For the sake of Science, I decided to sacrifice a few cleaned silver coins. They were all purchased below spot and as such I do not feel any regret for irrevocably destroying their numismatic value (except for one AF-3 which I got ripped off on, in which case I was aiming for revenge). The results: worrying. In about thirty seconds I was able to make a uniform, colourful tone using materials that everyone reading already owns.
You will need:
- A spoon
- A barbecue lighter
- A glass of water
The procedure:
1. Place the coin in the spoon.
2. Turn on your lighter and heat up the coin. Use proper torch etiquette and make sure the tip of the orange triangle is just barely touching the surface of the coin.
3. After about 20 seconds of this, the coin will begin to turn slightly yellow. When this begins, turn off the lighter and watch it tone before your eyes. If it doesn't tone, add a bit more heat and repeat. If you leave the lighter focused on one point, the butane will exclude sulphur-containing air from that point and it will stay untoned.
4. Be safe and lower the coin and spoon into the water. Wait until it stops hissing and sizzling.
This works because there are multiple ways to speed up a chemical reaction (silver and sulphur in the air combining, in this case). You can increase the concentration of one ingredient, as seen in the hard-boiled egg method, or you can lower the activation energy by heating things up. Hot molecules are more likely to stick to other molecules, so with a bit of heat you can watch years of normal toning happen in just a few seconds.
Here are the four test subjects. There aren't any before pictures, but they all began the experiment as a blinding, cleaned white.
The 1-gulden was the first and worst, as the constant gas pressure in the center from the lighter blew away all the normal air for the duration of the experiment. As a result, the edges got blue and the middle hardly toned (it starts out yellow, then goes to blue, then black. getting a rainbow may be possible but would require finesse). Seriously, look at it, it's terrible:
The 2-reichsmark was a case where I was still a bit squeamish about messing with with a historical coin's tone, so I went lightly. It ended up looking better than it was when cleaned, though.
This was an absolute steal, but had a horrible, horrible, HORRIBLE cleaned luster that had no business being on such a worn coin. It's my favorite from this lot, getting a really nice golden colour - it probably won't fool anyone (not that I'd try, this was done for aesthetic reasons only) but I like it.
I don't think it would be possible with just the equipment I have to fake one of those beautiful Morgan rainbows we all love, which is good news. But if you have any horrible cleaned coins that you want to try and tone, this could work... if you're sure you won't miss anything you're working with. I was pretty happy to have discovered this on my own (even if other people have already done this, I don't know about them). Plus it's quick!
Posted 03/23/2013 8:34 pm
