1999-P obverse MD

[hasfam]

I usually don't mess with these but for some reason I thought this one looked interesting. Not sure why though.
Rock

[Dick]

Looks like to me, Die Deterioration Doubling, and maybe some MD. IMHO.
Dick

[eagames]

I agree, looks interesting but it's a teaser.

[hasfam]

That's a good word for it...teaser.

[Dick]

Ed, talking about a "teaser". did you see the "RPM", I posted in photo section? That could be a teaser, if not clarified.
Dick

[hasfam]

I see what you mean Dick. Those are close for sure. BTW, nice overlay job.

Rock

[Dick]

Thank you, Rock. That is my first overlay. I just wanted to see if it fooled anyone! It didn't. LOL
Dick

[hasfam]

Looks like to me, Die Deterioration Doubling, and maybe some MD. IMHO.

[Dick]

rock, I am no engineer, or even close, but I think, due to the size of the areas that are involved for the letters, and numbers, a stress factor, and repeated striking, will tend to weaken, and eventually cause "erosion" of the edges. IMHO.
Diock

[wavysteps2003]

O'kay all, "what is the cause of the doubling in 'die deterioration doubling'; what is the cause of the doubling on 'machine doubling?".

While both can be similar and both can happen on the same coin, they are formed differently. Look at the pictures again and explain how die deterioration doubling can form as it did on this coin?

BJ Neff

[Dick]

BJ, I believe my laso post explains, (more, or less) the DDD, while the Machine Doubling si a lateral shift in the metal. It can occur on any device. It is not the same as Ejection Doubling.
Dick

[hasfam]

Die deterioration is formed by wear or overpolishing.

Machine doubling is caused when the die is struck and "rattles" or "bounces".

I'm not exactly sure how die deterioration caused the doubling on this coin since it shows both on the inside and outside of the letters. Please explain.
Thanks
Rock

[hasfam]

I must also say that I am up to my eyeballs in wedding preparation for tomorrow and am not thinking as clearly about this as I should. Obviously I'm missing something here and would like to learn whatever it is that I am overlooking.

Thanks,
rock

[wavysteps2003]

Die deterioration doubling is caused mainly by metal flow over the face of the die. Each time a coin is struck, metal from the center of the planchet flows outward towards the rim. This phenomena is called "cold metal flow".

As the metal flows, it strips away the atomic layers of metal on the die surface. If this flow was evenly done, there would be no die deterioration doubling, however, it is not. Since there are both raised and incused designs on the die face, the metal flow is not even throughout the surface. This sets up high and low pressure points. The high pressure points restricts the flow of metal, thus not stripping away as many atoms from the face as an area of low pressure where more atoms will be stripped away.

A low pressure point has less restrictive force on metal movement, so it allows more atoms to be stripped away from the die surface because more metal moves across that area.

Now, lets us look at two examples that we all can equate to. The rippling of a stream bed or the rippling of the sand as a wavy retreats. In both cases, sand is removed, not in an even pattern, but in a pattern dictated by the high and low pressure points formed by the movement of water over the sand. The high points of the ripples are the high pressure areas and have slower volume of water flowing over that point than the recessed area or the low pressure area. Of course, both the sandy bottoms, especially the beach sand are in a constant stage of flux and the patterns do change continuously. However, this is not true of the die surface.

When areas of high pressure and low pressure are formed, they remain consistent throughout the dies life only changing slightly due to metal flow.

Let us look at the 1955 "poor man's double die" and analyze what happened to create the extra portion of the 5 digit that is often seen.

In the beginning of the dies life the recessed area in the die which represents the five digit is a low pressure point. The point in the field immediately following that recess is a high pressure point, an area that metal flow is restricted. This high pressure area has been caused by the die face and the planchet meeting flush. Just after that, an area of different pressure will result, which will result in an increase of metal flow over the surface of die. This slight increase of metal flow will strip away more atoms in that area than in the high pressure area. As more and more atoms are stripped away in that area, the pressure decreases and the flow of metal increases. After a period of time, enough atoms are removed in that area of the die that a indent or recess is formed on the die face, which equates to a raised area on the coin or "doubling"

While mostly all die deterioration doubling forms away from the center of the coin or towards the rim, you can also have die abrasion doubling which is basically the same thing since it is formed by the same action. With die abrasion doubling, the doubling will be in the direction of the abrasion force.

Lastly, die deterioration doubling and die abrasion doubling can form split serifs giving it the appearance of a true doubled die.

So, in the above case, this is machine doubling. It was caused by a loose die and the coin hitting the retreating die which flattened out a portion of the design element.

BJ Neff.

[eagames]

I would say if doubling is from die polishing that would be abrasion doubling.

Deterioration is from metal flow, it often moves to the rim or in all directions around the design. As BJ described.... it reminds me of a beach or the edge of a canyon with a pattern of lines or ripples but those are caused by water/wind and the die deterioration is from metal flowing as it moves over the die over it's use.

MD is from chatter while the coin is struck.

This coin looks like deterioration since it goes in more than one direction but on this coin it might have also been helped by MD as well.