Charles II tin farthing

[Red Riley 2]

As a diversion from adverts about viagra and adult movies, I thought I would post something about coins...

Some years ago I acquired a rather odd tin farthing. Condition is pretty good for one of these dreadful coins - even the date on the edge is just about readable.

The problem with it is, that the tin plug does not seem to penetrate as far as the reverse which, as a consequence is just plain tin. The plug itself also appears somewhat shallower than usual. From looking at other tin coins, the plug usually appears much larger on the obverse than the reverse, and is therefore tapered in shape. Has anyone else come across this before, or has any views on the subject.

[Rob 3,152]

As a diversion from adverts about viagra and adult movies, I thought I would post something about coins...

Some years ago I acquired a rather odd tin farthing. Condition is pretty good for one of these dreadful coins - even the date on the edge is just about readable.

The problem with it is, that the tin plug does not seem to penetrate as far as the reverse which, as a consequence is just plain tin. The plug itself also appears somewhat shallower than usual. From looking at other tin coins, the plug usually appears much larger on the obverse than the reverse, and is therefore tapered in shape. Has anyone else come across this before, or has any views on the subject.

I remember Colin Cooke saying he had an example with the plug on one side only. He also had one with 2 plugs.

Just thinking off the top of my head, it is possible that counterfeits could be made a lot more efficiently by making a small depression as part of the casting mould and hammering in a small piece of copper. I don't know if they were made in this way, but it would be easy. I have a counterfeit tin halfpenny where there is the shape of the plug in the detail, but no actual plug in place and of course the edge doesn't have an inscription. It is also obviously cast.

[Red Riley 2]

Thanks Rob,

It is an odd one, but looks pretty genuine and due to the existence of faily clear edge lettering and lustre, clearly has not been cast. If it is a modern forgery, it is an extremely good one as everything about it, apart from the plug looks 'right'. Has anybody come across a forged tin coin?

[scottishmoney 29]

I know that coin is off topic, but it is rather sexier in it's coindition than many of the stupid ads I had to nuke this week.

These things were made to help out the tin miners and keep them employed weren't they?

[DaveG38 405]

I am pretty sure that Red Riley is quite correct about the taper. Colin Cooke did indeed have a coin where the plug was missing, but only went part of the way through. The coin was a 1689 tin farthing, which is now in my collection - pictures of it are still on the CC website. The plug was roughly rectangular in shape, and tapered as it went into the coin, but it didn't go all the way through.

There is also another 1689 on the CC website, where the plug is mssing, and looking at the obverse and reverse photos, it seems to me that the plug was wedge shaped when put in by the mint.

Hope this helps.

DaveG38

[scottishmoney 29]

These things are contemporary to the Newby Halfpennies and Farthings which circulated in New Jersey during the 1670's, they are alleged to have been brought over from Ireland by Thomas Newby. They had a brass plug in the King's crown to make it appear golden when the coin was new.

[Red Riley 2]

Thanks everyone, this has been most helpful. I have checked out the Colin Cooke site and in the context of what is essentially a very scarce category of coins, it would appear that plugs only penetrating into, rather than through the piece are not that unusual.

But what a complicated way of making a low value coin...

[Sylvester 15]

That's right Scottishmoney they were made simply to keep Cornwall happy. Although the added benefit was that (in theory) a bimetallic coin would be harder to forge. However forgeries turned up, the tin turned out to corrode far too quickly and was clearly unsuitable for currency, worse still is the fact that tin and copper don't make good bedfellows and the presence of copper makes the tin corrode faster (or so i read but can anyone verify this as indeed the case?). Besides the point though it was a fairly unsuccessful and a fairly pointless exercise in British numismatics. Which makes me love them!

[scottishmoney 29]

By that measure the Newby coins were better in that they were brass and bronze, which are rather quite compatible unlike tin, which doesn't get along to well with any other metals accept perhaps lead.

[Sylvester 15]

Here is a catch 22 though. Tin coins with nice clean plugs tend to do better on the market than tin coins where the copper plug has fallen out or been removed. Applying that to high grade tin coins creates an interesting problem though. If you have an exceptionally high grade tin halfpenny (as per some of Colin Cooke's old examples) in EF with moderate tin lustre intact with the plug still in situ, but the plug shows verdigris or it is causing some slight corrosion to the tin around it, should the plug be left or removed?

Obviously this lands into the 'ethics' behind removing a copper plug and vandalising a coin, but what is better a high grade superb specimen (minus plug) of a lustrous tin coin or letting it corrode into a bog standard tin coin with plug like other eaten away coins?

A question i've often considered but never put to the floor.

[Red Riley 2]

From my recollection, the cause of this incompatability is called 'electrolytic corrosion' which is the same reason why a steel bolt into an aluminium component on your car (e.g. a brake cylinder) will be impossible to remove.

[scottishmoney 29]

I rather think that Sir Isaac Newtons 17th century brethren did not understand electrolytic corrosion, that came about later on, perhaps as a result of this miserable experiment in "cheap" coinage alternatives.

[Hussulo 6]

Here is a catch 22 though. Tin coins with nice clean plugs tend to do better on the market than tin coins where the copper plug has fallen out or been removed. Applying that to high grade tin coins creates an interesting problem though. If you have an exceptionally high grade tin halfpenny (as per some of Colin Cooke's old examples) in EF with moderate tin lustre intact with the plug still in situ, but the plug shows verdigris or it is causing some slight corrosion to the tin around it, should the plug be left or removed?

Obviously this lands into the 'ethics' behind removing a copper plug and vandalising a coin, but what is better a high grade superb specimen (minus plug) of a lustrous tin coin or letting it corrode into a bog standard tin coin with plug like other eaten away coins?

A question i've often considered but never put to the floor.

Good question. I reckon if it was safe to do so and I could remove the plug without damaging the coin or possibly the plug I would remove the plug, but keep it. That way if I ever came to sell or give the coin away it could be refitted (if possible) at the new owner’s request. It would have to be an exceptional coin and I would only remove the plug to save the coin. It would be a shame in years to come if there were no nice examples left for future generations to enjoy.

[Red Riley 2]

Good question. I reckon if it was safe to do so and I could remove the plug without damaging the coin or possibly the plug I would remove the plug, but keep it. That way if I ever came to sell or give the coin away it could be refitted (if possible) at the new owner’s request. It would have to be an exceptional coin and I would only remove the plug to save the coin. It would be a shame in years to come if there were no nice examples left for future generations to enjoy.

[Ch2toWm4 0]

Has anyone mentioned the problem of Tin Pest?

It is my understanding that tin 'comes' in two allotropic forms. At temperatures above about 13 degrees C (about 56 deg F), it is a stable metal. However, at cooler temperatures, it changes form. White blisters appear and grow).

Here is a web reference (http://en.wikipedia.org/wiki/Tin) to these 2 forms -

"Allotropes

Chemically tin shows properties intermediate between those of metals and non-metals, just as the semi-conductors silicon and germanium do. Tin has two allotropes at normal pressure and temperature, gray tin, and white tin.

Below 13.2 °C it exists as gray or alpha tin, which has a cubic crystal structure similar to silicon and germanium. Gray tin has no metallic properties at all, is a dull-gray powdery material, and has no known uses.

When warmed above 13.2 °C tin changes into white or beta tin, which is metallic and has a tetragonal structure. Converting gray tin power into white tin produces white tin powder. To convert powdery gray tin into solid white tin the temperature must be raised above the melting point of tin.

Gray tin can be a real problem, since metallic white tin will slowly convert to gray tin if it is held for a long time below 13.2 °C. The metallic surface of white tin becomes covered with a gray powder which is easily rubbed off. The gray patches slowly expand until all of the tin in the object is converted from the metal to the powder, at which point it totally loses its structural integrity and falls to pieces. This process is know as tin disease or tin pest. Tin pest was a particular problem in nothern Europe in the 18th century as organ pipes made of tin would sometime completly disintergrate during long cold winters. The transformation can be prevented by the the addition of antimony or bismuth.".

Bill

[Sylvester 15]

I had forgotten about that one! My tin farthing was grey.