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<p>[QUOTE=&quot;Rob Woodside, post: 7497769, member: 96187&quot;]Thanks Jeff. That&#039;s my position too. </p><p><br /></p><p>So your position is that flow lines are like the scratches left on granite by long gone glaciers. When I began writing today mine was that die wear was a red herring and true flow lines were ripple marks, not scratches, and required no debris or foreign matter to form. Now I&#039;m not so sure. How do you explain both chatoyant and non chatoyant MS coins of the same issue? Higher die pressure for some? Longer strike time for some? (Since coins have been milled they are pressed and not &quot;struck&quot;.) Clean dies is the simplest explanation but how to test it?</p><p><br /></p><p>Your scratch theory suggests tests for the debris. Can debris size be correlated to scratch size? In glacial scratches you get the direction of motion from the abrupt end to the groove when the debris finally disintegrated. Can anything similar be seen on a coin? A possible weakness here is that the glaciers came by only once and we are looking at surfaces produced by dies used many times but only once on any commercial strike. It is not clear to me how the debris would wear the die. Each new planchet brings a little new debris adding to what has already accumulated on the die. Would the debris wear scratches in the die that would make ridges on the coin rather than grooves?[/QUOTE]</p><p><br /></p>

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