Digital BW, The Print

"grimmieoldfart" <grimmieoldfart@...> wrote:

> ... What does a Black Only neutral curve really look like graphed in Excel? 

>In theory if nothing else. In reality, I think it is impossible to achieve a truly compliant neutral curve because of the influence of the paper white and imperfections in the carbon inks.

True.  

 
> However, as Lab L* progresses from 0 to 100, does Lab a* and Lab b* remain steady at 0? Wouldn't it require both a* AND b* to remain at the 0 axis to achieve a true neutral?

As C. David noted, the warm-cool is mostly Lab B these days.  The more OBA's, the more negative (cooler) the Lab B will  be.  Natural paper will have a positive Lab B.

Lab A tends to be about +1 on my spectro.  It stays more constant across the density range than Lab B.

The Lab B will vary somewhat with the ink you're using.  They all, of  course, start at the  paper white.  The true carbon inks will all have some Lab B rise in the midtones, with Eboni being the least.  Then they'll get a bit more neutral or  cooler toward the 100% black.  Eboni might end up with a negative Lab B. 

The neutralized PK's vary depending on the amount of color they have mixed in.  HP PK will start quite neutral and have a cold shadow tone.  

MIS K4 PK, perhaps the warmest PK, on glossy  paper can have a Lab B rise over the paper white of 10 or  more.  On matte paper  it usually hits about Lab B = 8 at most.  Even this one, however, will head back toward a rather modest Lab B at the 100% black.

Epson has started to cool its PK and LK inks with what looks like cyan.  They will  have more modest Lab B's, but may stray very close to a negative Lab A -- too greenish for my tastes.

Paul
www.PaulRoark.com