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<p>[QUOTE=&quot;BAJJERFAN, post: 2130932, member: 74330&quot;]Where do you think the silver chloride comes from? It occurs to this observer that the planchets/blanks when put through the annealing process aren&#039;t all that well protected from contact with oxygen which allows silver oxide to form on the surface.</p><p>It is this oxide formation that the hydrochloric acid wash is intended to remove. It would seem that this washing reaction isn&#039;t always driven to completion during the washing process with the net result that it is delayed only to be completed at a later time resulting in the milk spots seen. The other possibility is that the coins that DON&#039;T spot may not have ever had any oxide on them to start with, thus the washing had zero effect on them. Of course without access to the mint&#039;s processing details, most of this is educated precision guesswork.[/QUOTE]</p><p><br /></p>

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