Dave,
The Ammonia will surely take the green corrosion off the button and that's the main reason I use it. Like I said, just be careful and brush it gently. These Connecticut buttons were gold guilted and very often the green corrosion covers the gold guilt. I've dug many a green covered button that after a good soaking in Ammonia, it came out with 95% gold guilt.
I don't suggest using Ammonia on anything but brass and copper.
If you do use this process, clean the outside of the button first; then clean out the dirt from the inside. Just be super careful because when 2-piece or 3-piece (Staff Buttons) get broken, they end up with dirt inside them. If dirt can get in then so can water. Water and Winter is the killer of military buttons. If the button is excavated within the freeze line of the soil, then the moisture freezes and expands in the button causing cracking and further deterioration.
Although I can only see a picture, I believe that the button would benefit from some additional TLC.
I've been really tied up at work this year and have not relic hunted. Now that deer season ended last weekend, I don't have to worry about getting shot. So, i'm getting ready to make my mark and find some civil war relics.
After seeing your button, I just became energized with the "force." Mighty powerful old boy, but don't have to explain that to you now do I?
Warmly,
John
offer to buy his DFX
). Otherwise I'd be trying my luck too.
HH
I want you to think about doing a waterhunt with us soon.....would like to have 5-6 guys there so I can video it! 
