Does toning ever stop?
prenum
Posts: 254
I honestly don't know (all my chemistry was taught by a guy named Oswald). I have always been under the impression that eventually all silver coins, when exposed, turn black. I've never seen an ancient silver piece that was toned. I have seen some very early British coins that were beautifully toned. How could toning stop? Copper always seems to turn dark brown.
Someone, with creditentials, must know the answer to this.
Someone, with creditentials, must know the answer to this.
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<< <i>I honestly don't know (all my chemistry was taught by a guy named Oswald). I have always been under the impression that eventually all silver coins, when exposed, turn black. I've never seen an ancient silver piece that was toned. I have seen some very early British coins that were beautifully toned. How could toning stop? Copper always seems to turn dark brown.
Someone, with creditentials, must know the answer to this. >>
Ancient coins generally were dug from the ground and cleaned, not the type of environment that is at all conductive to producing beautiful toning. Also, the quality and purity of the metal was crude at best. Furthermore, there's not a huge moon-money market for beautifully toned ancients, so nobody is *trying* to produce them
on a coin that stabilizes the surface of the coin. Unless exposed to
high sulfur content, heat and humidity, the coin should remain stable,
at least for a human lifetime.
Camelot
<< <i>Do threads about toning ever stop?
-Amanda
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<< <i>Do threads about toning ever stop?
No, but eventually they turn black.
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edited to add that this post and most of my toning science posts apply to silver coins only. I haven't looked at the science behind other toned coins much.
<< <i>As an aside, I periodically check some of my morgans that I have in my safe deposit box here in Portland, Oregon. I swear that the colors on many of them are getting slowly more intense each time I check on them. I have some moisture absorbtion materials in the box too, but I wonder if the dampness of the room is promoting more color.... >>
I'm not sure how dampness affects toning but generally water is more likely to increase the rate of a chemical reaction rather than decrease it. Water is generally undesirable in coin storage. I'm told that the fancy banks humidify the vaults to protect papers from drying out. You might shop for a bank in a lower rent part of town w/o a humidifier. That is, unless you live in a humid part of the country. If you choose to rely on the water absorbing material make sure you get some that changes color when it becomes saturated and change it frequently.
I'm not suprised you see changes. Jerry
--
<< <i>Entropy happens... >>
I started to say smoething about entropy in my first post, but I just didn't care enough to.
Oh, sorry - that's apathy. Never mind.
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After all the Coins in the market are toned will they still be selling a.t. a premium?
<< <i>To answer your question as simply as possible, NO. I read in some Numismatic Editorial that toning is to coins as rust is to iron.
THat is correct. Sometimes rust is attractive on iron and sometimes it forms a passivation layer and stopps rusting. Silver sulfide will never become as deep and invasive as iron oxide will. Perhaps patina on copper would be a better analogy. Notice that modern artists can put patina on copper that expertly imitates the thousand year old patina on a european copper roof.
Recognizing that toning is actually a surface defect is probably one reason I'm not attracted to toned coins..call me a geek...
--Jerry
<< <i>Does rust sleep? >>
Rust never sleeps.
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<< <i>I'm not sure how dampness affects toning but generally water is more likely to increase the rate of a chemical reaction rather than decrease it. >>
The redox reaction that results in the silver sulfide layer and the toning REQUIRES water to proceed. It doesn't have to be liquid water, water vapor in the air will work. So the lower the humidity levels the slower the toning process is.
<< <i>Does rust sleep? >>
Does....RUSS.... sleep?
<< <i>
<< <i>Does rust sleep? >>
Does....RUSS.... sleep?
Na...He just keeps moonin.. MBT.........
..............................
Proud recipient of two "You Suck" awards
<< <i>
<< <i>I'm not sure how dampness affects toning but generally water is more likely to increase the rate of a chemical reaction rather than decrease it. >>
The redox reaction that results in the silver sulfide layer and the toning REQUIRES water to proceed. It doesn't have to be liquid water, water vapor in the air will work. So the lower the humidity levels the slower the toning process is. >>
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Absolutely correct. Water (gaseous), temperature variations favorable to chemical reactions, and H2S (gaseous)--are
the three big variables.
--The key point is you need sulfur (H2S, etc) for silver toning. Stop the sulfur, stop the toning. Sulfur comes from
coal burning electric plants, cars, and volcanoes---2 of which are recent phenomenia of city life. Continued exposure
to water results in something different :copper oxidation--but who keeps coins underwater? The pits you see in
many old dug-up coins, and improperly stored coins from Florida, Hawaii, etc. isn't toning. It's enviromental damage.
no.
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