Hi Belinda, Though I've never had a problem with pearls or ivories, I did have darkening of older plastic-types, but that was only due to excess exposure when running about 100-sheets at high-speeds. I doubt if you'll have anything to worry about with a short flash for just a few copies of any one piece. The bleeding you mention is nothing other than oil-based (and organic material) which comes to the surface in changes of temperature and humidity. I've learned not to wipe this away, as it would be drawn back into the piece (why I don't know) on its own. Removal of these fluids will dry out the piece and casuse warping. The much older pieces must never be touched by water. This is one of the reasons we see many of the Monte-Carlo and Vichy chips in such poor condition. These pieces were scrubbed over and over (each evening) to remove glued-on security stamps affixed the evening before for tallying purposes. Also, the huge quantities of Monte-Carlo materia imported in the mid-80's were washed here in the States to remove what was sometims layers and layers of stamps. Sad, but true. I know hardly anything about Chemistry, so I'm unable to express and other additional information than what I have, already. Hope this little bit helps. I find no problems with the plastic-type jetons and plaques that were produced after WWII.

JB