How to Tone Coins

Well, for my part I could have worded that better. I gotta learn to be more careful around here.

 

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No Mea Culpa from me...

I dropped "authentic" out of my answer because it did not mean Good or Bad in the context of the post. IMO it was used above as an UNNECESSARY adjective to the word "original." Therefore, there are STILL 2 different things referred to: apples & oranges.

 

Most happy that Mike checked back in..........

 

But what if you accidentally leave your coin in a sulfuric environment? The coin may look heavily AT though it's unintentionally toned.

 

I've always wondered what happened to the holdings of folks downwind from the recent Icelandic eruptions. Some of the (highly sulfuric) ash ended up over Britain and Europe.

 

I have been running a little experiment to induce verdigris on some American cents. I placed them in a small amount of Magnesium Sulfate (which I happened to have lying around) and have allowed the solution to evaporate in the sun, in the dark, and have added water to each dried sample just to re-dissolve it. There is no green color at all after 2 weeks.

 

Put them in a leather pouch in the sun and wait, and wait

Heat oven to 250 (?); turn off; insert pouch and wait, and wait... any pies you make may smell and taste funny afterwards.

 

What if you get your brand spanking new 2016 ASE coins in the mail, leave them on your table, cook a bunch of hard boiled eggs for a large batch of egg salad, and you also eat them right next to your coins (unintentionally and clumsily, of course). Your coins turn a dark, AT-looking color. It was unintentional yet it's consistent with an AT coin.

And, for those of you wondering, put a cull silver coin in a small container with a single crushed hard boiled egg in it. Wait 5-10 minutes and check out what happens. The example above wouldn't have as extreme of a sulfuric atmosphere as a container, but I'm mildly offsetting the open space with a larger quantity of eggs.

 

I don't think sulfate will do anything. It's not that strong an oxidizer or complexer, and magnesium sulfate isn't acidic. Salt (sodium chloride) plus air would be more likely to work.

 

This will not produce "verdigris" the point of the experiment.

 

I wonder if you need a copper oxide surface first? Green copper roofs proceed thru copper oxide first.

 

It doesn't seem to have done anything, but I have a couple in a NaCl solution and one is getting "a wonderful patina".

 

But it produces patina, at least on silver... I've experimented with it myself to test the scenario of AT/NT and intentional/unintentional. There's a dark goldish color that turns into a dark purple color the longer you wait. I've concluded that you'll need a high enough concentration of sulfur (e.g. crushed hard boiled egg in a small container). It won't look like most NT coins, but if someone were to accidentally leave it in a sulfuric environment without any intention of toning, one cannot rule out NT.

 

OK, let's change the subject from producing verdigris (green, blue patina) to toning silver. Try some of the off-the-shelf household products at the grocery store...

Now, I wish to thank members for educating me. I was taught that verdigris was the loose, green crud like that formed on/around the brass snap on a leather purse/pouch. While patina is the crust (green) that formed on metal - ancients, roofs, statues. I also understood that "patina" is often used to describe the "skin" on metal and can be any color.

BUT NOOoooooo. Seems that verdigris is another word used to describe the green patina on coins. Now, I am confused. Why would someone wish to take the verdigris/patina off a coin (very desirable on ancients)? Posters here often write about how to remove it. Are these posters confusing "good" patina/verdigris with "bad" patina/verdigris GREEN CORROSION?

Calling all chemists: Please further educate me. Thanks.

 

That's why I was trying to induce some verdigris on a cent. I was wondering if, carefully nurtured, it would grow up to be a patina.

 

Henley's book of trade secrets tells how to turn copper green.

Any help with my question above? Why does everyone want to remove verdigris with Verti-care if it is "patina" according to the dictionary.

 

As I understand it, the sense of "patina" is that it's a layer that adheres to the coin, while "verdigris" is a layer that forms on the coin but doesn't adhere well. They might have the same general chemical composition, but their structure is different.

An adhering layer can passivate the coin, protecting it from further damage. That's what happens with copper sculpture exposed to the elements (as long as those elements don't include too much acid from exhaust fumes or industrial sources).

The verdigris that we often see on coins doesn't always do that. It can form little puffy patches that don't stick very well, and don't protect the coin from further damage.

With silver, the patina doesn't provide complete protection from further damage, but it tends to form uniformly, with results that please collectors more.

 

EXACTLY as I learned in the 1970's. Photos coming! When did these definitions change and who changed them ... the Johnny come lately uninformed coin dealers that started PCGS? Here is one you young members did not know. Back in the 1970's "whizzing" was defined as chemical cleaning by an important numismatic organization...

 

Our definitions change as we learn more or accept more. @BadThad is welcome to help out here. Verdigris is a term we use for greenish deposits on a coin that can spread (Bronze Disease) if it is not tightly bound. If it is tightly bound, it could be a beautiful patina. That is my take on it, but I am more than willing to be educated by those who have dealt with it for awhile.

 

Image 0464 shows blobs of soft green crud (verdigris) on a half cent.

Image 0465 shows another part of the coin with a bigger blob of verdigris pushed up off the surface.

Image 0466 shows the verdigris removed from Image 0464 using a sharpened toothpick and proprietary chemicals hilarious: Only teasing, its MS-70).

Image 0468 shows what happens to the surface of a coin when the SOFT GREEN CRUD sits on it too long! The effect shown (corrosion) can be removed but not w/o striping the coin and its beautiful natural color and luster. Conservators would only work on that one area to lessen the effect while saving the eye appeal.

Anyone disagree? If not, I'll stick to MY long time definitions of corrosion, verdigris, and patina.