World of Coins

Research and reference => Coin and medal production technology => Topic started by: <k> on October 02, 2015, 01:29:50 AM

Title: Ghosting
Post by: <k> on October 02, 2015, 01:29:50 AM
(http://www.worldofcoins.eu/forum/index.php?action=dlattach;topic=13579.0;attach=57030;image)

Mauritius, 200 rupees, 1971.  Independence commemorative.

The reverse design illustrates the novel Paul et Virginie (https://en.wikipedia.org/wiki/Paul_et_Virginie) by the French author Jacques-Henri Bernardin de Saint-Pierre (https://en.wikipedia.org/wiki/Jacques-Henri_Bernardin_de_Saint-Pierre).

 
Title: Re: Ghosting
Post by: constanius on October 02, 2015, 07:05:12 PM
In the obverse field it seems as if you can make out some of the reverse design.

Pat
Title: Re: Ghosting
Post by: <k> on October 02, 2015, 07:13:33 PM
Can't see it, myself. Do you see ghosts in real life?  ;)
Title: Re: Ghosting
Post by: constanius on October 02, 2015, 07:32:44 PM
You cannot see anything in what should be the plain field on the obverse?

As if the metal has been drawn into the reverse design, "I.M.D.P" -( Internal Metal Displacement Phenomenon )

I have seen ghost imaging on coins, not ghosts. :)

 http://www.worldofcoins.eu/forum/index.php?topic=8334.0    (http://www.worldofcoins.eu/forum/index.php?topic=8334.0)


(http://i300.photobucket.com/albums/nn21/constanius/Mauritius%20200%20rupees%201971a.jpg)

Pat
Title: Re: Ghosting
Post by: constanius on October 02, 2015, 10:34:41 PM
(http://i300.photobucket.com/albums/nn21/constanius/Mauritius%20200%20rupees%201971a-horz.jpg)

Horizontally flipped reverse & layered at 20% over obverse.

Pat
Title: Re: Ghosting
Post by: constanius on October 05, 2015, 09:24:00 PM
Noticed you are using a different image in the original topic before this "split" does that mean that you can now see the "ghosting", as you have made no comment. 

This comparison shows the difference in jaw line on QEII caused by, most probably, "I.M.D.P" the only other causes that I can think of would be actual die distortion, underweight planchet(there being not enough metal for a good strike), die clash, or, less likely, adjustment of the die strike being wrongly set.

(http://i300.photobucket.com/albums/nn21/constanius/Good%20Example-horz.jpg)

Whatever the cause this is a very rare phenomenon and I admit that I was expecting a reply as the purpose of these forums is to share & expand our knowledge. 

Pat
Title: Re: Ghosting
Post by: <k> on October 05, 2015, 10:30:55 PM
Noticed you are using a different image in the original topic before this "split" does that mean that you can now see the "ghosting", as you have made no comment. 

I split the topic for two reasons: I felt that the "ghosting" issue was detracting from the purpose of my design topic; however, I recognised that the ghosting really deserved a topic of its own. I made no comment, since physical aspects such as this do not interest me and I have no intuitive understanding of them, therefore I had nothing to add, though I expected others would. Over to the members, now!  :)
Title: Re: Ghosting
Post by: FosseWay on October 06, 2015, 09:56:49 PM
I learnt about ghosting in connection with George V coppers from the UK. The first series (1911-26), especially the penny, show precisely the phenomenon Constanius points out above. The various changes to the portrait in the mid- to late 1920s were intended to deal with the problem.

On the Mauritius coin at the start of this topic, is it just me or is there something distinctly odd about the kerning of the text on the obverse? The letters of QUEEN are to my eyes at least much closer together than those of SECOND, while the date is even more widely spaced. I can kind of accept that the date might be deliberately different but the lack of uniformity across the rest of the inscription makes the coin look unbalanced.
Title: Re: Ghosting
Post by: <k> on October 07, 2015, 12:27:05 AM
The letters of QUEEN are to my eyes at least much closer together than those of SECOND, while the date is even more widely spaced.

I agree with your perception, though it's not something I would have noticed without being prompted. The E and L in ELIZABETH are even closer together. Christopher Ironside would have modelled the lettering by hand, back in those days.
Title: Re: Ghosting
Post by: mrbadexample on April 18, 2016, 01:56:38 PM
I learnt about ghosting in connection with George V coppers from the UK. The first series (1911-26), especially the penny, show precisely the phenomenon Constanius points out above. The various changes to the portrait in the mid- to late 1920s were intended to deal with the problem.

Example of such: