Digital BW, The Print

well, as you know, the Aurora Natural is already more yellow. How will the yellowing of 
EEM effect the print itself? Also, which paper (with the R2400 inks) will be more fade 
resistant in an album?

any opinions on the Moab Entrada Natural vs. the Aurora Natural?

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark" <paul.roark@...> 
wrote:
>
> > Archival Matte and Enhanced Matte are the same thing. ...
> > In the USA it's all called Enhanced Matte.
> 
> It's now re-names (again) to "Ultra Premium Presentation Paper Matte."
> 
> 
> >I was under the impression that the Aurora would last longer 
> >(more archival) due to the fact that it was cotton and has no OBA's.
> 
> >As I understand it there's two factors in judging a paper's archivability:
> >1- image fading and 
> >2- yellowing of paper. Is this the case?
> 
> >If so, what does that mean for the two papers in question.
> 
> The main variable in fading appears to be the inks, not the paper.  Pigments
> are much more lightfast and resistant to gas (chemical) attack than standard
> dyes.  Epson Claria dyes are far better than the other dyes.  The pigments
> are also much less affected by the paper.  Some papers appear to protect the
> pigments more than others, but if you have a very good pigment ink, it'll
> probably do well on most papers.
> 
> Dyes can do reasonably well in fade tests if they are on special (e.g.,
> "swellable emulsion") papers, but it limits the paper choices, and they are
> still not close to the best pigments in longevity.
> 
> The yellowing is caused by at least 2 things: acidity and OBAs.
> Enhanced/Archival matte paper is acidic, which makes it inherently
> non-archival.  The acids cut the cellulose fibers, among other things.  
> 
> The OBAs (optical brightening agents) are dyes that absorb UV and re-emit as
> visible light.  As dyes, they'll fade, leaving the paper look more like an
> "un-brightened" or "natural" paper.  This will give the appearance of the
> paper yellowing, but it may not have any impact on the image fade rate.  On
> the other hand the best papers I've tested to not have OBAs in them.  I'll
> test the Premier Art Hot Press (the best fade test I've conducted and what
> Epson calls its most archival paper) against Premier Art Smooth Bright White
> at some point.  The Smooth BW is, apparently, the same paper, but with OBAs
> added.
> 
> Premier Art and perhaps other paper companies are also starting to use
> titanium dioxide to whiten paper.  This very white pigment is very
> lightfast, but it does not have the UV-to-visible light conversion
> characteristic of the OBA dyes.  As best I can tell the companies are using
> a mix of both TO2 and OBAs to get a paper that is bright but will not warm
> too much or too quickly.  While I resisted brightened papers for a while,
> I'm starting to use the Premier Art Smooth BW now with my carbon pigment for
> the same reason most use bright papers -- they can look very good.  I'm
> keeping my fingers crossed with respect to the OBA fading.
> 
> Note that the general source of the acids in paper is the breakdown of
> lignin.  Lignin is the hard part of wood that allows trees to stand upright.
> It's absent from cotton, which is almost pure cellulose (which is good).
> Lignin needs to be removed from wood-based papers to make them archival
> "alpha cellulose."  
> 
> Lignin itself is photo sensitive and will yellow.  To test for it in EEM I
> put EEM as well as a number of other papers on the surface of a UV light for
> about 100 hours.  Cheap paper samples yellowed badly.  The good cotton
> papers actually became lighter -- bleaching out, like Richard observed.
> Oddly, the EEM sample, paper back to the UV light, also bleached out.  That
> and a test conducted by a paper expert on a different forum indicate that
> the paper itself may actually be quite good.  The acidity has apparently
> been added intentionally for a better image quality.  (An Epson rep
> commented that the paper has a pH close to vinegar.)  For whatever reason,
> EEM does yellow relatively quickly.  Note that Wilhelm rates its life at
> about 110 years due to this, and stories from hot, high humidity areas
> indicate EEM can yellow in a matter of months in such environments.
> 
> The bottom line is to use the best pigments on acid free paper and
> understand that even good paper with OBAs will appear to yellow as the OBAs
> fade.  Some OBAs are better than others, but the more OBAs, the more likely
> the image will appear to warm with age.
> 
> Paul
> www.PaulRoark.com
>