Digital BW, The Print

Carl,

>I thought about using a syringe filter when drawing up bulk ink for 
>re-filling carts (particularly bottom filling).  Something like these, 
>which come in different filter areas and pore size:
>http://www.hcl-intl.com/mall/more.asp?fmmore=12549
>What would be the best pore size to use?

These could be perfect.  I think I'll order 0.4 and 1.2 micron sizes and see
what happens.

I'm told the Epson head and damper filters are "1 micron."  I'm not sure how
accurate these statements are.  I don't want to clog these filters.  So, if
the Epson filter size truly is 1 micron, then I'm favoring 0.4.  

It appears to me that 0.1 is a typical "disclosed" (query accuracy) target
size for many pigments.  Smaller particles are said to have higher gamut and
are easier to keep in suspension.  Larger particles are said to have higher
longevity, but they will descend faster.  I assume a bell-shaped curve with
a peak at about 0.1 micron.  

In addition to the filtering, high-shear mixing might be needed first to
separate agglomerations.  (But I'm also wondering if filters can do this.  I
sometimes use my darkroom filter funnel to catch and then grind the large
"clunker" crystals in dry-packaged photo chemicals.)  

For a high-shear mixer, a modified, cheap blender might actually be better
than most of the commercial units I've seen.  Foaming, mixing, and
dissolving air into the inks is a problem.  So, I might see if I can fashion
a floating lid for a cheap, small-volume blender.  This lid plus the use of
the standard one might also make mixing in a nitrogen atmosphere easier.
(Nitrogen is cheap, safe, and does not dissolve in water.  My chemist
brother says processing in a nitrogen atmosphere is rather common in the
larger chemical industry.  De-gassing and keeping air out of the ink in the
first place are issues.)

Paul
www.PaulRoark.com 


_____________________

On Tuesday, July 20, 2004, at 12:56  PM, Paul Roark wrote:

> So, affordable 1 or 0.5 micron filters that
> don't soak up lots of (costly in low volume batches) ink are on the 
> list of
> things to find.  The damper filters and MIS's large format CFS filters 
> could
> be possible solutions to this issue.  As a practical matter, I might 
> just
> recommend that every large format printer use a CFS for filtering and
> agitation reasons.
>
> Any thoughts on these issues are most welcomed.
>
> Paul
> www.PaulRoark.com
>




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