I got my proof sets out and I noticed that all of the cents in the 2009 sets have some level of toning, or really discoloration. Is this a common problem with this year? Very few of the other sets from around this time show any problems. Maybe it is just the special cents for Lincoln's 200th birthday.
For once I can chip in with out the pics. I've noticed the same with my 2009 sets. I've chalked it up to the coins being copper and the reactivity of copper. Seems like there may have been some thing in the foam or the printed inserts that they didn't account for. The only other sets I've had were from the 70's and they didn't seem to have the same issues. I just checked and I don't have good pics of the sets, let alone the cents from the proof sets. If the thread lasts that long I'll seet what I can get tomorrow and post it.
I've heard it has something to do with the special composition for 2009. I had one set where unattractive toning/spots developed fairly quickly while the other one was fine. Some even develop attractive color (didn't happen with mine).
