Digital BW, The Print

Paul, you wrote:


> I now think the reality is that the FS/VM/PiezoBW blacks do have some dye
in
> them, but due to the co-solvent base, the dyes tend to "aggregate" (clump
> up) -- probably around the carbon pigments.  So, while the carbon may not
be
> coated like the Epson Archival resin coating, the dye is probably not just
a
> thin coating on the paper.  As such, the pigment/dye masses have a surface
> area to volume ratio that is closer to a pure pigment than would be the
case
> with a black pigmented ink that has some dye in it but does not have the
> co-solvent base.
>
> The reason the FS midtones fade faster than the black is probably that the
> black is diluted with a standard, non-co-solvent base that dilutes the
> co-solvent and destroys the "aggregating" function of the co-solvent.  As
> such, what little dye is in there burns off relatively rapidly.

For a special masking ink used on silkscreen films to get a washed touche
effect in the silkscreen print I've used medical carbon particles.
Norit makes several grades of that carbon powder. The size of the particles
that I used was around 50 micron (I had to sieve the carbon to get rid of
the smaller and bigger particles). This carbon is made for absorption and
will absorb a lot. When I mixed it with 2 quantities of PVA solution then
the next morning the stuff was more or less solid again. It could well be
that the carbon used in the inks has some absorbing characteristics, not to
the degree of the carbon I used but still enough. The dye mixed in will not
just stick to the surface of the carbon particle but penetrate as well.
Usually carbon in non-inkjet inks means lamp black. That isn't free of dye
like components as a result of its production. I have no clue what actually
is used in inkjet inks but carbon pigment comes in more than one form.

Ernst