Green rot on gold

[ageka]

I have three new gold sovereings

Definition of new = 1957 and later

All three have dozens of green spots on them

I have no access to MS 70 what should I try ?

The spots are only visible under 10X magnification

[ageka]

Close up of green spots

Sovereign_1958_L_2_green3.BMP

[Art]

I don't have my book handy. What's the composition of the sovereign.

 

Gold plus perhaps copper...

[28Plain]

if you've eliminated PVC scuzz as the culprit, it's probably copper bloom of some sort. Since you were willing to use MS70, you should be as comfortable with Tarnex which has the same thiosulphite composition as MS70 but with none of the useless, film leaving surfactant that MS70 contains.

 

Dunk them in Tarnex for about 90 seconds or so and the copper preferential thiosulphate will attack the green boogers and leave you with a cool looking coin again. Don't forget to rinse under running water, warm or cold for several seconds after the dunk.

[Ætheling]

I don't have my book handy. What's the composition of the sovereign.

 

Gold plus perhaps copper...

 

 

1816-present = 22ct gold, rest is copper. So .917 Au.

 

Except some 1859's which are 22ct Au, with the remainder comprising of Cu and As.

[ageka]

Thank you for the advise

One of the coins was MS62 like

the lowest rank of the three

So I dunked it in acetone and rubbed it with a surgical glove on

The green spots just rub off

So it must be a mono molecular layer of coppersulfate or copperchloride or whatever because the saltcolor on gold changes

like black silversulfide shows red etc

I am going to let the next one sit in acetone without touching for an hour

and see what happens

[Ætheling]

Thank you for the advise

One of the coins was MS62 like

the lowest rank of the three

So I dunked it in acetone and rubbed it with a surgical glove on

The green spots just rub off

So it must be a mono molecular layer of coppersulfate or copperchloride or whatever because the saltcolor on gold changes

like black silversulfide shows red etc

I am going to let the next one sit in acetone without touching for an hour

and see what happens

 

 

If it's CuSO4 then wouldn't just washing it in water remove it? Afterall it's water soluble. Me thinks it must be chloride or carbonate, which i forget if they are soluble or not.

[Ætheling]

If it's CuSO4 then wouldn't just washing it in water remove it? Afterall it's water soluble.

 

 

Mind you having said that i've just remembered i once chucked a copper plate penny in some CuSO4 and it turned green quite quick, sticking that in water didn't get it off. So maybe it'd be so well bonded to the surface that it wouldn't shift?

[GDJMSP]

Looks like verdigris to me - get some biox.

[ageka]

Whatever it was it came off after 60 minutes in acetone

[28Plain]

Congrats. It was likely just some degraded PVC.

[ageka]

Congrats.  It was likely just some degraded PVC.

 

You were right with your first suggestion about pvc

 

I made a mistake in guessing how long I had those coins

Turns out they have been sitting in a bankvault in 2X2's for 35 years

However the older sovereigns George and Edwards were not affected

So it must be a combination of surface copper and like you say pvc plasticizer

 

Normally anything acetone will dissolve only takes a minute so this is my

first experience were I needed such a long time

and also my first experience with pvc problems on gold

[28Plain]

I've had PVC gunk on lots of silver but never on gold. Still, it can happen. With gold there's less chance of any attack on the surface since gold isn't a reactive metal like silver is.

 

BTW, is a young head half sovereign in VF usually worth only bullion value?

[ageka]

I've had PVC gunk on lots of silver but never on gold.  Still, it can happen.  With gold there's less chance of any attack on the surface since gold isn't a reactive metal like silver is.

 

  BTW, is a young head half sovereign in VF usually worth only bullion value?

 

What I showed was a full sovereing of Elisabeth two uncirculated starts in 1957

( is that what you mean by a young head or do you mean young Victoria ? )

In Belgium all coins on the national list can be bought in XF or better

for like 2% over melt at any exchange agent

Less then XF should not be sold unless a real numismatic

Attached the leading exchange agent that publishes his prices continuously on teletext and internet for the other exchange agents to use

The one I know will add one euro per coin

The prices listed for double eagles forget them ; they only buy and then sell to americans

 

http://www.gold4ex.be/servlet/javaparser.c...st_or_new&lg=nl

[28Plain]

Yes, I meant Victoria. Thanks for the link.

[ageka]

Yes, I meant Victoria.  Thanks for the link.

 

Officially they have the young head with knight slaying dragon reverse

in XF for melt plus 2 % but I would not count on it

because these guys are visited monthly by one of the leading British ebayers

and regularly by all kinds of american dealers

I phoned twice to buy a Double Eagle and twice got the answer that an american

had bought the complete inventory

That may be their standard answer

[28Plain]

I buy all of my world gold from a few small timers I trust, usually. Getting hold of a tough type may send me to Camino Coin sometimes, but generally, I get a piece or two a month from a little hole in the wall shop in the combat zone , downtown in Richmond.

 

I may try your source pretty soon.

[ageka]

I buy all of my world gold from a few small timers I trust, usually.  Getting hold of a tough type may send me to Camino Coin sometimes, but generally, I get a piece or two a month from a little hole in the wall shop in the combat zone , downtown in Richmond.

 

  I may try your source pretty soon.

 

He may refuse selling by mail

On the other hand this guy sells fully insured by mail

His prices however are not allways up to date

So email for price and availability and conditions

 

http://www.eurogold.be/UK/main.htm

[28Plain]

Thanks. I just got an 1890 half sovereign from a local gold buyer for BV+2%. That was my first jubilee gold.

[ageka]

Thanks.  I just got an 1890 half sovereign from a local gold buyer for BV+2%.  That was my first jubilee gold.

 

That looks like a good deal

Any sovereign or half before early 1900's is difficult to get for that price

Any chance you could post a scan or picture ?

[28Plain]

That looks like a good deal

Any sovereign or half before early 1900's is difficult to get for that price

Any chance you could post a scan or picture ?

 

If my wife helps me install the scanner pretty soon, I may be able to start providing some images. I'm an ignorant savage when it comes to computers. Any chore that doesn't require a hammer leaves me scratching my head and grunting. ;-)