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<p>[QUOTE="TypeCoin971793, post: 3336686, member: 78244"]More pictures!</p><p><br /></p><p>Here is a proof Principality of Sealand half dollar. This picture was taken over the frosted parts of the devices. I see very granular surfaces which are consistent with a sand-blast or acid-etc treatment on the dies prior to striking.</p><p><br /></p><p>[ATTACH=full]883864[/ATTACH]</p><p><br /></p><p>Here is a picture from the mirror field. The diagonal lines are latent die polish marks since almost all of the lines I saw were in the same direction and went clearly under the devices. The specks may be dust, impurities in the metal, or imperfections in the die.</p><p><br /></p><p> [ATTACH=full]883866[/ATTACH]</p><p><br /></p><p>This was the most interesting image of the three. The polish lines are still going in the same diagonal direction. But lookie here! There are some lines which are perpendicular. I only found these near the edge of the coin, which makes me believe they are early metal flow etch lines. They all have a consistent shape: a head pointed toward the center of the coin with a tail that gradually gets thinner. Logic and a very limited knowledge of metallurgy suggests that as the metal accelerates during striking, the metal etches deeper into the die. If that is the case, then this is clear evidence that metal flows from the rims inward, as [USER=112]@GDJMSP[/USER] says happens.</p><p><br /></p><p> [ATTACH=full]883867[/ATTACH]</p><p><br /></p><p>Now this coin is a Perth Mint 1 oz Star Trek silver round. The interesting thing about this coin is that it is a reverse proof. The following picture was taken in the field, which shows the granularity seen on the devices of the Sealand half dollar above.</p><p><br /></p><p> [ATTACH=full]883868[/ATTACH]</p><p><br /></p><p>When I placed my microscope over the brilliant devices, however, I saw a very cool image. With no flow lines or die polish to distract the camera, you can see the crystalline pattern of the metal.</p><p><br /></p><p> [ATTACH=full]883869[/ATTACH]</p><p><br /></p><p>While taking the pictures, I accidentally touched the surface of the brilliant area. To my horror, I saw that I had really messed up the surface. This goes to show just how delicate proof surfaces are.</p><p><br /></p><p> [ATTACH=full]883870[/ATTACH][/QUOTE]</p><p><br /></p>
[QUOTE="TypeCoin971793, post: 3336686, member: 78244"]More pictures! Here is a proof Principality of Sealand half dollar. This picture was taken over the frosted parts of the devices. I see very granular surfaces which are consistent with a sand-blast or acid-etc treatment on the dies prior to striking. [ATTACH=full]883864[/ATTACH] Here is a picture from the mirror field. The diagonal lines are latent die polish marks since almost all of the lines I saw were in the same direction and went clearly under the devices. The specks may be dust, impurities in the metal, or imperfections in the die. [ATTACH=full]883866[/ATTACH] This was the most interesting image of the three. The polish lines are still going in the same diagonal direction. But lookie here! There are some lines which are perpendicular. I only found these near the edge of the coin, which makes me believe they are early metal flow etch lines. They all have a consistent shape: a head pointed toward the center of the coin with a tail that gradually gets thinner. Logic and a very limited knowledge of metallurgy suggests that as the metal accelerates during striking, the metal etches deeper into the die. If that is the case, then this is clear evidence that metal flows from the rims inward, as [USER=112]@GDJMSP[/USER] says happens. [ATTACH=full]883867[/ATTACH] Now this coin is a Perth Mint 1 oz Star Trek silver round. The interesting thing about this coin is that it is a reverse proof. The following picture was taken in the field, which shows the granularity seen on the devices of the Sealand half dollar above. [ATTACH=full]883868[/ATTACH] When I placed my microscope over the brilliant devices, however, I saw a very cool image. With no flow lines or die polish to distract the camera, you can see the crystalline pattern of the metal. [ATTACH=full]883869[/ATTACH] While taking the pictures, I accidentally touched the surface of the brilliant area. To my horror, I saw that I had really messed up the surface. This goes to show just how delicate proof surfaces are. [ATTACH=full]883870[/ATTACH][/QUOTE]
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