AirmetTango
Forum Supporter
I run mine for hours to get them that clean, and also put along with gravel, dawn & water, some generic window cleaner (cheap stuff for the ammonia). It takes about a full day to get them real clean and sparkly.
The other thing I did was to pour off the dirty water about halfway through and redo the whole shebang.
Thanks for the extra info! I'll try the cheap Windex to see how it does - the ammonia is probably a key difference, plus the added time. I also see that another thread mentioned using some Borax:
http://metaldetectingforum.com/showthread.php?t=248641. It might be worth giving that a shot as well.