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<p>[QUOTE=&quot;GDJMSP, post: 659774, member: 112&quot;]Lehigh - some food for thought.</p><p>&nbsp;</p><p>I have always believed in the the theory that certain areas of a coin are more prone to toning, those areas tone faster and more easily in other words, because of the flow lines in the metal in those areas - in particular the fields - as opposed to the flow lines in the devices and legends. I suppose it&#039;s similar in a way to what you are saying, but said in a different way. But there is one major difference. Now I don&#039;t have the degrees you do, to me it&#039;s just common sense.</p><p>&nbsp;</p><p>I have explained this idea many times, but given all the new members perhaps it should be explained again. The same idea, or theory, also explains why different coin types tone so differently.</p><p><br /></p><p>First you have to realize that the thing that makes coins tone is the exposure of the metal&#039;s surface to the air and the toning catalysts that the air contains. It can also be affected by surface contact of the metal with other materials like cardboard, paper, wood etc.</p><p>&nbsp;</p><p>I wish I could get the size of these to be different so that I could illustrate what I mean, but I can&#039;t so you&#039;ll have to just imagine what I try to explain.</p><p><br /></p><p>Think of the surface of the fields on a Morgan dollar as looking like this - /\/\/\/\/\/\ - this is to show what the flow lines in the metal look like if greatly magnified. These lines are created of course because the coin planchet is subjected to great pressures when the coin is struck and that pressure cause the metal to move, flow, almost as if it were liquid. But it isn&#039;t liquid, so when the top portion of the metal flows it creates tracks (flow lines) in the underlying portion of the metal.</p><p><br /></p><p>Now what you are talking about is that the metal in the areas of the devices and legends becomes harder, more dense, more compressed, if I understand you correctly, as it is forced into the depressions of the die during striking. </p><p><br /></p><p>But this seems counterintuitive to me. The portion of the metal that undergoes the greatest pressure is in the fields. Remember, the planchet is flat before it is struck. And it is part of this flat metal that is being forced up into the recesses of the die. And just like when you step into soft mud while barefoot and the mud squishes up between your toes, the part of the mud that is compressed the most is the part under your foot, while the mud that comes up between your toes is looser, softer and less dense than the mud under your foot - so is the metal that is squeezed into the recesses of the die less dense and softer than the metal in the field areas.</p><p><br /></p><p>This causes the metal squeezed into the devices to have a completely different and smoother surface texture (flow lines) than the metal in the fields has which looks like this - /\/\/\/\/\/\</p><p><br /></p><p>Now it is commonly explained that the reason that products like Nic-A-Date work to make dates and details that have been worn down smooth is because the underlying areas of the date and details is more dense than the surrounding area or fields. This when the acid is placed on the metal it eats away the adjoing field area and leaves the date &amp; details visible once again. Now this is true, the areas directly under the dates and details are harder because that is precise spot that was subjected to the greatest pressure during striking. However, what it fails to explain is that the top portion that was worn away was softer than those underlying areas that are on the same plane as the adjoining fields.</p><p><br /></p><p>So the work hardened area that you refer to is actually where the device or letters in the legend meet the fields - not at the top of the device or letters. And this work hardened area actually has the same type of flow lines that the fields do, they are even somewhat exaggerated at times, larger, deeper flow lines than those found immeadiately outside their edges. While the surface of the device or legend ends up being smoother than the adjoining fields.</p><p><br /></p><p>Now with Morgans, because the devices &amp; legends are intentionally all frosted due to die preparation, these surfaces (flow lines) are even more different still than the surface of the fields. But with other coins, where the devices and legends were not frosted as on Morgans, it is readily seen that their surface is much smoother, flatter than the fields. Again, this is because these areas are not subjected to as much pressure as the fields and thus do not develop the flow lines that the fields do.</p><p><br /></p><p>Now all of this brings us back to my little illustration of this - /\/\/\/\/\/\. Now rather obviously such a surface, as found in the fields, exposes a great deal more area to the air than a smoother, flatter surface that looks like this - ________&nbsp; (yes I know the tops of the devices and legends are not completely flat, but I cannot illustrate a curved surface with the keyboard) - as found in the devices, would expose to the air. Thus the fields tone much more readily, easier, than the tops of the devices and legends do. </p><p><br /></p><p>This is why toning occurs the way it does. Not because the tops of the devices and legends are work hardened, they aren&#039;t. They are actually softer than the surrounding metal of the fields.</p><p><br /></p><p>Hopefully this all makes sense.[/QUOTE]</p><p><br /></p>

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