How do you dry a coin you have dipped?

I read your "trade secret" statement in passing through this thread initially, and thought you really don't want to know the ramifications of improper preparation steps, but let it pass without comment until I made the most expensive cleaning mistake of my long "conservation" education process.

Over the years, as a scientist, I've developed proprietary processes which are harmless to a coin, but will reverse environmental deterioration conditions without hairlines, etc..

I'd never tried a cleaner as Acetone which had been stated innocuous in many threads, which I was familiar as a volatile solution. I'd although in the distant past seen the damage caused by various stated "safe" commercial cleaners.

I was taking several valuable scarce date/condition Gold coins to a distant show for submission through a large volume dealer belonging to a same group as a dealer associate of mine.

One of the coins was a MS64 1909 Double Eagle which I'd previously removed from one of the top two premier TPG, for submission to the other for grading comparison. I've attached a rough image of the coin in its "Air-Tite" temporary holder, before making my expensive mistake. The coin had been in a slab for ~20 years, and had a surface "toning" which I've seen on many of my slabbed coins.

I thought I'd see if Acetone which I'd purchased in the past, still in a sealed container, would have any affect on the toning if I added some solution into the holder, and just "sloshed" around for a short interval after lifting an edge and basting beneath. After closing the holder, and rotating for ~1 minute, the coin was welded to the holder, ruining a ~$6500 coin.

When the coin was eventually extracted, it had plastic residue on the bottom face, a film on the top face, and plastic on my fingers, with epidermis damage.

I've now another "opportunity" to try reversing damage which would have been prevented if I'd used normal precautionary measures than accepting stated experience of others. It's believed I'll eventually have an "authentic" coin with an ~75% reduction in value.

JMHO

 

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So you added the acetone into a plastic holder with the coin still there? Further treatment would have most likely dissolved the rest of the plastic without harming the coin, as the plastic seemed soluble in acetone as most plastics, including air-tite and every TPG slabs I know. Acetone does remove lipids from the skin which produces the dry whitish appearance, but they will return after a short while.

 

@imrich posted: "Over the years, as a scientist, I've developed proprietary processes which are harmless to a coin, but will reverse environmental deterioration conditions." I'll tell you some if you tell me some.

"I'd never tried a cleaner as Acetone which had been stated innocuous in many threads." While acetone is one of the dip preps, I always thought everyone knew acetone melts plastic! "The coin had been in a slab for ~20 years, and had a surface "toning" which I've seen on many of my slabbed coins." That is the "good" haze the TPGS's like. It is called "skin." It is best to leave it on a coin.

"I thought I'd see if Acetone which I'd purchased in the past, still in a sealed container, would have any affect on the toning if I added some solution into the holder, and just "sloshed" around for a short interval after lifting an edge and basting beneath. After closing the holder, and rotating for ~1 minute, the coin was welded to the holder, ruining a ~$6500 coin." Acetone melts plastic.
"When the coin was eventually extracted, it had plastic residue on the bottom face, a film on the top face, and plastic on my fingers, with epidermis damage." Many coins like this are sent in for conservation. The "fix" is very simple yet time consuming. The coin and the plastic are put into a covered dish of fresh acetone. Several steps later using more fresh acetone, the coin is restored to normal with no loss of value..

 

Yes, Acetone will melt some plastics at a certain rate, which one wouldn't expect to a gel state in ~1 minute. How long do you think for TFE or FEP? I believe numerous plastics could be listed which wouldn't be affected.

I'd explain why your conservation statement wont work, but realize you probably don't understand, or you wouldn't have made the statement. I'll just suggest that you create the condition I've described, and then reverse same by your solution described, and then you MAY understand the dilution/miscibility/evaporation process.

I have a lengthy attentive process that will return the surfaces to the original golden color without affecting luster, but would constitute a "genuine" rating by one of the premier TPG."

I can show you some severely hideous examples of your "skin" which received a MS65 rating for a coin with significant offensive bag marks and rub on the devices, by the same TPG who apparently approves of environmental damage.

JMHO

 

I don't know of any type of coin holder that's safe with acetone. They melt. There are some plastics that you can even store acetone in but I don't think any of them are used to make coin holders. There are squirt bottles that are safe and handy to flow acetone over the coin.
There is no reason the coin could not have been saved without any damage.

 

You are correct, that some solvent dispensing plastic bottles may be capable of storing and dispersing Acetone, but generally I believe that this "cleaner" is considered to be quite dangerous:
https://www.msdsonline.com/blog/msds-chemical-management/2013/06/18/acetone-the-hidden-hazard

Do you know of a static process that will reverse the gravity extrusion by coin weight pressure of liquified plastic into the intricate crevices of a complex surface designed coin, with complete removal of residue? Vapor honing would probably generate as close to complete reversal possible, but generally wouldn't be applicable for a high vapor pressure flammable solvent.

You may be correct, about a known complete reversal commonly utilized process, I'm just not familiar with same. I initially tried the process suggested, with others, for a day before posting in the thread. I'd be amenable to your proven/documented recommendations.

The process I applied in testing the "cleaner/diluent" was of poor judgement when not knowing the construction material of the coin holder. I normally would use a ceramic/glass holder, which was unavailable at the time.

JMHO

 

It would take me a while to understand what you just posted but I'm not going to do that. I understand when and how to use acetone and that's all I need to never have a problem with it.

 

Thanks Doug, I already had that when I responded to the comment about the melting of plastics, and asked about the Fluoroelastomeric "plastics" such as in the far right column of the chart (i.e. Polytetrafluoroethylene).

Once the plastic was extruded into the coin crevices, and welded in place, surface processes, unless impinged with appropriate solvents, are virtually useless.

I have a proprietary generally harmless (i.e. when patiently/attentively applied) process developed for generally cleaning coin crevices and surfaces without altering luster. The process works best with non-oxidizing "noble metals" as Gold.

Your input, as always with useful information, is appreciated.

Respectfully, Rich

 

@ imrich posted: "You are correct, that some solvent dispensing plastic bottles may be capable of storing and dispersing Acetone."

I agree but I use glass.

This paragraph is WWAaaaaaaaaaay over my head. "Do you know of a static process that will reverse the gravity extrusion by coin weight pressure of liquified plastic into the intricate crevices of a complex surface designed coin, with complete removal of residue? Vapor honing would probably generate as close to complete reversal possible, but generally wouldn't be applicable for a high vapor pressure flammable solvent."

"You may be correct, about a known complete reversal commonly utilized process, I'm just not familiar with same." I am correct and I posted the method. I've conserved almost twenty coins covered in some form of plastic, and posted the method in a post above. I initially tried the process suggested, with others, for a day before posting in the thread. ...and what happened?

 

The kind of acid in commercial coin dips like Jewel Luster. I believe there are many threads on coin talk about the ingredients in "dips."

 

While doing postgraduate work at Clemson University, my labmate came in carrying his motorcycle helmet and said something about having a stain or dirt on it. I turned just in time to see him grab the acetone squirt bottle, but my scream came a second too late... luckily he was able to buff out the haze with toothpaste.

@imrich soaking a coin in acetone will eventually reach all the creases and crannies of the coin. Ultrasonic might help as would using a stream of the solvent, however prolonged soaking should do the job.

 

It is quite reasonable to believe that all the professional conservation services in the world use these machines for something - no?

 

The problem is not broken-down polymer removal, the right organic solvent(s) will dissolve it (THF comes to mind). The issue is that acetone broke the polymer producing shorter-chain materials which likely have the solvating power to strip the surface.

 

Solvating power, on it's own, shouldn't strip any toning though...should it? PS, I love THF

 

Probably not the toning, I was referring more to the natural, organic-type surface layer, some call it a "skin". The slow adsorption of elements, compounds and the oily, lipophilic materials from humans....it's interesting science IMO. I've theorized the the process many times in my mind. It takes decades for coins to develop a "special" patina (especially gold), one that is barely noticeable and not at all distracting but the trained eye can spot it. I call it a Haze Layer. It's the composition and thickness of that layer that creates the patina.

I know all the experienced guys know what I'm talking about.

THF - Me too! But I avoid using it, been over 15 years since I needed it.

 

And another thought - I'm no polymer chemist, organic is your world but... can't a chain break at the ether linkage with a little hydroxide catalyst to create a carboxylic acid (hydrolysis)?

 

Chemicals can do wondrous things I tell you...wondrous!

 

Would you guys talk in English?