TPG conservation of CuNi coinage
I have a rare coin which, despite spotting, is rather nice looking, so I plan to submit it to a TPG, as it is surely one of the better of the variety.
I'd like to be sure the spotting is stopped in its tracks before having the coin holdered. I have experience with the TPGs conserving gold, but not copper, nickel or silver. I'm not very concerned with trusting them to well-conserve silver without damaging it, but would like to know more before making any decisions about conserving copper or nickel, and especially nickel, in this case.
Therefore, I'm looking for feedback regarding short-term and long-term results from those who have had nickel coins conserved by either or both NGC & PCGS.
Can anyone chime in with their personal experiences?