Maybe use the eraser first to remove those most prominent milk spots, then cloudy ammonia to restore the lustre?
i tried this with a clean soft eraser and found this: -for the new 2011 coin with a more matt finish it worked well. -for the 2010 coin with the polished surface i found it did more harm then good, but my milk spots are not that bad to begin with.
Drutter reports on this today... [youtube]http://www.youtube.com/watch?v=7sJSwKe5Ev8[/youtube] Link : http://www.youtube.com/watch?v=7sJSwKe5Ev8
I have basically designed a system on paper that uses "pressure" without actually touching the surface of the coin. When I have the money and time to build it, I will see how it goes. Of course I wont know if it works until I try!!
I had an idea that utilized surface scanning, a 3D model or surface depth map of a coin and precision picosecond pulsed lasers for micro polishing and surface redistribution which should result in removal of AgCl and contaminants, and elimination of any micro recess caused by consumption of the silver by the milk spot (see electron microscope images from the Perth mint). Then I realized it would be ridiculously expensive. [youtube]http://www.youtube.com/watch?v=AR5cpuWHD1M[/youtube]
Realistically speaking... If there was a cost-effective way to remove milk spots from silver coins without abrading the surface of the coin and thereby destroying any value beyond spot, the major and most notorious milk spot-producing mints would be screaming the happy news from the highest towers. The fact that no such announcements have been made tells us everything we need to know about traditional "remedies" like erasers, jeweler's cloths, files, rasps, wire brushes, etc...
And on the off-chance that any of these coins happen to survive for another century or three, and somebody then decides to get 'em slabbed? Will be in for a bit of a disappointment with that non-numerical Details grade. Do the future generations a favor & leave them spots alone, folks..