Ian,
 
Perhaps the most illuminating news comes from the chemistry departments of  
the companies that make these products. I got into a heated discussion with a  
colleague about ten years ago regarding the value of adhesing labels to the  
outisde of polyethelene bags (versus dropping acid-free tags inside the bag) 
and  telephoned the head chemist at University Products to inquire about the 
life of  foil-backed labels. The chemist said the adhesive can last for ten 
years, but  not much longer. That means the thousands of bags with foil-backed 
labels  attached to the front of those lab bags will start dropping off in ten 
years  (five now, since I had that conversation). The moral of the story is that  
conservation plans must include complete replacement of the CDs every three 
to  five years and the original document needs to be preserved in an acid-free, 
 dust-free, bug-free, cool, and moderately dry environment for long-term  
preservation.
 
Oh, and the chemist also warned me that most commercial inks will not  
survive 25-years. Pencil on acid-free paper is the best for long-term  survival.
 
Ron May
Legacy 106, Inc.