Why is Preservation such a bad thing?

Yes, but acetone will not react with metal, whereas acetic acid ( including substances containing it, vinegar, ketchup ( catsup) taco sauce, etc. is an acid ( abeit a weak acid) and can cause bad reactions with metal, especially copper based coins. It is usually this problem that limits acetic acid use.

 

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Lemon juice diluted in water is sometimes used to clean ancient silver. It's particularly useful in removing spotty toning, applied topically with a toothpick. I've had good results with this technique. I would not use it on bronze for the reasons Jim stated.

 

Why is Preservation such a bad thing?

It's not. It's a good thing. Harsh, abrasive cleaning is a bad thing.

 

Harsh and/or abrasive cleaning is a bad thing.

 

Acetic acid has a ph of ~2.4. That's well above the threshold of doing anything to silver or any of it's naturally occurring oxides.

Got me a degree in geology too.

Silver has a very narrow range of acids that will affect it as opposed to whatever is on it.

Using it on pennies wouldn't make cents... it would make trash. Although it does do an excellent job removing organic residues from the semi modern coppers I've played with it shines them up too bright and then you have to artificially age them.

Yes that's possible and way easier than you'd suspect.

 

The real trick is in finding a way to micropolish coins evenly with something softer than silver and that they'd naturally encounter in their normal everyday use as circulated coins as opposed to using a whizzer of some sort.

That I'll let you all speculate on.

 

"finding a way to micropolish coins evenly with something softer than silver and that they'd naturally encounter in their normal everyday use"

You mean like, fingers?

 

no though you're both cheeky and clever

 

Hasn't come up as an issue actually so it must not be noticeable at either a glance or 5x. Polishing may not be the correct term for undoing or making less severe the damage already done to the coin...

 

Indeed. Any kind of polishing will destroy the flow lines- something readily apparent to knowledgeable collectors.

 

Acetone leaves a water repellent surface treatment? Please explain.

 

Acetic acetic and I'm assuming acetone (I don't use it since its vapor point is too high to apply heat to the coins and expand the metal) leaves a water repellent coating on the coins.

Kind of like WD-40 does with tools. It inhibits bacterial growth and water penetration when it dries because it is a non-polar solvent despite being water soluble. It leaves a non-polar residue which is repulsive to water because water is polar. Your coin will not become and algae farm like so many do/are.

As to who isn't seeing it; it's the professional collectors at crowds and numastists at grading companies.

It's 100% possible to polish the surface of a coin and improve the appearance of a coin while undoing some of the original damage done. You just literally have to not leave fingerprints.

The term I originally used was micro polish which implies (from Websters):

1. A scale of physical consideration or of bounds having a characteristic dimension typically ranging from 1 to 999 µm (under 1 mm)

No matter how hard you try you aren't going to see that at a glance. Cope.

Its dependent on how soft your polishing agent is, how random its movements is across the coin, how the pressure is applied, whether or not it is constantly applied and the amount of pressure you are applying.

I'm not sitting there with a tool of some sort polishing the coin. I'm highjacking a natural process and putting it to work. The coins I process that had flaws have them reduced slightly. Improper cleaning becomes just cleaning etc... The coins with clean fields maintain clean fields.

Not just possible but happening.

 

I am a coin snob, if cleaned and stated cleaned I do not collect. I have been told by much wiser and knowledgeable collectors that many coins have been cleaned properly and thus grade so.

 

That take too long I like to use my Phillips screwdriver and finish it off with a dremel tool and wire brush

 

This seems to reflect confusion about TPG terminology. "Improper cleaning" and "cleaning" are pretty much synonymous.

If a coin is only "properly cleaned", the TPG will just give it a numeric grade; they won't mark it as "details", "cleaned", or whatever.

If you crack out a coin that's marked "improperly cleaned", do something to it, resubmit it, and get it marked "cleaned", that doesn't mean that you've undone the previous damage. It just means that they've classified the coin's damage in a different way.

"Proper cleaning", from the numismatic perspective, is cleaning that does not affect the coin's metallic surface. But that surface is delicate. Even friction from a soft rag can damage it. Once that damage is done, it can't be undone.

You seem to dismiss the importance of scratches you can't see. If I wipe the field of a proof or uncirculated coin, I won't see scratches, but I'll see a distinct change in the way light reflects from the coin -- its luster. That change makes it easy to see that the coin has been improperly cleaned.

You have a different perspective on all this, coming from an archaeology background, and that different perspective is valuable; I'd like to learn more from you. But also keep in mind that the community here includes chemists and metallurgists, as well as numismatic experts. You can learn from them as well, if you're interested.

 

Proper cleaning from a numismatic perspective is undetectable. If you can detect it, it is "harsh cleaning".

 

I have no idea of what you are trying to say, but acetone has such a high vapor pressure that it is gone quickly and leaves behind NOTHING.