Update on PCV removal.....

KenzoT

To those of you who advised using ACETONE to remove PVC
residue from copper coins, ARE YOU NUTS?
Tried that with a 1948, heavy spotting with green slime, within 30 seconds the coin was almost purple and ALL the PCV was still there, after 1 minute, all was PURPLE and SPOTS were still there!
It may work on silver coins but to anyone with PCV hindered copper coins, I strongly advise against ACETONE.
MS-70 removes the green crud!
You may have to soak it for awhile and it may change color, but thats what Deller's Darkener is all about, isn't it?
Those of you who advised using ACETONE on PCV coated copper coins ARE WRONG!

crito

first, are you sure you used pure acetone? nail polish remover contains other chemicals. secondly, are you sure it was PVC residue? copper corrosion can have a similar color. lastly, I've soaked copper many times in pure acetone with no change what-so-ever to the coin. If the PVC has eaten into the metal, it will expose untoned copper when removed, which will be a different color, but never purple. Good luck.

Conder101

I've used acetone on copper for years and I have never had one turn purple.

The only times I have ever had acetone change the color of a copper coin was when the coin had been artificially toned in the first place.

Cam40

Those that say acetone will tone or ortherwise alter the surface of the piece may be useing a plastic bowl to hold the acetone?

LanLord

I too have seen acetone turn copper purple. Not every time, but it can happen. I wish I knew more about the reaction and why it happens sometimes and not others, I just haven't sat down and done any controlled experiments.

dorkkarl

like someone said, don't use nail polish, go to the drugstore, get pure acetone. sounds like you didn't have pvc, sounds more like a varnish-type residue, which would mix w/ the acetone to produce horrible results. got any digipics?

K S

KenzoT

I used acetone straight from Home Depot, not nail polish remover.
These coins have been stored for 25 years in Harco albums, the green slime is heavy in areas and acetone had no effect on it unless one is hoping to hide the green spots with purple color.
We are not talking about removing a little green, this stuff has had years to build up and it looks more like mold growing on the coins, not a slight greening. This stuff is hard to get rid of, but so far in my experiments the coins surface do not appear to have been eaten into by it.
As I said, MS70 removes the crud, but gives the coin a "dipped" look after some soaking.

MikeSettles

Acetone will not turn copper coins purple. The brown color on toned copper is copper sulphate. Copper sulphate is a translucent blue color. When this sulphate builds naturally over time, the crystals are randomly aligned and the translucent blue color mixes with the red color below to produce brown. If the sulphate process is accelerated, the crystals usually are aligned with each other and in the correct light, look purple. They can be made to look brown if something like oil or wax is applied to diffuse the light.

Odds are if acetone turns a copper coin purple, it has removed the oil or wax from an AT coin.

perfectstrike

Looks like the purple result means your residue had some organic (protein) and was not pure PVC. There is also a high probability of another contaminant (acidic) on the copper. I thought it would take some heat to do this, but a small amount of dilute citric acid is enough to cause the reaction.

I've got to thank everyone that posts about copper cleaning results. Maybe some day I'll have a free month or two to really dig into this.

perfectstrike

Cam40

I know what hes talking about on how thick and sticky the crud can get.It seems no matter how many `treatments`you can cook-up,it still wants to remain sticky and `dirty`....had to take a dremel tool to one once just to get it all off.Boy is the surface pitted.Looks like the moons surface.What can you do.The coin is doomed anyway.Whizz it......atleast the PVC wont continue to eat the coin away.

dorkkarl

try to use detergent 1st to reduce the accumulation of oil leached on the surface. "dawn", or some other grease fighting detergent should work. be very careful not to rub to hard, DON'T use a brush. in light doses, you can safely use such a detergent on both copper & silver if it is patinated already, unless there is something artificial on the surface. laundry detergent may work too, but is more harsh, & if powdered, must be carefullly mixed w/ hot water 1st.

if worst comes to worst, the coin may have to be acid dipped then recolored. this is a situation where the deller's darkener helps out. won't fool anyone w/ experience, but convincing enough.

keep us posted!

K S

edited to add: if detergent does not attack the oily stuff, it ain't pvc, it's something else.

crito

if the coin is pitted/porous after removal, it wasn't PVC. Here's a pic of copper corrosion, notice the different colors (and thanks to CoinDepot and UPS for leaving my bag of wheeties outside in the rain, grr.. now soaking in mineral oil):



here's a coin that was in a PVC holder for 30+ years, only took a few seconds in acetone to remove it. Most of the details came off with the residue, however. The spots that remain are corrosion.



and you can get green toning that looks a little like PVC. here's a pic from one of my early "liquid transfer" AT experiments; coin has no silver in it (copper/nickel composition), but plenty of green was produced:

BAJJERFAN

There are a number of known organic compounds which will produce a purple color when reacted with copper in its oxidized cuprous state. This can actually be used to quantitate the amount of copper in a given sample. The PVC "green" is consistent with the formation of cuprous chloride on copper coins and silver coins alloyed with a significant amount of copper such as the Morgan dollars.
Methinks that your acetone is contaminated.