Can Proof-like Coins still have Cartwheel Luster?

So basically one is saying that luster is created by 'shallow' grooves (may be off on what the term actually is on a fresh die) and as the die is used and the planchets are struck, the face of the die wears down, which still gives luster up until the point that the grooves are not shallow enough to reflect light properly for luster. It still will from then on create the other type, so to speak, of luster, which isn't properly luster because it is being created from too deep of grooves to reflect the proper light. People just call it luster because they are recognizing it as shiny and reflective, but more properly it is not luster because that has been destroyed in the minting by flow lines on the die being too deep or wrongly angled, or such. And of course, since luster is such a ephemeral type of quality, easily destroyed just be rubbing down the small amount of proper depth grooves that create it, it is necessary to be able to properly spot it.

Is this correct?????

 

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Luster is a word like "automobile", it can refer to anything from a SmartCar to a Maybach.

 

As we get in elementary Chemistry classes, metals have certain characteristics, including ductility and malleability. The ability to be drawn into wires and the ability to be deformed by stress into sheets (or coins or auto fenders if they are in the correct die). Doesn't have to be liquid.

 

Kentucky, wouldn't it be more correct to say that, during the strike, metal behaves in ways more usually expected from a liquid than a solid? That's how I've always visualized it.

 

Good food for thought, but does an auto fender flow?

 

To my mind, any dimensional alteration in the position of individual molecules for mechanical reasons should qualify as "flow." To split hairs, the speed with which it happens also factors.

 

Does glass flow?

 

No more or less than a coin does. The process, as applied to coins, is known as "cold flow," and is quite different from liquid flow.

No. This is a common myth, but Corning breaks it down here: http://www.cmog.org/article/does-glass-flow

 

What colloquial (teachable) verb is appropriate for the physical behavior of metal during a strike? The symptoms, to me, are similar.

 

The word creep occurs to me.

 

Creep is certainly analagous to the "flow" of glass. However, creep is defined as deformation under a low load for an extended period of time. A coining chamber has neither low load, nor a long time.

The correct term, in materials sciences, is cold flow. It is related to the ductility of a material. After the applied stress exceeds the yield stress, there is permanent deformation of the material, and it conforms to the die.

 

Thanks, guys. I'm entirely self-taught, and there are some surprising gaps in my knowledge as a result. This was one of them.

 

Thanks to physics-fan3.14 explanations + Kentucky, Paul M., BadThad, SuperDave and Doug, it looks like no one who reads the LAST FEW PAGES (#3 on) of this thread on CT should have any misconceptions about what luster is, what coin luster refers to, how coin luster is produced, the types of coin luster, planchet flow during the strike, die erosion, etc.

This has been explained to be true.

Now, if a poster has the time to condense all the corrected info in this thread, I believe it should be posted in the "important info section" for newbies. I shall try this week.

 

To use Reductum ad absurdum, a totally worn out die should have luster to die for.

 

Uh..........................was that for me!!!!!!!!!!!!!!!!!!!!

 

C'mon, man. Your post worked on half a dozen levels at once. How could he not?