PVC on copper, what to do?

Pokermandude

Came across this key date Canadian cent in AU+ condition. Unfortunately it had been stored in a pvc holder for quite some time.

Is there anything I can do other than sending it off for professional help? I have used acetone with good results on silver coins, but I've had mixed results on copper. Sometimes it ends up discolouring the coin so badly that it actually makes it look even worse than with the PVC. The brown spot in the left obverse field may even be beyond-help corrosion.

Suggestions? The coin is valuable enough that I'd hate to make it worse.

AUandAG

Acetone is what it does need. Acetone does not discolor the copper. What you might have seen is the
fresh or damaged color underneath, once removed.
Not certain how happy you will be with the big spot. May be nasty underneath as well.

Pity it was not taken care of.

bob

brg5658

If you use acetone on it, and some of the "red/brown" areas become a dark red almost purple, then don't be surprised. Acetone is not "supposed" to do odd things to copper color-wise, but from many personal experiences, I can attest that it does. Acetone bathe at your own risk on red/brown or brown copper.

ricko

Acetone will remove the PVC.... but the damage will remain...Cheers RickO

Steve27

I've seen acetone affect the color on copper coins, but only if they had previously been cleaned.

lkeigwin

I did a few experiments with acetone and copper because I'd read and thought I experienced different things.

For a long time I'd heard "don't use it on red copper, it will make it sorta pink". And I seemed to remember this happening once long ago.

But another forum member said "Nonsense, acetone cannot harm metal. If you're seeing any change in color it is a reaction from whatever is on/into the surface of the coin. E.g., skin oil, airborne contaminants, etc."

Based on my experiments (several dozen coins, large cents to Lincolns, RD, RB, and BN), acetone is absolutely fine. 100%. Many early copper collectors use Xylene to treat old copper. It's another thinner/organic solvent harmless to copper...slightly oilier, so it doesn't result in that dried-out look.

As others have already said, acetone can't fix damage and can expose it.

brg5658 - I have witnessed red/purple/blue from MS70 on circulated copper, never from acetone.
Lance.

brg5658

<< <i>I did a few experiments with acetone and copper because I'd read and thought I experienced different things.

For a long time I'd heard "don't use it on red copper, it will make it sorta pink". And I seemed to remember this happening once long ago.

But another forum member said "Nonsense, acetone cannot harm metal. If you're seeing any change in color it is a reaction from whatever is on/into the surface of the coin. E.g., skin oil, airborne contaminants, etc."

Based on my experiments (several dozen coins, large cents to Lincolns, RD, RB, and BN), acetone is absolutely fine. 100%. Many early copper collectors use Xylene to treat old copper. It's another thinner/organic solvent harmless to copper...slightly oilier, so it doesn't result in that dried-out look.

As others have already said, acetone can't fix damage and can expose it.

brg5658 - I have witnessed red/purple/blue from MS70 on circulated copper, never from acetone.
Lance. >>



Lance, my main negative experience was on an 1812 Provincial token from Birmingham and South Wales that this happened to. It wasn't an expensive coin, but it was most definitely not this deep (unnatural) red before I did an acetone rinse. It's very possible that it was some other chemical on the surface, but the coin now has very dark red stains on the parts of the token that before the acetone treatment were not as such. I was also told acetone was completely fine, and in my case, it clearly wasn't.

The token doesn't exhibit any even remote evidence of having been treated with MS70, and I know the difference between the bluish/purple tones that MS70 can impart.

Note the blotchy red areas:

lkeigwin

Right. I don't believe acetone caused it. I think it exposed it.

Interesting token. My ancestors came from Wales long ago (really in Cornwall...a place called Mousehole). But I don't know anything about their coinage.
Lance.

Flatwoods

The only time I have had problems is with coins/medals that have been messed with or had surface contaminants.
There is one medal floating around on Ebay now that I bought.
I knew something was fishy about it even though it looked passable.
When rinsed in acetone large areas of color came off.
I returned it and it was back on Ebay promptly looking as good as new.

Pokermandude

Thanks for the replies.

In my own experience with acetone on red and red/brown copper, I've had pieces turn out fine. But others have turned shades of green, pink and light purple that were most definitely not there before. Even on pieces I am sure hadn't been cleaned.

I'll try acetone and report back with the results. Even a discoloured coin would be favourable to this heavy and active PVC contamination.

Broadstruck

That green growth is Verdigris not PVC and will not come off with a Acetone rinse.

You'll have to soak this in mineral oil instead.

Pokermandude

<< <i>That green growth is Verdigris not PVC and will not come off with a Acetone rinse.

You'll have to soak this in mineral oil instead. >>



Looking more closely at it, I think you might be right that it is Verdigris rather than PVC. Although it's possible that it has both issues.

Assuming it has both issues, I am assuming it would be better to treat the Verdigris firs with mineral oil, and then acetone for the PVC if there is any, rather than acetone before mineral oil. Right?

Broadstruck

<< <i>

<< <i>That green growth is Verdigris not PVC and will not come off with a Acetone rinse.

You'll have to soak this in mineral oil instead. >>



Looking more closely at it, I think you might be right that it is Verdigris rather than PVC. Although it's possible that it has both issues.

Assuming it has both issues, I am assuming it would be better to treat the Verdigris firs with mineral oil, and then acetone for the PVC if there is any, rather than acetone before mineral oil. Right? >>



There's no PVC growth on this example and avoid using acetone on this cent as it would have a major dried out lifeless look after submersion.

BAJJERFAN

<< <i>If you use acetone on it, and some of the "red/brown" areas become a dark red almost purple, then don't be surprised. Acetone is not "supposed" to do odd things to copper color-wise, but from many personal experiences, I can attest that it does. Acetone bathe at your own risk on red/brown or brown copper. >>



An alternative solvent might be tetrahydrofuran aka THF if one can get it.

Pokermandude

After about 40 days soaking in mineral oil, most of the green did eventually come off. There are a few stubborn pieces which haven't yet dissipated, but I think eventually they too might come off with a longer soak.

As I suspected, there was a pretty nice looking coin underneath the green gunk!

LindeDad

originalisbest

Looks like a bigtime save -- the coin is much better off for it -- congrats, and glad the mineral oil worked out well!

Icollecteverything

That looks much better now.

sparky64

Your patience is working well.
Nice coin.

Flatwoods

Very nice!
I didn't think the verdigris on the E would come off that well.
Sometimes it do and sometimes it don't.

lostincoins

What about verdiclean/care products?

Text

SamByrd

<< <i>If you use acetone on it, and some of the "red/brown" areas become a dark red almost purple, then don't be surprised. Acetone is not "supposed" to do odd things to copper color-wise, but from many personal experiences, I can attest that it does. Acetone bathe at your own risk on red/brown or brown copper. >>



my exact experience on red copper as well in some instances.

ricko

The mineral oil has worked well.... olive oil will do the same thing..usually a tad faster... use EVOO.... Any deleterious phenomena observed after an acetone bath is due either to what was on the surface or below what you want removed. Acetone will not affect copper.... (have a cent that was kept in a bottle of acetone for 26 months.... no visible difference). Cheers, RickO

Broadstruck

<< <i>What about verdiclean/care products?

Text >>



I wouldn't recommend using that on any coin worth more the this product as it will change the color.

Broadstruck

<< <i>After about 40 days soaking in mineral oil, most of the green did eventually come off. There are a few stubborn pieces which haven't yet dissipated, but I think eventually they too might come off with a longer soak.

As I suspected, there was a pretty nice looking coin underneath the green gunk! >>