QTR-Quadtone RIP

Hi Vincent,



>  I've been playing with variations on Roark's
>
[MIS's]

>  Eboni 6 (strictly speaking carbon 6 since I am using Roark's E6B base)
> with a 1430 (1400 family).
>


>
> Why should my K ink be 100% Eboni? Even printing black only I can get the
> same DMax (on Epson Hot Press natural) with a diluted K, say 90% or even
> 86%.
>

The optimum pigment load for a black ink is one of the variables that has
to be nailed down when designing an inkset.  It will vary with ink, paper,
printer type and speed.  Over time the MIS PK has gone to a more dilute
version (MP PK is denser than K4 PK).  Over the next month I'll be looking
at optimizing the load for a new MIS PKN (that I'm told greatly reduces
separation in wide format printers and differential fade -- we'll see).
 I'll have to test the papers that are popular now and the printer(s) that
I think are representative of what we'll be using most today and maybe
tomorrow.  It's not a trivial issue and it will always be a compromise.


> A more dilute K should force the printer to use larger drops which gives a
> more neutral tone (according to Roark's tests).
>

But the more dilute inks are warmer.  Sigh ...



> More generally, when designing an Eboni ink set, is there a rule for
> determining what dilutions to use? With the standard (100, 30, 18, 9, 6, 2)
> I find that the inks do not give evenly separated value / density curves
> but have gaps (eg. K and C) and nearly overlapping curves (e.g. Y and LM).
>
Actually, I find the QTR curves for the Y and LM are usually separated by
more than the M and C curves.  It may depend on the paper used.

While with 86, 40, 18, 12, 9, 2 the curves are more evenly separated which
> should make it easier to partition between inks.
>

Once you take control of your inks the way you have, you can customize them
for the precise paper and workflow you like best.  The numbers I used are
based on a standard 30% dilution per step, but then also based on matching
the matte and PK progressions.  C 30% MK.  With a glossy inkset, the LK is
about 30% of PK.  In Eb6, the M was set to a value that "matched" a
standard LK.  (The curves are not congruent, so one has to pick one point
to match.)

The warmth relative to dilution peaks at about the 18% on many papers.  The
most neutral is the MK.  The most neutral of the dilutions is usually the
2%.  I tried the just using Y and MK, but it left too much of a gap.

Have fun.

Paul
www.PaulRoark.com


[Non-text portions of this message have been removed]