Digital BW, The Print

Philip,

>  I was reading your writing about Carbon-6 just a 
> few minutes ago and starting realize my example of mix 
> might be too dark.
> 
> So the better mixes can be:
> 3 shades: 100% PK, 33% PK 10% PK
> 4 shades: 100% PK, 33% PK, 10% PK, 3.3% PK
> 6 shades: 100% PK, 33% PK, 16.7% PK, 8.3% PK, 4.2% PK, 2.1%PK
> 

In the C6 mix I used 33% MK for the darkest mix.  This was selected due 
to the ease of mixing.  It would allow those who did not have scales 
more easily mix the inkset.  Since it was close to the usual 
darkest "traditional" B&W dilution of 30% MK, I figured it's work well, 
and it does in older printers.  However, note that I've reverted to a 
30% Eboni mix for the k3 printers.  It turns out the 33% is too dark 
for k3 printers and some papers.  It results in inadequate separation 
or even posterization in the deep shadows when the Epson driver is 
used.  It appears this is caused by the k3 gray substitution 
algorithm.  The 33% mix works fine in the k2 printers.

This may not affect you at all with PK and if you're not using the 
Epson driver, but it illustrates something important.

While 30% is the usual dilution of PK to make LK, etc., and 30% MK is 
the "traditional" B&W darkest mix, this 30% mix is a considerably 
higher load than LK.  The LK density can be mixed from MK if about 18% 
MK is used.  

In terms of print density, however, to put the LK (18% MK) in 
perspective, recall that the dilution-ratio to print-density curve is 
very non-linear as the pigment load gets high.  Actually, this curve is 
very non-linear at both ends.  That explains how a 2% dilution can 
cover about 25% of the print range.

Paul
www.PaulRoark.com