Thanks to everyone for their comments about the Baden Baden Plaques. After Dave S. comments about the deteriorating Formaldehyde in the bottom chip shown below - I examined the Plaque and it definitely was showing signs of deteriorating in the Lunettes - shrinking, bubbles in the surface and a mild vinegar smell. In the past I had a bunch of older Monte Carlo and Curzon House Plaques that were really falling apart and smelling very strongly. I got rid of them as they were a possible health hazard.
My questions are -
1. Do they still use formaldehyde in making Plaques ??
2. IF no - when did they stop using formaldehyde in making Plaques ??
3. The Plaque in question was in use at some point from 1963 - 2001 according to the notes in the C G. Could the Plaque that is deteriorating have been made earlier than the one that is in "Good" shape ??
4. If the composition of the Plaques changed at some point between 1963 and 2001 should they be recognized as two different Plaques (one with and one without formaldehyde) ??
5. Will the "Good" Plaque eventually deteriorate ??
6. Can I preserve and stop the deteriorating by coating the Plaque with fingernail polish ?? I had heard about this process years ago but never tried it. Has anyone used this method to preserve Plaques ??
7. Is there any other way to preserve these Plaques ??

Any help on these questions would be appreciated.

Take care,
Jerry