Degree of double strike

[myt]

Hi, 

I was just wondering about thoughts on how common various degrees of double striking would be, like if someone was aware of some standard where a coin would have been rejected for distribution by the mint. I came across this James 1 shilling which is so double struck, the "M" in "MAG" looks like two "As" (among other things like two left shoulders and a distorted shield).  

 

Thanks for any thoughts!

[Rob]

Quite common across all flan sizes. The number of double struck coins implies that they did not reject them for this reason. The only important criteria was the weight, as each silver coin was supposed to have it's value equal to the silver content.

It may or may not detract. A screwed up portrait such that you can't make out the features or an illegible legend will count against it.

[myt]

Thanks Rob - slight slip-up in my last post was not "MAG" but "ANG", hence why two A's in the obverse legend "AANG"

[Rob]

It's rotated between strikes. The A is seen twice, but the other doubled letters have been erased. You can tell there is a displacement from the state of the inner circle.

[blakeyboy]

I find rotational analysis such as this fascinating- 'forensic numismatics'...

I don't know enough about coin striking to probably be correct on this, but if a coin is in a collar when struck it can only rotate 

about it's centre( ? ), unless something goes strangely wrong, but with hammered, is it true that a coin can therefore rotate about any point,

even about a point that is outside it's own circumference?

Or move with no rotational element at all - just a sideways move?

Did it always take more than one hammer blow?

[Rob]

We had this discussion a while ago. Dave Greenhalgh was here saying you only had one blow with the hammer, which is unquestionably true for small coins (he does this all the time). The hammer can bounce leading to double striking, but I think the question of more than one blow could apply to larger modules. I used my type 5 halfcrown as an example, see below.

There is unquestionable double striking by the horse's rump and by the S on the obverse, and the N & H on the reverse. The relief of the obverse has a significant change of angle which is obvious with the lighting, and a similar profile change in the diametrically opposed part of the flan. I couldn't see how a bounced strike could produce such a large change of angle whilst still producing what is quite a well struck up coin.

Looking to pick holes in my thoughts, the only way you could get this profile with a double change of angle would be if the die was cut with the angles as seen, which isn't impossible. Although it is counter-intuitive to presume the die was engraved on a deliberately non-planar surface, I suppose an angled profile such as this would constrain movement along the 1 o'clock/7 o'clock axis, but the lower and less angled profile on the 10 o'clock/4 o'clock axis would allow some lateral movement. The double striking seen on this coin would agree with the above, so maybe I'm wrong in thinking it was struck more than once. Don't have a ouija board to find out. 

Edited January 18, 2021 by Rob

[Paulus]

Here's my 'double-struck' shilling as an extreme example

[myt]

2 hours ago, blakeyboy said:

I find rotational analysis such as this fascinating- 'forensic numismatics'...

I agree... when minting has become increasingly/entirely mechanical, it seems that people strive to find 'microscopic' double striking in some cases which may or may not considerably increase the value of the coin. With hammered coinage, this massive kind of double striking is cool in that it actually is completely altering the coins appearance (e.g. "AANG", two tails on a horse, and a unique crown/incomplete for Charles). I feel like it adds some artistic appeal, and gives some insight into the day of the person minting - did they notice? (possibly) Did they not care? (probably). Was it the last coin of the day? (we will never know)

[secret santa]

Can someone explain how the border legend has been double struck but the central design has not ? The obverse is the same.

[Rob]

I think it has been double struck. There are a couple of anomalies to the centre such as the line on the shield to the right of the trident shaft which is rotated approximately correctly for the legend displacement, and the left trident prong is mangled. The lettering is better formed on the right R of the pair and you can see a colon underneath the terminal A. In fact, all the left letters appear marginally thinner than those on the right, which would be right if they were the first strike, subsequently reduced by metal inflow from the second strike. Same applies to the date where it is the right digit of the pair which is thinner.

[blakeyboy]

Is a definitive fact that the obverse and reverse dies were single pieces of metal, and not concentric, so the outside could rotate like in the picture leaving the centre basically struck as usual?

[Rob]

3 hours ago, blakeyboy said:

Is a definitive fact that the obverse and reverse dies were single pieces of metal, and not concentric, so the outside could rotate like in the picture leaving the centre basically struck as usual?

Yes.

If concentric then you would have the legend all over the place without restraint, even if it wasn't double struck. The complexity of locking two rings in position for each side and furthermore locating and locking them in the press so that the die axis is maintained is mind boggling. Don't forget you also need a collar, together with a mechanism for introducing the blank and expelling the struck coin.

Not a penny, but the same principle applies.

https://www.coinbooks.org/esylum_v18n51a24.html

[mrbadexample]

On 1/18/2021 at 3:14 PM, secret santa said:

Can someone explain how the border legend has been double struck but the central design has not ? The obverse is the same.

Super coin. What's the obverse like please Richard? 

[mrbadexample]

Forget that, I found it.

[TomGoodheart]

I quite like this one with the serpentine double O on the reverse.  Fortunately the main parts of the design are pretty much unaffected.  So I can live with the quirkiness.  🙂