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<p>[QUOTE=&quot;Conder101, post: 1557787, member: 66&quot;]The first thing you need to understand is where the colors in toning come from.&nbsp; Silver sulfide itself is actually black in color, so where do the colors come from?&nbsp; It comes from the light passing through the thin layer of silver sulfide, reflecting off the surface of the coin, and passing back through the layer again.&nbsp; The light waves as they pass through the layer interfere with each other strengthening some wavelengths and cancelling out others.&nbsp; What wavelengths get reinforced determines what color we see.&nbsp; And the thing that determines that color is how thick the layer is.&nbsp; It&#039;s called thin film interference. </p><p><br /></p><p>Now what determines how thick that layer is?&nbsp; Two major things are distance from the source of the toning, and contaminants on the surface.&nbsp; think of the bullseye toning you get from an album.&nbsp; The lighter colors are toward the center farther from the edge of the holes and closer to the edge you get the darker colors.&nbsp; Layers of oils, either from machines or skin oils results in slow growth of the silver sulfide layer.&nbsp; Clean areas grow the layer faster.&nbsp;&nbsp; On an uncirculated coin the surfaces tend to, but don&#039;t always, have roughly the same thickness layer of contaminants across the coin so toning is relatively even.&nbsp; But as the coin wears it collects skin oils&nbsp; and&nbsp; DIRT.&nbsp; All this stuff rapidly results in thick contaminated layers that do not show colors.</p><p><br /></p><p>Now over time that coin can still continue growing a silver sulfide layer getting thicker and thicker until you have a black tarnished coin, but you don&#039;t get color.&nbsp; But the wear the coin is not the reason you don&#039;t get color.&nbsp; If you take a worn coin and strip the surfaces back down to clean bare silver it may look dull and dead, but over time as the silver starts to react again it IS possible for colors to appear.&nbsp; The coin still won&#039;t look good, but it can have color.[/QUOTE]</p><p><br /></p>

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