Reply to Thread

Message:: [QUOTE="GDJMSP, post: 4092260, member: 112"]I think you're missing my point, but that may be my fault for not making it clear enough. Even if you're correct and atoms can migrate through metal, I somehow doubt that because solids simply cannot move through other solids, but for the sake of argument let's say you are correct. When milk spots and or copper spots form on coins of .999 or .9999 fineness - we're not talking about atoms migrating here. We're talking about entire solid clumps of impurity, roughly the same size as the resulting spots, migrating through another solid. And that just isn't gonna happen as a result of the planceht being heated up. Wherever those clumps of impurities happen to be in the planchet, that's where they are going to stay. In addition to that, if it was just atoms of impurities somehow migrating to the surface during the planchet being heated, those atoms would then somehow have to manage to migrate further, possibly even sideways, then somehow congregate together and form good sized clumps before you could even see them. You can't see atoms, you can't even see molecules. What I'm getting at is we're talking about clumps of impurities that are at least as large or larger than the period in this sentence. And those aren't going to migrate through another very dense solid just because it gets warm during annealing. So yeah, I think it can be ruled out.[/QUOTE]