Green film over coin

Gabe · Senior Member

Last month I cherrypicked a 1909 VDB 1DO-002, but the coin has what apears to be a film of green rust (or something like that) on both sides. I already tried using acetone, and allowed the coin to soak in vegestable oil for a month, but the crud does not what to come off. It is a shame, since the coin has EF details. Anyone have any idea what I can do to remove whatever is on the coin?

coop · Expert Member

At first I was thinking it was PVC damage. But it may have spent a long while out doors. If it is the dark green patenia look, it will not come off unless you want to ruin the coin. And ruin it will look like. Yjr top layer of coin will flake off totally looking pink it you try to remove it with an acid cleaner. Best to keep it that way. I don't think there is a solution for this coin. I've ruined one or two with that result. I would leave it as it is for now.

JRocco · Veteran Member

Hey Gabe,
It sure does sound like a corroded piece that might be too far gone already.
But I have soaked coins in mineral oil for over a year only to discover that some crud/verdigris and apparent corrosion does loosen up sometimes and leaves a respectable result.
No guarantees on anything, but I would throw it back in some mineral oil and look it up next holiday season Smile

Robert · Senior Member

Gabe,

Verdigris is a tightly adhering, natural corrosion product of copper. http://en.wikipedia.org/wiki/Verdigris
This is, in my experience, hard to remove.

For example, the skin of the Statue of Liberty http://en.wikipedia.org/wiki/Statue_of_liberty is made of copper. Over the years, the copper has naturally weathered/oxidized into "verdigris", giving her that familiar green look. When she was built in 1886, she was copper colored.

Damage from "PVC" or polyvinylchloride http://en.wikipedia.org/wiki/Pvc coin holders is also greenish in color but adheres less firmly to a coin than verdigris. (Technically, I think it's the plasticizers in the PVC that does the damage, not the PVC itself. If a coin holder is very soft and flexible, it may contain plasticizers and therefore may cause "PVC" damage. If the coin holder is stiff and somewhat brittle, it likely doesn't contain the plasticizers and may not cause "PVC" damage.)

These soft and flexible "PVC" coin holders, over time, tend to leave a hazy, slimy coating on the coin. The coating has a distinct "sickly sweet" smell. Some people have had some success removing this coating using a variety of methods. I'm not an expert on that so I leave it to others to say more on the topic.

So I guess my point is that there are different types of green crud that could be on copper coins. These are different substances due to different causes.

Hope this helps explain the possibilities.

coppercoins · Site Admin

Unfortunately it's probably there for good.

Gabe · Senior Member

It sure looks like verdigris. Too bad, since it would be a nice coin to have if it wasnt for the damage. From looking at it, I'm also starting to think that the coin has probably burried for some time, since it has the familiar look copper coins have when dug from the ground.

Rhubarb · Senior Member

Gabe,

I metal detect and have dug up coin's. If the coin is pitted all over similar to the one pictured then it's probably dug.

David

JRocco · Veteran Member

Hey Gabe.
Here is a real life example of what I have done with mineral oil. I picked up this really neat 1844 One Penny Model that was in really tough shape. I did nothing but put this in mineral oil for 1 full year. At the end of the year I removed the piece and gently used a softened toothpick to prod around it a bit and brought a little life back into this once dead piece. It is back in the oil for about 3 months this time and I will leave it there for a few more before looking at it again.
Yes the color did change from a green color back to a nice copper color.
And take a look at that nice crack too.
Before and after.

Robert · Senior Member

I have some of those "model" coins. Were you aware of all the varieties of those that exist?

This website http://wbcc-online.com/grtbrt/grtbrt4.html has quite a few interesting coins on it. I like the brass wedges on page 1.

JRocco · Veteran Member

Hi Robert,
I found that site back when I was researching these pieces.
I have the copper and silver versions, but still have my eye out for the Model Penny with copper ring and centre.
Thanks for the link.

JRocco · Veteran Member

I finally found one Smile

And she has a nice grease filled die also