As a collector of coins I find myself often drawn not to the hard to get and rare coins, but to the ones that are unusually colored or marked by time in some way. I find myself after wondering why one coin might change color while another identical coin does not.
The following examples are from my Australian coin collection:
An uncirculated 1973 1 cent that is a deep blue in tone. I have the exact same coin also uncirculated from 1973 and it's fine and bright as the day it was minted.
An uncirculated 1966 2 cents that is actually a golden color but still with a full luster. And a 1972 uncirculated 2 cents that is a deep chocolate brown. I also have one that is a deep red color from 1968 (though this was given as being due to the Mint wrapping the coins in a high-acid paper for that year by mistake).
But the best by far is a 1985 10 cents coin, low mintage for that year, and a striking golden tone to it.
So what causes the toning? And why do some coins turn dark brown whilst other turn blue, or even a golden color? I'd love to know as I find them fascinating to look at.
Collector of Third Reich coins (1933 - 1946), and Australian coins.
Not swapping at this time.
Identical twins diverge in appearance with age, because they travel in diverging circles.
the main things that affect the surface of metals are chemicals, UV radiation, and heat, and combinations of all these factors.
atmospheric chemicals that are the most influential are hydrogen sulfide, and other sulfur compounds.
doubtless these chemicals can be found on the hands and in the pockets of all of us, in minute amounts. Then, it's a matter of time. It may be that some coins sit in a drawer for decades and steep, while others circulate daily and have the reactants brushed off them.
furthermore, the composition of the coins are not perfectly uniform in alloy or in mixture, the metalurgical arts being what they are, so small amounts of contaminants will be present in some blanks and not others. these minor elements in the alloy will also react with the environment in divergent ways, over time.
It is a wonderful topic and one of my favorite aspects of coins. i have some amazing iridescent rainbow bullseye toned french francs, (and others that are uniform slate grey). I just wish i could photograph the colored ones effectively. Some effects i think are optical illusions!
Jamais l'or n'a perdu la plus petite occasion de se montrer stupide. -Balzac
Hello
When I watch some coin dealers, and regularly sells coins with special toning, I think it chemically uses some substances to put on or let it steep the coin.
Yes, it is difficult to capture the uniqueness of colors and rainbows.
I like coins with a special color.
I am not experienced in it myself, but I was at a coin show recently. A vendor and a shopper were discussing toning. One of them suggested that you leave your copper coins in a box near your water heater to achieve a nice toning. He professed to have done this some level of success for a number of years.
It's reaction of the metal to different chemicals that causes the toning. I've seen that you can quickly tone up silver coins using mashed egg because the sulfur in the egg reacts with the silver
The old cardboard push-in albums used to tone up coins quite nicely, you'd get a ring of dark toning around the edge where it was touching the album and then lighter in the middle where it's away from the cardboard.
Quote: "Mr. Midnight"
It is a wonderful topic and one of my favorite aspects of coins. i have some amazing iridescent rainbow bullseye toned french francs, (and others that are uniform slate grey). I just wish i could photograph the colored ones effectively. Some effects i think are optical illusions!
I had some success with capturing my own, very nicely rainbow-toned 1 Franc Semeuse, which used to be my avatar (and probably will resume that role soon):
An extremely common type and date, but nonetheless an enduring motif and one that has been used on French coins since 1959.
Oh wow! I am so glad i began this thread now. I had no idea that artificial toning of coins was so prevalent. Made me take a second look at the ones I have as I'd like to think the toning was a product of natural aging. At least, that is why I bought them.
Collector of Third Reich coins (1933 - 1946), and Australian coins.
Not swapping at this time.
Quote: "Kipsley"Oh wow! I am so glad i began this thread now. I had no idea that artificial toning of coins was so prevalent. Made me take a second look at the ones I have as I'd like to think the toning was a product of natural aging. At least, that is why I bought them.
It usually is, but if a coin has been cleaned by dipping in acetone then all the lovely toning gets removed, I guess some people want to put it back on again, and some just want to make it look pretty so they can sell it for more. I don't use acetone on mine, I usually just give my coins a wipe with isopropyl alcohol when I put them into storage which removes any grease and grime from handling but leaves the toning intact.
Quote: "Kipsley"Oh wow! I am so glad i began this thread now. I had no idea that artificial toning of coins was so prevalent. Made me take a second look at the ones I have as I'd like to think the toning was a product of natural aging. At least, that is why I bought them.
It usually is, but if a coin has been cleaned by dipping in acetone then all the lovely toning gets removed, I guess some people want to put it back on again, and some just want to make it look pretty so they can sell it for more. I don't use acetone on mine, I usually just give my coins a wipe with isopropyl alcohol when I put them into storage which removes any grease and grime from handling but leaves the toning intact.
Acetone doesn't affect toning, I've soaked some major toned coins in acetone to remove minor surface issues. It's stronger dips that are made for the purpose of removing toning.
Quote: "Kipsley"Oh wow! I am so glad i began this thread now. I had no idea that artificial toning of coins was so prevalent. Made me take a second look at the ones I have as I'd like to think the toning was a product of natural aging. At least, that is why I bought them.
It usually is, but if a coin has been cleaned by dipping in acetone then all the lovely toning gets removed, I guess some people want to put it back on again, and some just want to make it look pretty so they can sell it for more. I don't use acetone on mine, I usually just give my coins a wipe with isopropyl alcohol when I put them into storage which removes any grease and grime from handling but leaves the toning intact.
Acetone doesn't affect toning, I've soaked some major toned coins in acetone to remove minor surface issues. It's stronger dips that are made for the purpose of removing toning.
Ah, ok, I've never used toning, but I'd heard that dipping takes the toning off. Whatever it is, it's those beautiful old but blasted white silver coins that are the prime target for artificial toning.
"Dipping" refers to holding the coin in a weak acid solution and is generally frowned on as it most certainly affects the coin's surface. Acetone is considered OK as it only affects such undesirable things as tape residue or glue.
I've never really investigated the possibilities of artificial toning, mostly because I live in a sub tropical climate where coins tone quickly and naturally. I have however been experimenting for some years with the creating of a perfect micro climate for coins which lack tone. After a lot of trial and error I've found the perfect method, which involves all the elements that cause a coin to tone. It only works on copper, bronze and silver - and silver is by far the quickest to react. I'd average it out at 2 months for silver, 4 months for bronze and copper can take up to a year. At the end of the process I have a perfect, naturally toned coin.
Of course if the coin is polished or abrasively cleaned then it's not going to be improved by a change of colour! The method I use will only work on coins which have been dipped or lightly cleaned. It's also dependent on high daytime temperatures, airborne contaminants, plenty of humidity and while I don't have the scientific savvy to prove it, I believe that the sea air rolling in with each high tide plays a huge role.
If you don't live in a semi tropical climate or you have a coin which is scratched and polished seemingly beyond repair you still have a good option. Touch Pieces! Every coin lover should have one! People across the world have carried "lucky" coins for centuries, it's quite possibly partly behind the earliest introduction of Maundy Money. I reckon we all have at least one of those magnificent coins which has been ruined by harsh cleaning or polished. Put it in your pocket with your car keys and loose change and let it "circulate". After a while, the abrasion against the other contents of your pocket and exposure to your dirty oily paws will change your ruined EF coin into a problem free VF one.
This has been discussed before and several Numista members have gotten into the most useful habit. Give it a try, what do you have to lose?
Non illegitimis carborundum est. Excellent advice for all coins.
Make Numismatics Great Again!
I really don't look for them but have some wood grains . And just found two Canadian 1973 1 cents with a very nice blue and purple.
Kipsley if you would like one I would be happy to send one to you. It hard to see in images.
