Digital BW, The Print

>So there really is a difference between acid & lignin-free 
>alphacellulose and cotton after all? 
>I was under the impression that they had the same archival properties.

The main longevity problem with wood-based papers is the lignin, which is
the hard substance that allows the trees to grow tall.  Cotton has none.
The lignin produces acidic byproducts as it breaks down.  If the lignin is
totally removed, the resulting "alpha cellulose" and cotton-based cellulose
would, I believe, have the same properties with respect to longevity.  

Cotton fibers are longer, making the cotton paper better for some purposes.
This would include where bending is involved.  I think, all else being
equal, that the cotton matte papers also absorb the water better than alpha
cellulose.  The paper company reps don't necessarily agree with me here, but
I seem to see more blotchiness on alpha cellulose papers than on cotton
papers.  My observations may be the result of other differences, however.
An example of this would be the Innova-coated Permajet cotton-based "Alpha"
paper v. the U.S.-Innova version of the same paper that uses alpha cellulose
as a base.

I think the problem with cheap wood-based papers, including, apparently EEM,
is that the lignin is not totally removed.  Lignin is photo sensitive and
turns brown itself, regardless of buffering.  So, even if a paper meets the
standard of < 1% lignin and > 2% buffering, that lignin will yellow with
light exposure.

The old darkroom fiber-based papers were generally high quality alpha
cellulose, I believe. It can be good if well processed.

Paul
www.PaulRoark.com