In the spirit of this thread, allow me to share the very helpful response I got!
You may remember that I asked if any studies had been done on the effects of photocopiers on old photos.
One kind person led me to this very helpful website:
http://www.rlg.org/preserv/diginews/diginews2-5.html#technical
Hopefully, it will help someone else.
Bill Jackson
Senior Archivist
Harley-Davidson Motor Company
Milwaukee, WI