Digital BW, The Print

David,

you guessed right. Ink limit is a prepress term and refers to the maximum a=
mount of 
ink that can be laid down safely on a given paper. There are assumptions be=
hind 
these numbers that make them rather approximate when it comes to inkjet (su=
ch as 
what kind of ink is used etc).

As for what 240% means: Each "color" or "plate" is assumed to reach its max=
imum at 
100%. So in a typical 4-color print (CMYK) the maximum that can potentially=
 be laid 
down is 400%. Your 2200 can potentially lay down 700% !! 

All this is more relevant to those who make profiles and can fine-tune the =
Undercolor 
Removal based on percentages like these. Otherwise, I don't know that I wou=
ld buy 
one paper over another based on a manufacturer's spec for total ink load.

For practical purposes in bw printing on the 2200.... the more pure black y=
ou lay 
down at the 100% end of the grayscale and the less of the other inks the be=
tter your 
dmax will be.  That would make the desirable total to something like 120%. =


Note that the actual amount of ink that corresponds to what we define in cu=
rves, 
profiles etc as 100% for any given jet can be internally limited by the pri=
nter driver - 
or not. If the driver offers no choice for ink limits, then printing a 100%=
 patch of pure 
black ink can make it run off the page, even  if the paper is capable of a =
higher load 
in %numbers. And if ink doesn't litterally "run off the page", it will all =
appear plugged 
up. 

In other words, when we call a digital value of 100% - or 255 - there is no=
 generally-
agreed-upon amount of actual liquid that comes off the nozzle and onto the =
paper. It 
depends on how much the hardware is capable of and what commands are sent b=
y 
the driver. Which makes the % value only relative, not absolute. 100% is va=
lid only if 
you test for a given ink and determine the maximum amount of liquid the pap=
er will 
take before it stops looking any darker. In that sense, all these percents =
have 
different meanings for inkjets than they do in the prepress world where ink=
s are off-
set from a cylindrical plate onto paper (and old-fashioned raster dots rule=
).

All this, of course, is masked from the end user when the Epson driver is u=
sed and 
proper media settings and profiles are chosen. But for best control in bw p=
rinting, we 
have to go where no color-loving, average end-user would want to go.


Antonis


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "David Wroblewski" 
<dawroblewski@y...> wrote:
> I've been looking at the specs for papers recently, and I've
> come across references to an "ink limit" for a paper--
> for example, the Photo Rag datasheet on the Hahnemühle web
> site characterizes the paper as having an "ink limit"
> of 240%.
> 
> I gather that this is terminology from the printing press
> world, and that it means how much ink (240% of what?)
> the paper will accept before it get soggy. Does it have any
> practical application in the digital b/w world of inkjet 
> printers? 
> 
> I've only ever worked with an Epson 2200 (Windows XP and lately
> QTR/Linux) so I assume that the media setting is the indirect
> control for this. Or is this indirectly controlled by the various 
> curves we use to print files in B&W? Maybe fancy rips allow one 
> to control this directly somehow? If so, is that useful in 
> practice?
> 
> Thanks,
> david