Unusual toning on 2015D, looks silver

[mustbebob]

It seems logical that the conical face of the die striking a flat planchet can produce varying temperatures on the face of tAn example of pressure differences when a cone shaped object meets a flat surface, think of your head hitting the pillow after a long night of searching. Your rounded head (biological "conical die") produces a bowl shaped impression in the pillow.

There is an error in your theory. Firstly, the dies are conical when they are being hubbed. They are flat and the perfect negative of the coin when they are striking coins. There would be no temperature differential when a coin is struck from one side of the coin to the other. In addition, the striking is so fast that things like temperature variations are not a factor.

My theory on the color difference of Vivs coin(s) would be environmental or chemical. If a coin roll is left in strong light, the center of the end coins discolor. I think the silver color is a little more unique that the blues and purples we normally see on toned coins, but no matter what, toning is the result of a reaction whether environmental or chemical.

[VAB2013]

Thank you so much Bob for the explanation about hubbing and striking of coins, and how the toning works! I've never seen a toner with silver color, and the silver is really strong looking on this coin.

[jfines69]

I can not find what I was thinking of... I believe it was info from Mike Diamond and to do with some stuff on the die??? It may very well be something like chemical that Bob is talking about... Since it is on both sides of the coin I wouldn't think it was from being on the end of a roll??? I will keep looking for that ref!!!

[mustbebob]

Since it is on both sides of the coin I wouldn't think it was from being on the end of a roll

You are correct Jim. I wasn't saying that these coins were from the end of a roll but merely pointing out that toning can come about from that condition. Sometimes, the storage methods contribute to the toning. Older paper and some coin envelopes were problems years ago. The color on Viv's coin is definitely something you don't see too often but I would still consider it artificial toning.

[VAB2013]

Thank you Bob and Jim for further explanation! When I was looking online at some other toned Lincolns... I did not see any with a silver color, but I did see what was called violet which was really pretty so maybe that's what the silver is trying to be. Right now, it's not all that pretty with the odd circle of copper color on the obverse, but maybe it will keep changing. The reverse is actually very nice! Saw some beautifully toned wheats!!!

[enamel7]

Hey enamel, you are an expert! It's the LED lights making that silver look purple though. In hand you can really tell it's silver looking, that's why I put a dime next to it to try to show how silver it looks. It's just weird. Weight 2.6 grams, correct size for cent.

I appreciate that Viv but I still get a lot wrong, like this one for instance. Good thing we have people like Bob around!

[jfines69]

You are correct Jim. I wasn't saying that these coins were from the end of a roll but merely pointing out that toning can come about from that condition. Sometimes, the storage methods contribute to the toning. Older paper and some coin envelopes were problems years ago. The color on Viv's coin is definitely something you don't see too often but I would still consider it artificial toning.

Thanks for the follow up and correction Bob... Apparently my eye/brain interconnect was not working... I reread your post and have no idea how I got it being end of roll!!!

[jfines69]

Thank you Bob and Jim for further explanation! When I was looking online at some other toned Lincolns... I did not see any with a silver color, but I did see what was called violet which was really pretty so maybe that's what the silver is trying to be. Right now, it's not all that pretty with the odd circle of copper color on the obverse, but maybe it will keep changing. The reverse is actually very nice! Saw some beautifully toned wheats!!!

I still can not find that info... If I can find it I will come back and place a link here... If memory serves me correctly it was a whitish color not silver??? I have seen coins with a sliver/gray substance on that that looks, to me anyway, like the special grease used on CPUs to help draw heat from the CPU to the heat sink on our computers!!!

[Petespockets55]

There is an error in your theory. Firstly, the dies are conical when they are being hubbed. They are flat and the perfect negative of the coin when they are striking coins. There would be no temperature differential when a coin is struck from one side of the coin to the other. In addition, the striking is so fast that things like temperature variations are not a factor.

My theory on the color difference of Vivs coin(s) would be environmental or chemical. If a coin roll is left in strong light, the center of the end coins discolor. I think the silver color is a little more unique that the blues and purples we normally see on toned coins, but no matter what, toning is the result of a reaction whether environmental or chemical.

Thanks again Bob. I've noticed the effects of light on the end coin of rolls also.
Your explanation has finally sunk into my head that the conical shape is during the hubbing process.

I guess heat, as Enamel pointed out in the case of a torch or stories I've heard about ovens used to create toning, would probably be considered environmental.

[jfines69]

I found what I think it is - Surface Film Transfer (SFT - that's for Jon ) Error ref just mentions it http://www.error-ref.com/wastebasket...te_catagories/ with a reference to a CW article 5/2/11... I wasn't able to find that article but did come up with an article by Mike Diamond on 8/10/13 and it mentions SFT https://www.coinworld.com/news/us-co...eate-nove.html the images do not come up tho???