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<p>[QUOTE=&quot;RonSanderson, post: 3281379, member: 77413&quot;]I really like the theory of work hardening.</p><p><br /></p><p>Let&#039;s take another look at my 84-P Jefferson.</p><p><br /></p><p>[ATTACH=full]867464[/ATTACH]</p><p><br /></p><p>I use 9 photos to make my animations. Of those 9, this lighting angle shows off the haloing around the devices most strongly. The two arrows show the boundaries of areas of haloing that wrap the letters WE and appear at the edge of the nose and lips.</p><p><br /></p><p>The photo above showed that these areas both have mirror-like reflectivity. And there is minimal toning - you can see only the faintest hint of orange above and to the left of the rightmost arrow.</p><p><br /></p><p>As I learned on this forum, the metal has to flow inwards from the rim to fill up the large depression in the die that becomes Jefferson&#039;s bust. Metal also has to flow up into the letters. This latter flow happens in close quarters - within the W the metal has to flow into multiple close branches of the letter.</p><p><br /></p><p>It just makes sense to me that higher stresses are suffered by the metal where these boundaries occur. That effect should be reflected both in the planchet simply due to metal flow, but it also stresses the die and deforms its surface too.</p><p><br /></p><p>Further, we should go back a step and consider die reproduction. The process of stamping a pattern into the die also affects both the positive and negative dies and they also have high stresses where the metal must flow most radically. So we may also find these patterns becoming engrained in the dies and masters.</p><p><br /></p><p>As to specifics, we have a halo around the letter edges that<i> could</i> be due to increased metal flow up into the devices. That would cause a different surface structure - perhaps a precursor to what we see as die erosion. In the fields, the flow is more of a straight compression, since the planchet is being made thinner here but is fairly distant from the more lateral flows that fill the devices.</p><p><br /></p><p>This is all speculation, so let me know if it&#039;s hogwash. (And why, preferably!)[/QUOTE]</p><p><br /></p>

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