Red Copper

[Merc]

Here is a question I have not seen before. How can old copper still be red? Copper will quickly oxidize and turn brown (and later green) after exposure to air and moisture. How can Indian head cents and even some large cents still be full red after so many years? These coins were not stored in plastic air tight containers like today's coins.

 

In Scott Travers Coin Manual 4th ed, he interviewed a dealer who said much of the red copper has been reprocessed to appear red again. Is this the case? Is there very little true red copper coins out there?

[nwcs]

Some coins are red because they were coated in various oils/lacquer that preserved the coin's surface. Some coins survive in red because of environmental factors favorable to the coin. Not all copper coins are just exposed to the open air. There are many red copper coins out there. But there are many fixed red coppers out there as well and it isn't easy to tell if you don't look at zillions of them.

[Merc]

I have seen older Lincoln cent rolls where the center coins protected each other and just the rims toned from the paper. The coins on the ends also toned. Were indian head cents placed in rolls by the mint?

[nwcs]

The mint didn't roll them but some banks did. And since copper can stay red for a long while on its own in favorable conditions some may have been rolled later. Still your basic premise is right: full red should be a bit rarer than we see for older copper. And detecting original red from fixed red isn't easy if you don't work at it. I'm no good so I rely on the services. You can sometimes tell a fixed red if it turns in the holder over a short time.

[Merc]

I am amazed that large cents can still be red. An early collector could have laquered them to keep them red but this would be unusual.

 

Here is a large cent I have that still has a good amount of red. NGC gave it a 65RB.

 

[Merc]

The reverse is nicer. I had to place it in a second post. I don't know how to make get this site to take 2 attachments in 1 post.

 

Overall the coin is about half red on the obverse and about 75% on the reverse. The strong light makes it look lighter and more red.

 

[Hoot]

Nice cent.

 

I don't think that laquering a cent would preserve its red color for long. laquer is an organic coating with lots of volatile and semivolatile compounds in it. These tend to evaporate over time and the laquer then draws in moisture. I believe that a coin that was not regularly attended to in such condition would turn brown and black fairly readily. Much of what is in laquer would likely be directly reactive with metals of various sorts.

 

I think that old copper with some red left on it is uncommon, but is the result of having been left untouched on the faces and in a relatively static environment over the course of time. Moisture is the great enemy of copper and so are corrosive gasses. As long as the place and medium of storage minimized a coin's contact with these nasties, then I believe there's a chance it would maintain a fair bit of red coloration. It's all a matter of rate-dependence, as eventually all copper will turn unless somehow sealed with no contaminants on the surface in a place where they will not gather any either.

 

One thing that may have slowed many a red cent's change in color are the oils that they were often coated with during Mint operations. I don't know how intentional the addition of oils was to such coinage (as opposed to simple contact with oiled machinery), but it appears to have been common.

 

Hoot

[BankNote1]

I do like that Large cent!!!

[4ucoin-migration]

Great coin. For one, I actually like the Red/Brown coppers better the Red. Seems they have more character.