Digital BW, The Print

We can share some of the knowledge we have learn in our research to
make archival inks on the topic of stabilizing carbon pigments.

There exist at least two kind of carbon pigment currently used in the
ink industry. The first kind correspond to the pigments obtained in
the traditional way: lamp black, acetylene black, etc.
They need to be stabilized appropriately with a dispersant. There are
probably several hundred dispersant to do that: the most common in the
ink industry are acrylic resins. However, there are also natural
polymer that have dispersing properties. Specific examples of natural
polymer dispersants include proteins such as glue, gelatin, casein and
albumin; natural rubbers such as gum arabic and tragacanth gum;
glucosides such as saponin. Almost all of them need a biocide if you
need to keep the dispersion for long time. We successfully tested
thymol, which is a mild, natural biocide.
A very easy to obtain (not natural, as it is an acrylic resin)
dispersant is PVA (the common white glue).
The second kind of carbon pigments used to make inks are so-called
"surface-modified carbon black". They are obtained from regular carbon
black by oxidization of the pigment surface in sodium hypochlorite for
several hours at high temperature. After the treatment, the
coalescence of the pigments is much diminished and they need no
dispersant to be stabilized.

We suspect that MIS Eboni/Image Specialist 1082 use surface modified
pigments.

Hope these informations are of some help.

Daniela
www.mantinieri.com