Digital BW, The Print

"Paul" <paulmwhiting@...> wrote:
>
> 
> ... when we use cartridges that contain a diluted Eboni (diluted with a clear base fluid, no color), with various concentrations in each cartridge, is that also known as 100% carbon? Or does 100% carbon mean using only cartridges with undiluted carbon?


As long as the image forming substance is carbon (no color added), I call it 100% carbon pigment.  

Eboni MK is carbon at a pigment load (pigment weight relative to base/liquid weight) of about 20%.  (I don't know what Eboni's exact load is.  Some MKs are about 22%.)  When Eboni MK is diluted, the load or ratio of pigment to clear base decreases, but it's still only carbon pigment suspended in base.  When any of this is printed the carbon stays on the upper parts of the paper/coating, and the base is pulled into the paper/coating.  The pigment particles on the paper upper surfaces that form the image are all carbon and all the same in Eboni-6 and in Eboni 3-MK.

A relevant issue related to fading is whether the more dilute versions of the 100% carbon pigment inks fade faster than the MK.  With dyes it was generally believed that the more dilute mixes faded faster than the more concentrated mixes.  The crystalline structure on the paper that was formed by the dilute dyes was thinner than that formed by the more concentrated dyes.  These thinner crystalline structures, apparently, more easily allowed oxygen to reach the dye crystals and attack them.  Fade is, generally, oxidation, usually induced or accelerated by light.

The more dilute Eboni mixes have not been test at Aardenburg-Imaging.  However, Jon Cone's Piezotone Carbon Sepia has been tested, and it has a variety of different dilutions in it. (The Museum MK appears to be a different  pigment than the midtone inks.)  To see how the different dilutions of that inkset performed, I graphed the delta-e for the different density patches.  I also graphed the density v. delta-e for your sample of the 3MK Eboni inks that have only the higher concentration Eboni MK as the image forming substance.  The graphs are posted at http://www.paulroark.com/BW-Info/CarbSepia-Eboni3MK-density-delta-e.jpg 

The graphs look rather similar (ignoring the Museum MK).  The papers are different, and the 3-MK version is sprayed (and we don't know what that does with carbon), but the basic shapes are the same.  When the bumps as smoothed, the bottom line is that the paper is the most unstable part of the package, and the carbon -- low concentration or high concentration -- is very stable.

(I don't know what the story is with Museum MK's higher delta-e, but I believe the midtone Carbon Sepia inks are not simply dilute Museum MK.  If I'm wrong here I hope someone will correct me.)

Paul
www.PaulRoark.com