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<p>[QUOTE=&quot;Kasia, post: 1757425, member: 31533&quot;]mechanical doubling is the same as strike doubling and is attributable to the process during the coining of the coin, as opposed to a result of what the die is actually coining onto the planchet. MD is a result of bounce or vibration introduced into the process whereby the die as it strikes the coin is either in a vibration or &#039;bounces&#039; (skims) the coin, so that it essentially is kind of doing a double strike to some extent, although it is done in one strike. Think of it this way. If you are hitting something to put an impression in it, and instead of going down smoothly and hitting it once clearly, it has a slight tremor and it give it not a clear impression. That is a way to describe MD. Sometimes you can see esentially the same thing when you do a stamp (like for a return address or something) and you are somewhat in motion at the time you make the &#039;strike&#039;.... it can leave parts of the impression off or doubled, like in MD.&nbsp; Now die deterioration is more like a variety, in that the strike is not neccessarily bouncing or off, but the actual metal on the die has become unstable or flow lines have been created on the field area (usually) and around some of the sharper deliniated letters or parts of the design. It may be striking the coin without any real vibration or bounce, but it creates an effect that shows &#039;doubling&#039; that is not a doubled die. Because of the wear neccessary to cause this kind of flow and deterioration, there is no set pattern that it can take, and it may show up, based on the use of the die either as portions of the die (as in parts of the die have either been fatigued in the metal at that point or has been excessively used due to positioning in the striking holder/chamber and other considerations). Sometimes you see die deterioration with mostly flow lines and little distortion on the lettering, other times it is only on parts of the design or lettering as distortion. Metals are &#039;fluid&#039; in a sense in that even steel is not a single unit. Fatigue can apply to only portions of the steel in a die. But MD is more a glancing type of phenomenon, and die deterioration is more of a distortion of the features. Kind of hard to explain, but essentially, MD is an &#039;error&#039; and Die deterioration is a &#039;variety&#039;. Even though MD can look exactly the same on a number of coins, it is really not a variety, because the &#039;doubling&#039; doesn&#039;t exist on the die, but is impressed on the coin due to the striking vibration and/or bounce, and the reason it looks the same is because of the way the die is positioned that the tolerance level for looking alike is introduced. But die deterioration is, essentially a variety, as each coin struck at that moment from the same die will be the same, with the exception of how the deterioration progresses (either quickly with a catastrophic failure) or slowly with introducing more fatigue symptoms into the actual die.[/QUOTE]</p><p><br /></p>

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