Digital BW, The Print

I thought I understood from an e-mail from Jon Cone and his reply to 
Clayton Jones that the K7 did not contain any color pigments, but 
only Carbon and that the 'tone' was controlled by such proprietary 
things as particle size, etc.  I am inviting correction and/or 
clarification on this, however...

Michael Vendrell

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, hogarth@s... 
wrote:
>
> Paul Roark wrote:
> 
> > Bruce wrote:
> >
> > > The main disadvantage is the possibility of
> > > differential fading over time pushing the print's tone warmer 
or cooler
> > > than you intended.
> >
> > No, there should be no significant difference here.  I believe 
the K7 inks
> > have differing amounts of color pigments mixed in.  I may be 
wrong 
> > here, but
> > I simply don't know of any pure carbon pigments that can print 
neutral 
> > over
> > the entire range of densities we're interested in.  It'll really 
take
> > controlled, comparative fade testing to see what, if any, aging 
> > differences
> > there are from these inksets.  The differential fading problem 
occurs with
> > color inksets that attempt to make a gray tone from color inks.
> >
> > A "neutral" tone that is composed of predominantly carbon will 
usually 
> > have
> > some color pigments mixed in.  These will fade faster than the 
carbon, but
> > the carbon also shifts color.  So, there will be color change in 
either
> > case.  What usually dominates in a reasonable time span (like 
one's 
> > expected
> > life span for normal display conditions) is the warming of the 
> > carbon.  (If
> > you're using brightened paper, the burning out of the optical 
brighteners
> > may be the largest change -- which is a big reason I prefer 
paper with no
> > OBAs.)
> 
> First, I don't know the compositions of the various inks. I don't 
see 
> anything on the InkJetMall site that uses the words "carbon 
pigment" 
> however. I'm not even sure I now how a carbon pigment ink differs 
from a 
> pigment ink. Probably in the amount of carbon, but I have no idea 
where 
> that line is drawn.
> 
> Second, I didn't say there would be any differential fading. I 
said 
> there was a possibility of differential fading. It stands to 
reason that 
> the possibility of differential fading would be greater for the 
inkset 
> with the most color pigments. And a variable tone inkset is going 
to 
> have to have more color pigments than a fixed tone inkset. It's 
the 
> color pigments that provide the "variable" in the variable tone 
inkset 
> after all.
> 
> That doesn't mean that the variable tone inkset will exhibit 
> differential fading. That the possibility is greater doesn't mean 
that 
> the actual amount of differential fading will be noticeable or 
> objectionable.
> --
> Bruce Watson
>