Digital BW, The Print

Tom,

>Here's a link to an article on Kodak's newest paper which they claim to
>have 100 year life under 'home' display conditions.
 
>www.creativepro.com/story/news/20794.html?cprose=daily 
 
This could be the dye breakthrough I've been expecting.  I'm glad it's
Kodak.  (They desperately need a place in the new photo scene.)

Most of the color pigments in the inkjet printers appear to be what are
called "dye stacks."  That is, they are dyes that have been formed into
solid chunks of insoluble material, unlike the dye inks that are dissolved
in a liquid base (mostly water).  The only reason color pigments are more
light and gas fast is that they are larger chunks of matter that present a
lower ratio of surface area to mass than do the tiny crystals of dye that
form on the paper as the base evaporates. 

The swellable emulsion was one attempt to reduce the ability to gas to get
to the dye, and it was better than nothing.

What I've been waiting for is a way to turn the dye into a solid chunk of
material that was closer to the mass of a pigment, but only after the dye
hit the paper.  My thought was that an epoxy-like, 2 component system would
be a good model.

It sounds like Kodak may have found a solution that is close to this.  The
Kodak release states, "Using a unique blend of mordants (additives to "fix"
the dyes) ...."

The following is the best explanation of a "mordant" I found in a quick
search:  "A mordant is a metal with a valency of at least two. The two
commonest metals used in histotechnology are aluminum and ferric iron, both
with valencies of three. The attachment of mordants to dyes is by means of a
covalent and a coordinate bond."  (see
http://members.pgonline.com/~bryand/StainsFile/theory/mordant.htm)

I think Kodak has found a way to chemically lock the dyes up in, presumably,
relatively large and inert particles.

Now, I'm not saying Kodak isn't hyping this achievement, but their paper
sounds consistent with what I've been looking for.  I think Big Yellow's R&D
department has just raised the bar substantially.  Their test procedures
also look to be very thorough.

I don't think the new development will overtake carbon pigments (if -- big
if -- the Epson Archival pigs are 200 years, we're over 300), but I think
Epson's color pigment approach could be in trouble.   

Paul
www.PaulRoark.com