Digital BW, The Print

Alan,

>... My sepia concoction is for BO printing. I used Eboni with 
>archival color ink but will now switch to another pig black.

The advantages that occur to me of a BO printing method for custom color
mixers is that they would have only one ink to mix and the driver would do
most of the work of distributing the ink fairly evenly.  A big disadvantage,
however, is that all the color inks, especially yellow, that you add to the
black reduce the dmax.  

In the UT2 system, I set up the yellow position for the sepia and custom
colors so that there would also be only one ink.  Yet, mixers will have the
neutral/warm gray to add density when the custom mix is at its maximum
density, and the separate black will be there to get a dmax as good as any
other print/inkset.

Of course the next step with the UT2 approach is to support the 2200.  The
separate carts will make it very easy to change custom mixes.

The dark sepia curve I made for EEM is a curve that can be modified very
easily for any custom ink in this system.  The custom ink carries the entire
image all the way to about 70%.  No other curve is involved until that
point.  At that point the sepia runs out of steam, so the un-toned gray ink
starts to supplement it.  I let Epson handle the cross-over.  There are no
reverse slopes and nothing complex at all here.  Finally the other/cool ink
curve is pulled in only to turn on the black.  

This is such a simple curves approach that any user can modify it to fit the
density of a custom ink by just visually moving the points up or down to get
the 5% patches to match a standardized step wedge the user has printed out
previously as a reference.  There is only one point to move per step.  The
starting point of the un-toned gray is simply moved to coincide with where
the custom mix hits full-on.  This makes for easy visual profiling.

I hope this type of approach (especially with the 2200) will open up custom
mixing to the same types of people who used to like to mess with darkroom
chemicals.

> I have MIS black ink going back a year or so 
>(including 'double black') and should probably dump it, no?

I'd dump it.  By the way, be sure to agitate bottles before loading or
mixing.  All these pigs settle.  Note the Epson instructions about such.

I'm glad to see others out there like to mess around with custom mixes.  I
hope my efforts encourage and simplify this.  I have always thought of
messing with B&W chemicals as part of the fun and a source of creativity.
Combine this with the Photoshop curves workflows and ability to use, for
example, a standard neutral tone in one area and the custom tone in another
selected area, and the B&W printer has a lot to play with.

Paul
www.PaulRoark.com 


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At 02:06 PM 1/8/04 -0800, you wrote:
> > I'm testing a sepia ink mix made from MIS M, Y, and Eboni black.  ...
>
>Beware mixing different ink families.  They can be incompatible.  Eboni is
>particularly sensitive and will precipitate unpredictably in all of the
>available bases I've tried.  (Epson matte black is about the same.)
>
>It's safest to, for example, to stay with a family of inks that are
>engineered to be together.  I've been using the MIS 7600 family for the
inks
>I've been mixing lately.  Sadly, this family does not include Eboni.  The
>only reason we can use it is because it is in a separate jet.  The MIS
Photo
>K, however, is in the 7600 family.  The older inks -- MIS VM, FS, original
>Archival (not GP) do well with the older MIS base.  The 7600 family,
>unfortunately, uses a special base that MIS might not sell.