How to Tone Coins

How do you keep a Red Lincoln red when all it takes is oxygen to tone it?

 

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I think light, temperature, and humidity are all facters as well. Im just thinking about different pieces of copper water pipe i have seen in homes over the years. If i remember correctly, it seemed that the pipes that had hot water running through them stayed red longer than those with cold water. Thats just an observation from seeing copper piping in my parents basement.

Also i think the oils on skin will turn red copper to brown.

 

And time - lots of it under proper conditions.

 

I could see them hanging around for decades if packed tightly into a roll. Alone out in the air? Dunno - two years, maybe, if that? As Evan8 mentioned, how long does it take for copper pipe to darken? It should darken more quickly, not being alloy.

 

A trick question...right...keep it away from oxygen 1) seal that sucker up 2) put stuff around it that will react with oxygen.

 

An obtuse question. If they tone so easily, how do so many get into Red slabs?

 

And where the devil is Mike (@kaparthy)? He started this train wreck........

 

OK, I'll try again. The sealed slab will restrict the refreshing of any oxygen trapped before the slabbing and some of the oxygen might react with the slab material. Oxygen isn't THAT reactive, I breathe some every day.

 

No doubt; there's too much anecdotal evidence that slabs are sufficient protection (in most cases) to keep Reds from turning. My main concern is how they survived 70-80 years for some, staying Red the whole time, before reaching those slabs.

To be completely clear, I'm speaking in support of Doug's theory that turning Browns back into Reds is not only possible, but actively being done.

 

Accepted. Now, since circulated coins showing wear would be REALLY suspect if they showed up as red, what would be a good way to simply lighten coins that are too dark? Dellers will darken them., but where is the lightener?

 

You're the chemist. How do you reduce copper oxide?

 

In a damp/wet place with pure copper after being heated. Not a valid comparison.

BTW, at 2 years, every penny you find in circulation before 2014 should be brown. I am finding them from the 1980's still full red. A friend of mine has full rolls from the 1930's full red. And note I said under proper conditions. I guarantee circulated pennies have not had proper storage.

 

Post #164

 

Then why did you ask "where is the lightener?"

My head is spinning. First the VAM thread, now this. Think I'm done for the night.

 

That was from other work not coin related. Don't want to make them shiny bright, just lighten some of the really dark toned coppers I see that are lovely coins if they weren't so dark.

 

Here I disagree with both of you. I see NO DIFFERENCE WHATSOEVER in the toning rates of copper coins in or out of PCGS or NGC slabs, and old small ANACS slabs actually seem to accelerate toning of copper. I see zero toning protection in modern slabs.

 

So what do you think might work, Kurt?

 

Keep them tightly packed in full rolls and let the games begin. I strongly suspect dryness is key.

Oh, and I will experiment with the bell jar and hydrogen gas, but it will be a while.

 

Too bad the 1909 Lincoln cent is on the Opportunity Rover on Mars and not on a Jovian moon with a high hydrogen atmosphere. Probe to Io, anyone?

 

How to tone coins, Maine edition: Liberally wrap a coin in tinfoil (and I dont mean complain about it while you're doing it), then place the coin in the microwave. Set the timer for 6 minutes (no less) and press the start button. Presto! Beautifully toned coin