Digital BW, The Print

Hello Scott,

>The spaces are either Adobe RGB for an RGB file sent to ABW or 
>a custom Dot Gain that I use if a greyscale is sent to ABW.
> 
>My latest print just a few minutes ago, came out decidedly with 
>a green cast. I seem to have lost all the modest warmth that I 
>would usually get with ABW +2/+2 on the toning wheel.
>Discouraging.....

Steve is right about RGB/grayscale differences.  I wondered about that
in your original post, but your main questions focused on paper and
ink so I didn't say anything. But FWIW let me relay a bit of past
history about this.

Sometime between 3 and 4 years ago, before Eboni, the 2200 and UC,
when people were still struggling with inks that color shifted and
1280 "clogs from hell" threads were common, there was a lot of
discussion on the pros and cons of RGB vs grayscale, especially with 
RGB partition curves being a more dominant method of printing. 
Threads on this topic sprang up with regularity for a long time.  In
my own testing with BO printing I determined that the resulting prints
varied slightly in contrast and density, but neither was inherently
superior to the other.  Since Grayscale images were 1/3 as big as RGB
it was an easy choice for me.  Over time those threads disappeared and
other trends took their place.  I guess it seemed to me that the
subject had long since ceased to be an issue and using grayscale had
become part of accepted wisdom, so I was a bit surprised by your post.

The point of this is just to underscore what Steve said and that you
need to pick one way of doing it and stick with it.  There are enough
other variables happening, why add another.  And it's quite likely
that with ABW and color inks involved, the differences between them
will be greater than they were with BO printing.  You probably don't
need that headache.

Back to your original problem, it seems that several things were
changed at once, so it's hard to tell which one was most responsible
for the differences.  That's one thing I've learned: when
experimenting, change one thing at a time.  

As for differences in ink batches, I've already learned that ABW
settings aren't carved in stone.  I can expect to make minute changes
from time to time.  I now keep a short memo in each image with the ABW
settings listed, and I keep brief notes about any changes made (it's
possible that subsequent ink changes might require going back to a
previous setting).  

For paper differences, I use image adjustment curves to compensate for
that.  I save them with the image (un-flattened), with each curve
labelled for its paper name.  It not unusual to have to tweak one of
these for a new batch of paper.  It's just a fact of life.  For
example, for an image I print in different sizes I have separate
curves for 8.5x11 and 13x19 versions of the same paper, because my
current boxes of those are quite different in contrast.

A final thought: I keep a small master print of each image so I can
compare it with later ones to ensure they don't drift over time.  If I
print an image differently I want it to be a conscious choice, not an
unconscious result of changing materials.

I hope these thoughts are helpful.


Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm