PVC on Gold?

erwindoc

What is going on at the rim of this coin? Is it just dark toning or is it PVC damage?

lcoopie

Guess, pvc

PerryHall

Dirt or copper spotting. I don't think PVC will turn gold black like that. I don't think it's a big deal and it probably isn't worth the cost of conservation.

ricko

PVC will not affect gold....It likely is a transfer from something which the coin has come in contact with. Cheers, RickO

ianrussell

PVC can still appear on gold coins - on the surface or perhaps the alloy mix. Not as common as on copper/silver coins.

• Ian

fivecents

I used to submit a lot of modern gold commems to PCGS to sell the PR/MS70's. Back when PCGS made everyone submitting coins use poly bags. You had to put the coins in the poly bags and then put the poly bag in the mylar 2 x 2 flip. Everyone packed coins off to PCGS this way.
Maybe around 2002 (?) PCGS sent out fliers to PCGS members saying to stop using the poly-bags. The reason was the the poly bags were leaving a PVC haze on the coins.
I noticed that almost all of my registry set PR/MS certifed gold $5 commems had started turning purple. I called PCGS about it and was told that the toning was from the coins being submitted in the poly bags. It had something to do with the sonic sealing process activating the PVC haze . Which turned the gold purple.
If another forum member remembers and could verify my story. I know this sounds far fetched, but it's true.

Broadstruck

It's PVC growth not damage.

Gold is inert to it so it's not something that's ever critical for removal.

NGC should take care of this whenever you feel like having it remedied.

PerryHall

@fivecents said:
I used to submit a lot of modern gold commems to PCGS to sell the PR/MS70's. Back when PCGS made everyone submitting coins use poly bags. You had to put the coins in the poly bags and then put the poly bag in the mylar 2 x 2 flip. Everyone packed coins off to PCGS this way.
Maybe around 2002 (?) PCGS sent out fliers to PCGS members saying to stop using the poly-bags. The reason was the the poly bags were leaving a PVC haze on the coins.
I noticed that almost all of my registry set PR/MS certifed gold $5 commems had started turning purple. I called PCGS about it and was told that the toning was from the coins being submitted in the poly bags. It had something to do with the sonic sealing process activating the PVC haze . Which turned the gold purple.
If another forum member remembers and could verify my story. I know this sounds far fetched, but it's true.

@fivecents said:
I used to submit a lot of modern gold commems to PCGS to sell the PR/MS70's. Back when PCGS made everyone submitting coins use poly bags. You had to put the coins in the poly bags and then put the poly bag in the mylar 2 x 2 flip. Everyone packed coins off to PCGS this way.
Maybe around 2002 (?) PCGS sent out fliers to PCGS members saying to stop using the poly-bags. The reason was the the poly bags were leaving a PVC haze on the coins.
I noticed that almost all of my registry set PR/MS certifed gold $5 commems had started turning purple. I called PCGS about it and was told that the toning was from the coins being submitted in the poly bags. It had something to do with the sonic sealing process activating the PVC haze . Which turned the gold purple.
If another forum member remembers and could verify my story. I know this sounds far fetched, but it's true.

I thought poly sleeves were polyethylene which is inert.

cinclodes

@Broadstruck said:
Gold is inert to it so it's not something that's ever critical for removal.

Gold is indeed inert, but what about the gold alloy? Is it possible for the 10% copper to react? I took several chemistry courses 40+ years ago, but I don't know the answer.

Cougar1978

Appears to be PVC damage - coin needs dip / conservation. Don’t consider sellable as is.

Oldhoopster

As the plasticizer in the PVC breaks done, one of the decomposition products is Hydrochloric Acid. As others have said, Gold will not react with HCl, but this is an alloy. Will HCl react with the alloy??? I can't say for certain, but I would not want to find out the hard way. At minimum, the green residue is unsightly and I certainly would not purchase a slabbed gold coin with that on it.

Insider2

Don't have time to reply in full. The same green-brown scum that accumulates on copper, brass, and bronze can be found on gold. I'll post some images. It comes right off. The actual black stuff is different.

Cougar1978

I wonder if dipping would get that off. That really looks bad. At the very least you would probably have to work it with dip soaked Q tip.

Catbert

@Cougar1978 said:
I wonder if dipping would get that off. That really looks bad. At the very least you would probably have to work it with dip soaked Q tip.

The prongs look worse.

ReadyFireAim

This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

lcoopie

@ReadyFireAim said:
This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

I’d look for a slight whitish haze

jwitten

@ReadyFireAim said:
This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

Clearly only worth melt now... let me know if it's for sale

Insider2

As stated by another member, what you are seeing is a reaction to the copper in the gold alloy. This comes off easily but a tiny pinkish spot will remain.

@Cougar1978 said:
I wonder if dipping would get that off. That really looks bad. At the very least you would probably have to work it with dip soaked Q tip.

@ReadyFireAim said:
This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

The entire coin has a PVC haze.

ReadyFireAim

@Insider2 said:
The entire coin has a PVC haze.

Interesting.
It was reconsidered for a + in September of last year and re-slabbed.

Maybe I should send it in for conservation.

Catbert

@ReadyFireAim Respectfully, do you now value CAC’s opinion on gold?

ReadyFireAim

@Catbert said:
@ReadyFireAim Respectfully, do you now value CAC’s opinion on gold?

I'm finding them useful.
Mostly by keeping big money away from the coins I'm interested in.

thefinn

Jeweluster dip won't remove this Dichloromethane on a Q-tip rolled over it should get it off without leaving a trace.

NSP

@cinclodes said:

@Broadstruck said:
Gold is inert to it so it's not something that's ever critical for removal.

Gold is indeed inert, but what about the gold alloy? Is it possible for the 10% copper to react? I took several chemistry courses 40+ years ago, but I don't know the answer.

Very good question. When alloys are involved, something called “selective leaching” (also known as “dealloying”) comes into play. Selective leaching is a big concern for brasses, in which zinc is selectively leached from the copper-zinc alloy. This particular type of selective leaching is given the fancy name “dezincification.”

In an alloy, there are at least two different metals in a solid solution (let’s assume there are only two metals to simplify things). One metal will be more noble (less active) and the other metal will be less noble (more active). If there is enough of the less noble metal in the alloy and the alloy is exposed to the correct corrosive environment, the less noble element will be selectively leached out of the alloy. This will leave behind a “spongy” structure made out of the more noble metal that’s left behind. However, if the amount of the less noble metal present in the alloy is small enough, the more noble metal will be able to “keep” the less noble metal from being selectively leached. This threshold is called the “parting limit” for the alloy. For brass (copper and zinc), the parting limit is about 15% zinc. That is to say, if the brass is less than 15% zinc, the copper will be able to “keep” the zinc in the alloy and selective leaching will be prevented.

The mechanism by which the copper “keeps” the zinc in place is still unknown and is up for debate. There are several different theories that have been proposed, some more appropriate for certain alloys than others, but nobody knows for sure.

As for a 90/10 gold/copper alloy, I would be inclined to think that the parting limit would be higher than 10% copper, but I don’t know for sure (a cursory google search has not found the parting limit for a gold/copper alloy). With that in mind, I doubt that the HCl would be able to selectively leach the copper. However, nothing in the world of corrosion is guaranteed, and I’m sure there is always an exception to the rule.

This short article is a good source for more information: https://www.corrosionclinic.com/types_of_corrosion/dealloying_selective_leaching_graphitic_corrosion.htm

ricko

@NSP....Thank you for that informative post. I had forgotten about 'parting limit' information (many, many years since my metallurgical training)...That link is great and I will use it to refresh my knowledge bank. Cheers, RickO

asheland

@ReadyFireAim said:
This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

I've found that holding the coin under a light at an angle especially fluorescent it will show up...

ReadyFireAim

@asheland said:
I've found that holding the coin under a light at an angle especially fluorescent it will show up...

I'm finally seeing it when rotating it at about 30 degrees or less.

It's going off for conservation tomorrow.
I really liked the toning on this one but it looks like it's under the PVC and will probably be destroyed.
Maybe JA will like it after PCGS turns it back into a something that looks like an AGE

BAJJERFAN

@cinclodes said:

@Broadstruck said:
Gold is inert to it so it's not something that's ever critical for removal.

Gold is indeed inert, but what about the gold alloy? Is it possible for the 10% copper to react? I took several chemistry courses 40+ years ago, but I don't know the answer.

Yes, that would be the source of the PVC damage. PVC reacting with the copper that is in many gold coins.

BAJJERFAN

@Insider2 said:
As stated by another member, what you are seeing is a reaction to the copper in the gold alloy. This comes off easily but a tiny pinkish spot will remain.

@Cougar1978 said:
I wonder if dipping would get that off. That really looks bad. At the very least you would probably have to work it with dip soaked Q tip.

@ReadyFireAim said:
This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

The entire coin has a PVC haze.

Here I think that PVC means Pretty Valuable Comment.

ReadyFireAim

I'm going to post a TrueView of before conservation & after.
Here is before....

I'll also let everyone know how much it cost and other details.
It was sent out today registered mail (Express Gold Shield service marked on package)

erwindoc

What don't you like about it that needs conservation?

ReadyFireAim

@erwindoc said:
What don't you like about it that needs conservation?

There is a white splotchy haze almost all over the coin that looks like mold.
It's only visible from an angle but I don't like that it's there.

I thought PVC was green but I guess I was wrong.
The slab looks like a petri dish w/ fungus growing all over it...Yuck!

PerryHall

@ReadyFireAim said:

@erwindoc said:
What don't you like about it that needs conservation?

There is a white splotchy haze almost all over the coin that looks like mold.
It's only visible from an angle but I don't like that it's there.

That sounds more like putty than PVC.

ReadyFireAim

looks kinda like this but the splotches are larger.

Insider2

The True View is beautiful! Looks like a completely different coin.

cinclodes

@NSP said:

@cinclodes said:

@Broadstruck said:
Gold is inert to it so it's not something that's ever critical for removal.

Gold is indeed inert, but what about the gold alloy? Is it possible for the 10% copper to react? I took several chemistry courses 40+ years ago, but I don't know the answer.

Very good question. When alloys are involved, something called “selective leaching” (also known as “dealloying”) comes into play. Selective leaching is a big concern for brasses, in which zinc is selectively leached from the copper-zinc alloy. This particular type of selective leaching is given the fancy name “dezincification.”

In an alloy, there are at least two different metals in a solid solution (let’s assume there are only two metals to simplify things). One metal will be more noble (less active) and the other metal will be less noble (more active). If there is enough of the less noble metal in the alloy and the alloy is exposed to the correct corrosive environment, the less noble element will be selectively leached out of the alloy. This will leave behind a “spongy” structure made out of the more noble metal that’s left behind. However, if the amount of the less noble metal present in the alloy is small enough, the more noble metal will be able to “keep” the less noble metal from being selectively leached. This threshold is called the “parting limit” for the alloy. For brass (copper and zinc), the parting limit is about 15% zinc. That is to say, if the brass is less than 15% zinc, the copper will be able to “keep” the zinc in the alloy and selective leaching will be prevented.

The mechanism by which the copper “keeps” the zinc in place is still unknown and is up for debate. There are several different theories that have been proposed, some more appropriate for certain alloys than others, but nobody knows for sure.

As for a 90/10 gold/copper alloy, I would be inclined to think that the parting limit would be higher than 10% copper, but I don’t know for sure (a cursory google search has not found the parting limit for a gold/copper alloy). With that in mind, I doubt that the HCl would be able to selectively leach the copper. However, nothing in the world of corrosion is guaranteed, and I’m sure there is always an exception to the rule.

This short article is a good source for more information: https://www.corrosionclinic.com/types_of_corrosion/dealloying_selective_leaching_graphitic_corrosion.htm

Thanks for a very interesting and informative post. I would guess that the parting limit would depend on what the coin is being exposed to. I would agree that it must be greater than 10% copper under most conditions as is evidenced by the pristine condition of the 1857-S double eagles that were recovered from the S.S. Central America.

MFeld

@cinclodes said:

@NSP said:

@cinclodes said:

@Broadstruck said:
Gold is inert to it so it's not something that's ever critical for removal.

Gold is indeed inert, but what about the gold alloy? Is it possible for the 10% copper to react? I took several chemistry courses 40+ years ago, but I don't know the answer.

Very good question. When alloys are involved, something called “selective leaching” (also known as “dealloying”) comes into play. Selective leaching is a big concern for brasses, in which zinc is selectively leached from the copper-zinc alloy. This particular type of selective leaching is given the fancy name “dezincification.”

In an alloy, there are at least two different metals in a solid solution (let’s assume there are only two metals to simplify things). One metal will be more noble (less active) and the other metal will be less noble (more active). If there is enough of the less noble metal in the alloy and the alloy is exposed to the correct corrosive environment, the less noble element will be selectively leached out of the alloy. This will leave behind a “spongy” structure made out of the more noble metal that’s left behind. However, if the amount of the less noble metal present in the alloy is small enough, the more noble metal will be able to “keep” the less noble metal from being selectively leached. This threshold is called the “parting limit” for the alloy. For brass (copper and zinc), the parting limit is about 15% zinc. That is to say, if the brass is less than 15% zinc, the copper will be able to “keep” the zinc in the alloy and selective leaching will be prevented.

The mechanism by which the copper “keeps” the zinc in place is still unknown and is up for debate. There are several different theories that have been proposed, some more appropriate for certain alloys than others, but nobody knows for sure.

As for a 90/10 gold/copper alloy, I would be inclined to think that the parting limit would be higher than 10% copper, but I don’t know for sure (a cursory google search has not found the parting limit for a gold/copper alloy). With that in mind, I doubt that the HCl would be able to selectively leach the copper. However, nothing in the world of corrosion is guaranteed, and I’m sure there is always an exception to the rule.

This short article is a good source for more information: https://www.corrosionclinic.com/types_of_corrosion/dealloying_selective_leaching_graphitic_corrosion.htm

Thanks for a very interesting and informative post. I would guess that the parting limit would depend on what the coin is being exposed to. I would agree that it must be greater than 10% copper under most conditions as is evidenced by the pristine condition of the 1857-S double eagles that were recovered from the S.S. Central America.

Keep in mind that the 1857-S $20's were likely conserved to varying extents.

topstuf

@MFeld said:

Keep in mind that the 1857-S $20's were likely conserved to varying extents.

WHAT? You mean bright, shiny and almost perfect isn't what's meant by "Shipwreck effect?"

ReadyFireAim

@Insider2 said:
The entire coin has a PVC haze.
@Insider2 said:
The True View is beautiful! Looks like a completely different coin.

And that folks, is what you call experience.
Knowing what a coin looks like without even seeing it is a pretty good trick.

Insider2

@ReadyFireAim said:

@Insider2 said:
The entire coin has a PVC haze.
@Insider2 said:
The True View is beautiful! Looks like a completely different coin.

And that folks, is what you call experience.
Knowing what a coin looks like without even seeing it is a pretty good trick.

Actually, "originality" is a quick study with a good mentor.

ReadyFireAim

Conservation finished.
I was worried about a loss of toning but it looks great!
Shipped today.
Will let you know more when I get it.

Also...It stayed the same grade but got a new number (MS65+)

Broadstruck

@ReadyFireAim said:
Conservation finished.
I was worried about a loss of toning but it looks great!
Shipped today.
Will let you know more when I get it.

Also...It stayed the same grade but got a new number (MS65+)

Could you point out where the PVC growth was?

I keep glancing at both photos and think it must be hiding behind Waldo?

Thanks in advance!

ReadyFireAim

@Broadstruck said:
Could you point out where the PVC growth was?
I keep glancing at both photos and think it must be hiding behind Waldo?

They are hazy/moldy looking splotches that aren't very visible form straight on.
At an angle it's quite disturbing.

I have one more coin with the same problem that I got from a dealer who probably thought he was putting one over on me.
I think I'll have the last laugh when it upgrades & doubles in price
We shall see

Insider2

@asheland said:

@ReadyFireAim said:
This one came back from CAC denied & with this red sticker.
I can't find the PVC even though I looked everywhere.

The OP's coin does look like PVC but It also looks like an easy fix.

I've found that holding the coin under a light at an angle especially fluorescent it will show up...

There is a very good reason florescent light is not recommended for examining coins! However, if you are not looking at your coins with florescent light in addition to incandescent light...

ReadyFireAim

It took a long time for the new picture to be linked w/ coin facts.
Here it is now and you can see that some of the toning is gone but so is the PVC.
Price was $80 for the service. Quite reasonable I think.

Anyway....Before pic of the coin I just sent in for resto (same problem...PVC haze)

Will update after I get it back.

Broadstruck

@ReadyFireAim said:
It took a long time for the new picture to be linked w/ coin facts.
Here it is now and you can see that some of the toning is gone but so is the PVC.
Will update after I get it back.

Please let us know if it actually looks different in hand as a acetone bath to remove PVC on gold should not change anything. I bet the 1914-S was just photographed by different photographers with a different technique, camera, lens, settings, etc.

ReadyFireAim

@ReadyFireAim said:

Will update after I get it back.

Coin done but not in hand yet...New pic & number

It also went from 65 to 65+
Small jump in value from what I payed, $3000, to $3650 will more than cover the resto bill & shipping.
Thought I had a shot at 66 but I'm fine w/ 65+