Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark"
<paul.roark@v...> wrote:
snip
>...It may be, however, that the Cone sepia
> really is "un-toned carbon," but that it is milled to particle sizes
that
> are so small they fade faster.  Ironically, the smaller the
particle, the
> larger the surface area to volume ratio is.  This larger
> surface-area-to-volume causes faster oxidation, which is the cause
of most
> fading.

In essence meaning that ink terned as carbon pigment alone does not
necessarily indicate more longevity. We can't necessarily take that as
insurance, there's more to it.

snip

> Note that the Epson MSDS's make it appear that their black pigments
are not
> only carbon -- maybe not even predominantly carbon.  For example,
the Epson
> Light Black MSDS lists "carbon black" as < 1%."  "Proprietary dyes and
> pigments" are "< 8%."  Then, of course, there are "proprietrary organic
> materials" at "5% - 10%," and "glycerols" at "about 18%."  Water
makes up
> the balance.

Giving them the benifit of the doubt and assuming that only "carbon
black" and "Proprietary dyes and pigments" are image forming, only
11+% of the image is carbon black, and if "proprietrary organic
materials" contribute any optical density, even less.

> The color-based grayscale patches I've tested tend to fade faster
and shift
> green (indicating a relatively weak magenta -- which is consistent
with my
> general pigment reading). 

I'm curious which color inks did this. I've seen straight Ultrachrome
B&W prints that look decent with good profiles, but would be very
uncertain of them remaining neutral over time.

> While we might agonize the details, the bottom line is that our
> predominantly carbon (my best guess) pigments on buffered cotton
paper are
> very lightfast and archival (in dark storage).  The higher the
percentage of
> "carbon black" the more lightfast they appear to be.  (And I'm trying to
> find toning pigments that make this caveat moot.)

I suspect there is too much agonizing. I have many many prints made
from the original Sundance Piezography quad inks, thought by most to
be the devil's brew. These date back to spring of 2000. Though none
have been sitting in the sun, they have seen normal display conditions
on and off and date back to spring of 2000.
Though a few have lightened and reddened abnormaly, the vast majority
of them look great. Those that don't were unprotected for extended
periods and I suspect exposed to atmospheric contaminants, many may be
about sometimes in a working art studio and industrial air. This kind
of thing may really be our biggest problem, many unkowns, and I
suspect also relevant to yellowing coatings.
Tyler