Digital BW, The Print

Paul,

The UC inks may last 75-100 years, but the Enhanced Matte paper will 
begin to yellow at 30 years, at least according to Royce Bair at 
inkjetart.com; I quote him here:

"The Enhanced Matte image permanence drop was NOT in going from the
roll version to the sheet version (not a coating difference issue)
The 30 years vs. 75 years (with UltraChrome inks) and the 30 years
vs. 100+ years (with the Archival Inks) is due to paper YELLOWING.
Within about 30 years, both the roll and sheet versions of the
Enhanced Matte paper will yellow due to the paper's slightly acid
pH.  The image itself, will not start to show noticeable fading
until about 75 years (UltraChrome) or about 100+ years (Archival).

NOTE: this data would also apply to Epson's "Archival Matte"
paper, which is virtually the same paper as Epson's Enhanced
Matte.  Why didn't Wilhelm notice this 30/100+ years problem in
the beginning?  Probably because yellowing is not a something
can be seen as quickly as light fading, where this can be
simulated (accelerated) by increasing the light intensity, then
interpolating the data.  Yellowing can be simulated by increasing
temperature and humidity, but the reaction takes longer, and is
not necessarily able to be interpolated in a linear fashion as
nearly as light and time."

Dan