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<p>[QUOTE=&quot;Oldhoopster, post: 2760793, member: 84179&quot;]I think you already proved it.&nbsp; You said:&nbsp; </p><p><br /></p><p><br /></p><p>“Now, couple that with the fact that those who have experimented with trying to get the black marks off the coins by dipping them, and end up seeing that the black marks sometimes come all the way off, and sometimes they don&#039;t come all the way off but do come partially off after dipping - and you&#039;re pretty darn sure then it&#039;s not because those black marks are &quot;bad alloy mixes&quot;. Because if they were, they wouldn&#039;t come off, or even partially come off !“</p><p><br /></p><p><br /></p><p>Depending on the composition of the inhomogeneous streaks that could be caused by improper alloying, the sulfuric acid and thiourea in the dip may react to completely remove, partially remove, or even leave the streak unaffected. </p><p><br /></p><p><br /></p><p>I also don’t think&nbsp; that the mechanism you stated for contact marks without damage is a major contributor.</p><p><br /></p><p><br /></p><p>You said:</p><p><br /></p><p>“…might be because it is light contact, meaning not heavy enough to cause damage to the metal and leave obvious scrapes and streaks, but still heavy enough to leave something that can be seen” </p><p><br /></p><p><br /></p><p>This is a possibility and some of the streaks may be caused by this but I would think the contact material would have to be softer than the coin to deposit metal on the surface and since copper, gold and 90% silver are relatively soft compared to other metals you would find in the equipment around the mint (Steel), I don’t see this happening much.&nbsp; If the coins are the same hardness (coin to coin contact), then I would think that getting just the right amount of pressure to leave a mark without causing damage is not very common.&nbsp; When I consider all the bag marks and scuffs seen of BU coins, to think that there would be a lot that do not cause damage, I don’t know?&nbsp; That’s just my opinion, but it’s something to consider</p><p><br /></p><p><br /></p><p>Hopefully, a couple of these proposed mechanisms can help explain what’s happening.&nbsp; At least it’s a little more than saying “trust me”.&nbsp; In reality, there are probably a number of mechanisms that come into play, with improper alloying being a contributor[/QUOTE]</p><p><br /></p>

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