Digital BW, The Print

"John" <jrnolly@...> wrote:
>
> Centifuging will not necessarily give you the results I think you want.

I wasn't really looking for color (lab a & b) changes.  My only concern with the carbon pigments is Lab L from settling.  I just stumbled into the Epson LLK Lab A variance. 

With respect to the Lab L, centrifuging the inks correlates quite well with the density changes I've observed in actual printing and working with printers.


>... we did some work with paper chromatography ...

Yes, that is how I first detected the color in our old B&W inksets.

 
> ... when it comes to settling, you will still have it occur 
> to some extent when inks are allowed to sit undisturbed.

Yes, but the rates can differ significantly.  That's what I'm looking at in making decisions that trade that off against other things, such as how well the ink will penetrate watercolor paper surfaces.  By knowing the settlement rates I've been able to design around dilute carbon's inherent issues with excessive warmth.    

Part of what I envision is a modification of the 7800 that would allow these lighter viscosities and smoother Arches printing -- if needed.  

> The carrier/co-solvent of course is of paramount importance here.

You've seen me trading off glycol for glycerin, as well as adding a new surfactant to the mix.  Glycerin's high specific gravity seems to really help with the suspension, and it's very user friendly.

The surfactants are very interesting...

Paul
www.PaulRoark.com