Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Ernst 
Dinkla" <E.Dinkla@c...> wrote:
> 
> ----- Original Message -----
> From: "Roy Harrington" <roy@h...>
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Sent: Monday, March 10, 2003 8:55 AM
> Subject: [Digital BW] Ink Set Ideas and Questions (7500)
> 
> 
> >
> > All these new inks and ink sets have been very interesting.
> > I'm finally going to take possession of a 7500 this week, so
> > I have to order some inks.  I've liked the VM-Sepia inks for
> > my 1160 and just getting those for the 7500 is certainly an
> > easy solution.
> >
> > But, with 6 inks now and my QuadTone workflow I've got
> > more control and options than an RGB workflow.
> >
> > With the CMYK workflow I've gotten the best dMax by using
> > 100% black ink plus 100% cyan (dark gray) -- i.e. I can easily
> > specify 200% ink usage for dMax.   So my idea is to try for
> > using 2 inks that are black to get 200% pure black.  So the
> > question is what ink to give up.
> 
> Interesting message Roy.
> 
> There are however few inkjet coatings that allow 200 % ink
> without losing detail. Even with a linearised 9000 I usually get
> no further than 175 % on Hahnemuhle coatings. Wasatch 
SoftRip,
> the primary RGB colours mixed from CM MY YC. There's 
another
> reason not to go any further, with pigment inks you will not gain
> extra black nor in the case of colours extra gamut. The 
pigments
> are just too opaque, for colour where no light gets through to
> the substrate
> so you do not get filtered light reflected, for black where no
> light is lost in the depth of a dye pool it is reflected from the
> surface of the pigment particles. Paul wrote a message just
> before yours where he compared a double printed black with a
> single one and not much difference between them. At the 
colorsync
> list there was a short thread on the gamut gain with pigment 
inks
> and where the ink limits should be set before making the 
profile
> as for example a 100% cyan + 100% magenta doesn't deliver 
more
> gamut than a slightly lower percentages.
> 
> There's a difference between Paul's double printing and 
printing
> 200 % ink on the paper in one go. Inkbleed in the depth and 
width
> of the coating is increased with the last compared to the first
> where there's drying in between. The density will probably be
> higher with the 200% ink in one go.
> 
> There is however a good reason to add some dark grey (and in 
my
> case composite grey) to even the darkest black. With the 9000 
(
> and it will not be much different with the other models of that
> generation) you often get white lines in the black with pigment
> inks. That is gone with the addition of a low percentage of grey
> ink up to 000 RGB. Under Colour Addition so to speak. Before 
you
> start with less grey inks I would recommend to print some 
samples
> of black with details and check what is gained and what is lost
> in terms of density, smoothness, detail. For smoothness it 
may
> even be better to add small percentages of two greys into the
> black. If you really go for two blacks then I think you will not
> use 200% at all. Consider a gloss black and a matt black then,
> there are other advantages than density with that set.
> 
> Ernst

Thanks, Ernst.

One of the things that I'm not too sure about is "what is 100%
of an ink".   With all the different resolutions and variable dot
sizes,  it seems that 100% is arbitrarily defined as a maximum
amount of ink that maintains some linearity from 0% to 100%.
This is just from testing with an 1160 using epson drivers and
now using gimp-print drivers -- I don't have an inside scoop
on the matter.

I've just experimentally found with the gimp-print driver that  if
I output the maximum of 2 inks Black and Dark Gray (cyan)
I get a greater dMax.  So I'm guessing it would be even
greater if I output the maximum of 2 Black inks.  Certainly if
I try this and dMax tops off before 200% I can easily cap it
where ever is best.

Roy