Digital BW, The Print

Roger Sopher <portlyfox@...> wrote:


> Kind of sounds like eboni has a small net negative surface
> charge  and a relatively large particle size. 
> That would tend to keep the particles in
> suspension when fairly concentrated and allow for a 
> more rapid sedimentation when relatively dilute.

That's exactly what I suspect.  The various forces that seem to be at 
work are effective at different distances.  There may be a specific 
distance at which the matrix of particles are in relative 
equilibrium, but when diluted that average distance is too much.  So, 
they tend to settle back into the more stable, denser matrix.

> One sees the same phenomenon with red cells.

The centrifuge I'm using is a used medical lab desktop unit.  I 
assume blood separation was it's main purpose.

> The matrix effect of the suspending liquid can influence 
> the surface charge ...

I've tried to find a different base mix that would help, but so far 
without success.  Frankly, I think the supplier is in a better 
position to know which way -- if any -- to go in this respect, so I'm 
not going to put more effort into dilute Eboni.  It's a very nice 
100% MK, and the diluted Eboni mixes work well on the desktop.  Wide 
format diluted Eboni, however, is not recommended (even though I'm 
still using it).

Paul
www.PaulRoark.com