Digital BW, The Print

This is my latest experiment with this un-diluted, relatively neutral Eboni
carbon core and the R1800.

 

Since the Eboni core is more neutral to start with than the other neutral,
non-blended carbon pigment inks, it might make an interesting starting place
for the relatively neutral tonal (color) space I tend to like to print in.
The more neutral the starting carbon core, the less color inks need to be
added to achieve even a more neutral print.  The fewer the color inks, the
better I like it.

 

With the previous variable tone inksets, to offset a yellowish carbon, I
used a blue toner.  I started mixing the blue toners from cyan and magenta.
Then, when R800 blue became available, I used it and cyan.  To avoid the
problems of blended inksets, I moved to separate LC and LM channels.  One
problem I have with this approach is that the cyan and magenta will fade at
different rates.  Most likely, the prints will shift green as the magenta
fades faster than the cyan.  (Compare the RIT magenta and cyan pigment fade
rates for MIS older color pigments at http://www.inksupply.com/rit.cfm  Over
about a 50 year simulated display life, the cyan was 5 to 7 times more
lightfast.  This strong cyan pulls the image tone into green as the magenta
fades.)

 

The first interesting toning variation to the multiple channel Eboni
printing I've been experimenting with on the 1800 is to use a bit of R800
blue as a single-color toner.  Basically, a tiny amount of R800 Blue makes a
more neutral, classic "selenium" looking print.  What I did is equalize the
maximum midtone (50%) values for Lab A and B.  

 

See the charts at http://www.paulroark.com/BW-Info/Eboni-Blue-PA270.jpg
These compare the spectral distributions of Lab A and Lab b.  (On the graph,
the paper white is on the left and the 100% black on the right.)  The top
chart is 100% Eboni.  The bottom chart is a QTR profile that injects just
enough R800 blue into the Eboni core to make Lab A = B = 2 at 50%.

 

This lowers the total chroma from 3.7 to 3.0 (according to my X-Rite
Spectro) and, to me, makes a print that I might favor in some situations.
The amount of toning can be varied via the ink limit and sliders in the QTR
and IJC. 

 

The total amount of R800 Blue ink needed to reach this point in a curve
point at 50% of (50, 13), with an ink limit of 2.  So, multiplying these
values, the R800 blue would be at 2.6%.  At this point the Eboni curves
total 9.4%, for comparison (but note that Eboni is probably a higher load
ink).  (The dmax for the carbon curves is at 82%.)   The more neutral curve
prints a 50% Lab L value of about L = 53, whereas the 100% Eboni core curve
at this point prints a 50% Lab L = 53.9.  So, there is little density that
will be lost due to any blue ink fade.

 

So one gets a slightly more neutral print to start with at the expense of a
slightly larger warm color shift if the print is ever displayed for very
long periods. 

 

Paul

www.PaulRoark.com <http://www.paulroark.com/>  

 

 

 

 

 

 

 



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