1806 Penny defect

[German 0]

Very specific gouges are present on this coin close to the rim - this can be found on a lot of coins from this period. How would you explain this? obviously it's a defect, but what kind and how did it come to be?

thank you

[Rob 3,152]

I think it might be due to a build-up of tiny metal particles produced by striking or present on the blanks due to being insufficiently cleaned. Each time a coin is struck it is virtually guaranteed that a small amount of metal dust will be produced simply from the act of rubbing two metal surfaces together. Given that there is a collar giving further confinement, unless there is an efficient jet of air to blow away the rubbish the only way to dispose of this residue would be to incorporate it into the next coin, to block the dies or bond it to the flat die surfaces. As it is usually found in conjunction with evidence of blocked dies, I suspect it is excess rubbish building up and bonding to the dies. On a microscopic level even a polished die surface is full of humps, troughs and sharp edges which would provide a foothold for foreign objects to bind. Mechanical slack in the machinery would help to distribute it. Just a theory, but it sounds logical given that these marks always seem to be associated with the outer parts of blocked legend and rarely elsewhere.

[German 0]

have you actually encountered something like this, and if so do you know the name of this process? or are we talking pure theory here?

[Rob 3,152]

have you actually encountered something like this, and if so do you know the name of this process? or are we talking pure theory here?

No, we are talking theory for the depressions, but the weak lettering from die fill is already established as is a cud mistrike where you incorporate a small amount of metal into the flan. If you look at where these depressions occur you will find they are always associated with weak or blocked letters. Granted a depression in the flan is bound to result in a weak letter, but to create the depressed marks either the flan is defective prior to striking with incuse flaws or the die has raised lumps. As they nearly always appear to follow the curve of the legend I think they are on the die as they tend to follow a line along the radius suggesting they are formed by mechanical rotation. The only way I can envisage raised areas appearing on the die is by trapped and incorporated solid material. To be on a prepared blank in such a consistent position and to such a significant depth suggests to me this is not the likely option. In striking a coin, the effects of any rotational mechanical slack would be accentuated the greater the distance from the centre of rotation because the arc length is greater. A greater distance moved would result in more metal dust formed, so you would expect to see more evidence near the rims.

Edited January 31, 2007 by Rob

[German 0]

thanks a lot, Rob!

[Teg 0]

Hi,

Being ignorant about a topic has never stopped me in the past so why should it now!

Do these gouges always occur in matched obv. / rev. pairs like this coin? If so metal build up seems less likely. A characteristic of metal build up and metal cuds in letters is that they fall off at some time – and leave an impression on another coin. Does this happen?

Not that I have a much better solution.

Cooper “The Art and Craft of COINMAKINGâ€

“The automatic coining presses with their accurately machined collars and die necks required a correctly sized blank. ….. the technique of striking in a collar was different from that of striking without one. In the latter case the metal had been allowed to flow radially outwards in an unconstrained manner which had resulted in better struck coin centres, but a collar constrained the flow of metal between the dies. It was found that by rimming, thickening or rolling the edge of the blank to give it an accurate diameter, a better coin could be struck, particularly at the edges. There can be little doubt that Boulton rimmed his heavy copper blanks with their thick edges to produce the 1797 penny and twopenny pieces, otherwise he would have had difficulty in striking the excellent edges of these coins.â€

Has this penny been struck from a non or lightly rimmed blank? Is it therefore a metal flow problem?

Teg

[Rob 3,152]

Hi,

Being ignorant about a topic has never stopped me in the past so why should it now!

Do these gouges always occur in matched obv. / rev. pairs like this coin? If so metal build up seems less likely. A characteristic of metal build up and metal cuds in letters is that they fall off at some time – and leave an impression on another coin. Does this happen?

Not that I have a much better solution.

Cooper “The Art and Craft of COINMAKINGâ€

“The automatic coining presses with their accurately machined collars and die necks required a correctly sized blank. ….. the technique of striking in a collar was different from that of striking without one. In the latter case the metal had been allowed to flow radially outwards in an unconstrained manner which had resulted in better struck coin centres, but a collar constrained the flow of metal between the dies. It was found that by rimming, thickening or rolling the edge of the blank to give it an accurate diameter, a better coin could be struck, particularly at the edges. There can be little doubt that Boulton rimmed his heavy copper blanks with their thick edges to produce the 1797 penny and twopenny pieces, otherwise he would have had difficulty in striking the excellent edges of these coins.â€

Has this penny been struck from a non or lightly rimmed blank? Is it therefore a metal flow problem?

Teg

I'm open to persuasion given the right side of the obverse matching with the reverse, although the large depression on the left obverse has no corresponding weakness on the reverse assuming the die axis is properly inverted.

For what it is worth, my 8 Soho halfpennies with this feature are as follows. 3 have a depression on one side only (all reverses), 3 on both sides but not matching and 2 matching. On none of them is there any notable degradation of the edge or rim including the recessed security edge detail which I would possibly expect if it is a flow problem. All are in top grade with wear and mishandling eliminated although none of them are particularly badly affected which may be significant. Of these 8, 3 are 1799 and 5 are 1806, so I assume that the problem being known about long before the time the 1806's were struck would have resulted in better quality control of the blanks.

Thinking along the lines of metal flow, how about slightly undersized flans? It's a pity these are Soho products. If they had been Royal Mint products it would have been possible to examine the dies.

[Teg 0]

Hi,

Being ignorant about a topic has never stopped me in the past so why should it now!

Do these gouges always occur in matched obv. / rev. pairs like this coin? If so metal build up seems less likely. A characteristic of metal build up and metal cuds in letters is that they fall off at some time – and leave an impression on another coin. Does this happen?

Not that I have a much better solution.

Cooper “The Art and Craft of COINMAKINGâ€

“The automatic coining presses with their accurately machined collars and die necks required a correctly sized blank. ….. the technique of striking in a collar was different from that of striking without one. In the latter case the metal had been allowed to flow radially outwards in an unconstrained manner which had resulted in better struck coin centres, but a collar constrained the flow of metal between the dies. It was found that by rimming, thickening or rolling the edge of the blank to give it an accurate diameter, a better coin could be struck, particularly at the edges. There can be little doubt that Boulton rimmed his heavy copper blanks with their thick edges to produce the 1797 penny and twopenny pieces, otherwise he would have had difficulty in striking the excellent edges of these coins.â€

Has this penny been struck from a non or lightly rimmed blank? Is it therefore a metal flow problem?

Teg

I'm open to persuasion given the right side of the obverse matching with the reverse, although the large depression on the left obverse has no corresponding weakness on the reverse assuming the die axis is properly inverted.

For what it is worth, my 8 Soho halfpennies with this feature are as follows. 3 have a depression on one side only (all reverses), 3 on both sides but not matching and 2 matching. On none of them is there any notable degradation of the edge or rim including the recessed security edge detail which I would possibly expect if it is a flow problem. All are in top grade with wear and mishandling eliminated although none of them are particularly badly affected which may be significant. Of these 8, 3 are 1799 and 5 are 1806, so I assume that the problem being known about long before the time the 1806's were struck would have resulted in better quality control of the blanks.

Thinking along the lines of metal flow, how about slightly undersized flans? It's a pity these are Soho products. If they had been Royal Mint products it would have been possible to examine the dies.

Hmm,

Peck makes the point that when the currency dies were used for restrikes the weak or blurred legends do not appear. That led him to the conclusion that it was the mass production - rather than the dies that were to blame.

What would happen to a few drops of oil on the blank (within the raised rims) if the die / blank made a perfect seal when striking?

Are your 1/2d examples all average weight?

Teg

[Rob 3,152]

Hmm,

Peck makes the point that when the currency dies were used for restrikes the weak or blurred legends do not appear. That led him to the conclusion that it was the mass production - rather than the dies that were to blame.

What would happen to a few drops of oil on the blank (within the raised rims) if the die / blank made a perfect seal when striking?

Are your 1/2d examples all average weight?

Teg

On the first point about Taylor restrikes it is almost certain that visually good dies would be used or polished to remove any obvious defects and the quantities struck are minimal relative to the mass produced pieces for currency. They would also be inspected individually whereas the currency pieces would not be. Also the proofs KH42 and KH43 struck at Soho from current dies would not be struck from defective ones. I think that's probably a red herring.

I believe you get a generally flat relief over a wide area as the oil/grease spreads out quickly, but doesn't compress and so protects the flan to some degree from making a sharp impression.

My 1806s are all about the official weight. The 1799s are within the range quoted by Peck, but the largest defect is on the heaviest piece at about 200 grains.

I would feel a bit happier with the metal flow argument if there were signs of metal flowing in the adjacent legend just as you get on pieces struck without a collar, but there are none. In fact, the surface of the large defect on the obverse above looks a bit grainy which would definitely be incompatible with metal flow, but would be appropriate for a flan flaw or something on the die.

[Teg 0]

I have not given this a lot of thought -as it hardly effects farthings.

Often I find that looking at contemporary counterfeits gives a good idea about what happens with low weight blanks / poor striking. The few counterfeits of Boulton's coinage I have seen all looked good.

I have attached a late 18th century ctft 1/2d. This is thought to show metal loss due to, "not enough metal to fill the die".

Bit of another red herring, as it is obviously not struck in a collar.

Any thoughts?

Teg

[Rob 3,152]

I have not given this a lot of thought -as it hardly effects farthings.

Often I find that looking at contemporary counterfeits gives a good idea about what happens with low weight blanks / poor striking. The few counterfeits of Boulton's coinage I have seen all looked good.

I have attached a late 18th century ctft 1/2d. This is thought to show metal loss due to, "not enough metal to fill the die".

Bit of another red herring, as it is obviously not struck in a collar.

Any thoughts?

Teg

Not sure about the argument there not being enough metal to fill the die. If it's struck without a collar and on a fly press the quality of impression will depend on the profile of the flan and die and crucially how much force is used. A perfect strike will give a thinner flan than found normally if an underweight blank is used, but the depth of strike will depend on the force applied. If the flan isn't of a consistent thickness, then you would expect an uneven strike compared to a flat blank unless sufficient force were used to overcome the variation. If a consistent force applied by the fly press was used in their manufacture, then you would expect a poor strike should be due to a poor quality blank such as being too hard, uneven or even too soft such that the metal flows too easily and spreads to a greater diameter.

Edited January 31, 2007 by Rob