaving groups and that alkyl halides were generally reactive in substitution and elimination reactions. Now I concede that fluorine is a much poorer leaving group than Cl, Br, or I, but it is my understanding that it can still undergo these reactions. There is a difference in saying that fluorocarbons are less likely to engage in these reactions than other alkyl halides than to suggest that it never happens at all. Here is an example from the Journal of Organic Chemistry demonstrating an intramolecular SN2 reaction with fluorine as a leaving group: http://pubs.acs.org/doi/abs/10.1021/jo802819p. Here is another: http://onlinelibrary.wiley.com/doi/...sCustomisedMessage=&userIsAuthenticated=false. (And I show these only to suggest that fluorine can serve as a leaving group as the other halogens, not to imply anything more). My point is and was that I wouldn’t rule out the possibility of a reaction and thus wouldn’t consider them inert.

And it is also my understanding (and I would love your opinions as it is something I have contemplated in other scenarios such as the use of canned air with alkyl halide propellants and any potential reaction should any propellant land on a coin’s surface), but fluorinated organic compounds make excellent electrophiles and thus are used in inorganic chemistry through oxidative-addition and elimination reactions. Now I understand that this often happens with coordination compounds, but nickel and fluoride compounds are exist. Isn’t it plausible that reactions with the surface of a coin containing nickel or platinum (for instance) could occur using similar chemistry to these reactions?:

http://pac.iupac.org/publications/pac/pdf/1972/pdf/3003x0551.pdf.

And I want to apologize to @Kentucky if my original post (in terms of tone) might have come off the wrong way. I truly hope this discussion can turn into something educational.

 

There was no disrespect meant to @Kentucky at all. And here is a reaction that illustrates fluorine acting as leaving group and dissociating from a C-F bond in the absence of an aromatic ring or carbonyl carbon:

http://pubs.acs.org/doi/abs/10.1021/jo802819p

 

No offence taken. Originally I was just wondering what ColonialJohn had come up with to clean copper that was related to fluorocarbon technology. Fluorine can be a leaving group, but in the examples you gave, the other reagent was an organo-lithium or sodium hydride, a couple of chemicals I would hesitate to mess with outside of a properly equipped chem lab. These dudes are pyroforic (catch fire spontaneously in air) and require an inert atmosphere.

Not to take up too much more space, but inert is in the eye of the beholder. We stopped calling the Inert Gases inert and now they are the Nobel Gases, however there have been few compounds made from them in over 50 years.

 

AMEN. Stay with xylol ... for your coppers.

LOL.

JPL