Digital BW, The Print

"Larry Heath" <lgheath@...> wrote:
>
> I have an old home made Ball Mill that should do for mixing/grinding, with the Daniel Smith product  as a starting point. I called Smith and Company, and they don't have a clue as to size other than very fine, I will see if I can get a size distribution, as is, as soon as I can. I have access to a pair of particle/cell analyzers where I work that should give me a good estimate of mean size and distribution of base stock and then what I can whip up. For a high concentration base stock, I think I will start by trying a 1 to 1 or 2 to 1 mix of your clear base C6a formula and the Smith carbon product with 15 lbs of 1/4" chrome balls (SAE 52100) milled for 5 hours at 200 rpm, and see what I end up with. Should be fun.


> 
> One last thing Paul, then I will go away and leave you alone for a while, could you expand on the bit about the "appropriate dispersion coating"  just a bit?  As in chemicals reacted with and covalently bonded to the carbon particles, or as in specific wetting agents to prevent particulate conglomeration, or something all together different?

My understanding is that some type of dispersion coating is usually applied in the ball grinding.  Steric or electrostatic appear to be the 2 basic types.  HP has combined them in what it calls "electrosteric."  See http://h10088.www1.hp.com/cda/gap/display/main/index.jsp?zn=gap&cp=20000-20058-20744-20843^27752_4041_100__

The traditional steric dispersion solution was gum arabic.  Most of our inkjet pigments appear to use electrostatic methods.  With these they do appear to be bonded to the outside of the pigment particle.

See also http://www.nanoparticles.org/pdf/Kowalski.pdf for some interesting information.  Some think Cabot is one of the ultimate sources for some of our pigments.

I played with gum arabic (carried by Photographers' Formulary) to see if I could slow the settling of Eboni.  I achieved a marginal improvement, but it also warmed up the mix.  So I dropped the effort and decided to just rely on agitation of the carts (which appears to be working without any negative side effects in the 7800).

Good luck with the experiments.  (If you get it to work, I have some special pigments I'd like you to try.)

Paul
www.PaulRoark.com