Digital BW, The Print

Hello Roy,

>There seems to be an ongoing notion that there are two distinct kinds
>of B&W prints: some made with pure carbon inks and others that use
>color inks and therefore somehow inferior.  But all of the methods
>that produce neutral-tone B&W involve color pigments.  The majority
>is always carbon pigment, but they all have color pigment added to 
>give the desired color.  

In a recent phone conversation with Bob at MIS he expressed his own
doubts about the RIP approach, echoing my own concerns.  The
implication (as I interpreted his remarks) was that the amount of
color pigments (which he said are made of "various polyesters") used
in the RIP technique is greater than the tiny amounts mixed into the
carbon inks of gray scale sets (I don't know if anyone has actually
calculated the difference).  He said that the mixed in amounts are not
significant enough to affect the "carbon status" of the inks.  Paul
Roark recently expressed similar concerns (see msg #43963, 4/16/04).

Of course longevity is relative.  I don't remember exact Wilhelm
numbers, but I do recall reading that the carbon blacks outlasted the
color pigments in one of his tests.  If the cyan/magenta dots in a RIP
print last 70 years and the black lasts 100 then you have a 70 year
print.  Is that "archival" enough?  Will a gray scale ink print
outlast a RIP print?  Will a pure carbon Eboni BO print last even
longer?  Nobody seems to have a definitive answer.

My own tests give me doubts about pigments.  I have a Septone print
(multi-tone gray scale inks) on my windowsill that began showing signs
of fading at 125 days.  Right beside it is an Eboni BO print (both on
PhotoRag) that is over 150 days now with no signs of fading.   Of
course that's an unfair torture test (bright daylight and a small
amount of direct sunlight every day), but it nevertheless shows a
difference in the inks.  I plan to do a windowsill test on a UT7 print
when it's available.

So...what to make of all this?  I don't know, I just have doubts about
the colored dots.  If I'm going to have dots I guess I prefer them
to be all black <g>.  The only thing I do have some confidence about
is I can say that my prints are pure carbon ink prints and that Eboni
ranks among the highest (if not _the_ highest) in longevity ratings. 
Beyond that, I'm just waiting to see what happens next.

Do you know if there are there any gray scale inks without toners,
just dilutions of black carbon ink?

Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm