My Latest Acquisition

[Sword]

I did a search and came across an article saying that the method of silver plating by dipping into acid has been done since Roman time.

"The Roman moneyers had discovered that copper is readily etched away by certain acids and corrosive salts that will leave silver untouched. A coin blank was made in the regular way of an alloy containing about 5% silver, sometimes less. The blank was then dipped in a "pickle" solution of corrosive salts and acid. Sometimes the blank was heated and dipped again to speed up the process. The copper was dissolved out, leaving a microscopically thin layer of pure, spongy silver on the surface of the blank. When the blank was struck up with the emperor's portrait and the design on the reverse, the sponge silver was flattened down and spread across the surface of the coin, leaving a beautiful, brilliant silvery finish on the coin. This soon wore off in circulation, though, leaving an ugly gray, brown, white, or black splotchy surface on the coin."

http://jaysromanhistory.com/romeweb/engineer/art15.htm

 

[Rob]

Part of the problem is the difference in melting points between silver and copper, the latter being about 100 degrees higher. Unless the pot temperature is significantly higher than the melting point of silver in order to melt the copper and form the alloy, you run the risk of some coins taken from the top of the liquid which are considerably purer than spec whilst being left towards the end of the batch with a very debased mix having a distinctly coppery flavour. However, as all the metal was accounted for, it was necessary to strike the last coins of the batch from the residue and pickle the surfaces as in the post above.

The Bristol halfcrown below shows the brown/red tinges of a flan that is mostly copper to good effect.

Edited December 5, 2017 by Rob

[Peckris]

13 hours ago, IanB said:

The greyish, pinkish patches spoken about earlier that appears on silver is called firestain. It occurs when silver is heated usually during the annealing process. Oxidisation takes places reacting with the copper used in the silver resulting in these patches forming on the surface.

This can sometimes be covered by heavy silver plating but is more often polished away. In general acid will not remove it unless the silver is left in so long that it starts to dissolve.

Ok, fair enough. But the issue with - e.g. - 1925 halfcrowns is that the pinky-brown patches appear only on fairly well-worn examples, never on BU examples. Here are two from the Bay (the higher grade halfcrown has a problem with 'green' - a common problem! - but not with brown, unlike the more worn one):

[IanB]

Don't know the mintage figures for these coins but not every coin will have fire stain. It may still be there on a BU coin, but is lost in the brightness of the metal and only become visible when the metal loses its shine and becomes matt through wear.

A way of spotting firestain is to place a piece of tracing paper in contact with the metal, this diffuses the light and reflections and the stain appears as a grey patch through the tracing paper.

As I said not every coin will have firestain, it depends on how the metal was heated during production. It may also have been polished out prior to stamping.

I have attached an article that talks about fire scale, another name for the same thing.

http://www.silversmithing.com/1fire.htm

Edited December 5, 2017 by IanB

[Peckris]

Ian, thanks for that - an educational if somewhat technical read!

The one problem is that the article says that firestain is random, i.e. not only on which (coins) it might appear, but also whereabouts. However, the pattern of 'brown/pink' you see on that halfcrown above, is absolutely typical; in other words if it is seen, it's pretty much always in the same places - the edges of the shield and the parts of the garter where most wear takes place. Similarly, it's usually the same points on the obverse, i.e. the highest parts of the portrait, spreading as it wears more.

It's almost as if the copper lies deeper, and is gradually uncovered by wear. But I'm no scientist.

[Rob]

17 minutes ago, Peckris said:

Ian, thanks for that - an educational if somewhat technical read!

The one problem is that the article says that firestain is random, i.e. not only on which (coins) it might appear, but also whereabouts. However, the pattern of 'brown/pink' you see on that halfcrown above, is absolutely typical; in other words if it is seen, it's pretty much always in the same places - the edges of the shield and the parts of the garter where most wear takes place. Similarly, it's usually the same points on the obverse, i.e. the highest parts of the portrait, spreading as it wears more.

It's almost as if the copper lies deeper, and is gradually uncovered by wear. But I'm no scientist.

I think the higher concentrations are at a uniform depth, i.e. any blanching by whatever means would go to a similar depth across the surface, but only the high points suffer exposure as they are the only parts that get worn. The coin has to be in a fairly dire state, say VF or below before you see any appreciable wear to the protected areas.

[zookeeperz]

Bought this . I love the patina on this coin. Looks like a Hypo coin which I would guess is a scarce thing on 1950 pennies?

 

[zookeeperz]

And this 1903 florin nicer than the stock pic. I will update when it arrives 

 

[jelida]

1 hour ago, zookeeperz said:

Bought this . I love the patina on this coin. Looks like a Hypo coin which I would guess is a scarce thing on 1950 pennies?

 

Yes, I too love a dark patina where the surfaces are good and have that lustrous sheen.

I don’t know if they still used hypo as late as 1950, can’t say I’ve confidently seen it post 1946.

Jerry

[zookeeperz]

1950 Penny  Arrived this morning. Actually the picture apart from almost being same colour in the hand its much much nicer and is completely uniform in a very satiny bright luster and chestnut patina. I have never seen one like this before. Its stunningly good

 

[zookeeperz]

Also in santas post bag the 1903 Florin

 

[Leo]

9 hours ago, zookeeperz said:

1950 Penny  Arrived this morning. Actually the picture apart from almost being same colour in the hand its much much nicer and is completely uniform in a very satiny bright luster and chestnut patina. I have never seen one like this before. Its stunningly good

 

Lovely chocolate colour!

[UPINSMOKE]

Just received my latest coin for the new year 2018  . A 1898 Threepence. I now am in a bit of a quandary as I already have another one of the same year. I need some help deciding which to keep and which to move on, or should I keep both 

If you could help please see pictures below. Any help in making a decision would be appreciated.

Original Coin

Latest Arrival

 

[Rob]

Top one. The bottom one has been cleaned.

[Stuntman]

Totally agree.  The top one is very nice.

[UPINSMOKE]

3 hours ago, Rob said:

Top one. The bottom one has been cleaned.

 

1 hour ago, Stuntman said:

Totally agree.  The top one is very nice.

Thanks guys. I am still buying some crap.  How do you tell when a coin has been cleaned, it looked fine in their pictures. Still cannot get it right 

Edited January 5, 2018 by UPINSMOKE

[Peter]

3 minutes ago, UPINSMOKE said:

 

Thanks guys. I am still buying some crap.  How do you tell when a coin has been cleaned, it looked fine in their pictures. Still cannot get it right 

You can return it for a refund surely....The latest arrival is covered in hairlines.Was it an EBAY purchase? 

[Nonmortuus]

1 hour ago, UPINSMOKE said:

 

Thanks guys. I am still buying some crap.  How do you tell when a coin has been cleaned, it looked fine in their pictures. Still cannot get it right 

Look at the fields. If the have the odd mark chances are they are from circulation or maybe bag marks. If the fields look like a wire brush has been across them it stands a damn good chance of having been cleaned. Don't beat yourself up, I'm pretty sure most people will have bought a cleaned coin at some point. Either return it or keep it as a reference point as a cleaned coin.

[Stuntman]

^^^ Yep.  And definitely don't beat yourself up.  The coin probably looks fairly OK in hand but the photos are as clear as day, it hits you straight away.

I certainly have at least 4 coins that have definitely been cleaned or polished and probably a few more!

[UPINSMOKE]

2 hours ago, Peter said:

You can return it for a refund surely....The latest arrival is covered in hairlines.Was it an EBAY purchase? 

Hi Peter yes was an eBay purchase not that expensive just thought I would take a chance. My fault entirely, will put it down to experience and move on.

 

43 minutes ago, Nonmortuus said:

Look at the fields. If the have the odd mark chances are they are from circulation or maybe bag marks. If the fields look like a wire brush has been across them it stands a damn good chance of having been cleaned. Don't beat yourself up, I'm pretty sure most people will have bought a cleaned coin at some point. Either return it or keep it as a reference point as a cleaned coin.

Thanks Nonmortuus  for your comments, by the way I wish I knew your first name I am hopeless at remembering first names.

 

15 minutes ago, Stuntman said:

^^^ Yep.  And definitely don't beat yourself up.  The coin probably looks fairly OK in hand but the photos are as clear as day, it hits you straight away.

I certainly have at least 4 coins that have definitely been cleaned or polished and probably a few more!

Thanks Stuntman for your input very welcome, and again sorry forgot your first name as well. 

I will go with the majority and keep the first one thanks.

While we are on the subject of cleaning I would value you opinions on the other coin I have just purchased below. Would be interested in what you think of this one another 1898 3d.

[Unwilling Numismatist]

I'd be most happy with the 1898, but then my standards haven't risen quite to the dizzy heights of everyone elses (yet..)

[1949threepence]

Top one, Mick. No question.

Agree with the other replies.

 

[UPINSMOKE]

1 minute ago, Unwilling Numismatist said:

I'd be most happy with the 1898, but then my standards haven't risen quite to the dizzy heights of everyone elses (yet..)

Well it could be yours for a small fee 

[Unwilling Numismatist]

2 minutes ago, UPINSMOKE said:

Well it could be yours for a small fee 

I'll need to sell some more junk first   -

[UPINSMOKE]

2 minutes ago, 1949threepence said:

Top one, Mick. No question.

Agree with the other replies.

 

Thanks again for your help with this. Again forgetting first names  I wish everyone would add their first names to there posts, I would then get them in my head. Any thoughts on my last coin images please.