Digital BW, The Print

Philip,

> I am planing to mix multiple shades of b&w inks from Photo Black (PK) 
> for printing on glossy paper. I have a few questions:
> 
> Is photo black a result of mixed color inks?

MIS PK that is 100% carbon pigment in most of it's sets.  Those that 
are blended with color pigments generally are called "PKN" or the like.

> What is a good ink base 
> formula for mixing with photo black - I wish there is a version of 
> colorless Windex :).

MIS Glop is the base I recommend for their glossy inks.

> 
> What is a good ratio of ink base vs PK ink?

The standard dilution for PK to LK, and LK to LLK is 30% darker ink, 
70% clear base.  I've used ratios of from 1:1 to 1:3 with the Epson 
driver crossovers and had them work fine.

> For example,
>     3 shades: 100% PK, 50% PK, 12.5% PK
>     4 shades: 100% PK, 50% PK, 25% PK, 12.5% PK
>     6 shades: 100%PK, 75% PK, 50% PK, 25% PK, 12.5% PK, 6.25% PK
>     8 shades: Any benefits for that many shades?

The inksets with many shades often use one that is close to 2% black, 
98% clear base.  You'd be surprised at how dilute you can go.  You're 
examples are rather dark in comparison.  On the other hand, the 
standard UT-C (darkest dilute carbon ink) is denser than the 30% PK 
because it was based on the higher load MK, not the PK, since the early 
focus was on matte papers.  

Good luck with the mixing.

Paul
www.PaulRoark.com