Digital BW, The Print

Hi Ken,

>...I just had my
> first letter size print roll off my R280 using a 50/50 
> curve blend of a 3MK and a 3Y3K on Epson UPP (EEM).  
> Wow, WOW, WOW!!!!!  This is better than my darkroom work ...

I'm glad that inkset approach is working for you. I think it makes a 
nice, easy outfit to live with.  I like the idea of only 2 inks to 
mess with.  A CIS with only 2 bottles also works just fine.  (But 
agitate those bottles regularly.)

...
> - I saw some of your profiles were 3Y1K ...

Yes, it's real easy to make a 3Y1K profile.  Do a 1YIK profile and 
split Y into 3 by copying the curve to the other 2 Ys and cutting the 
ink limit for each to 1/3.  

When I use these with the 3MK, that profile utilizes the other Eboni 
slots.  So, I don't worry too much about that fact that I've 
overweighted the K position Eboni.  In fact, it may help, because 
it's easier to get a very steep K final curve either with the K boost 
or just using Roy's built in profiling system -- which I use whenever 
possible.  In short, making things easy is the theme here.

There is also a smoothness issue, discussed below.


> I decided to go with 3Y3K to mix with my 3MK assuming my K/C/M
> carts would be more likely to run out together this way. 

Yes, evenness of useage is a relevant factor and favors the 3Y3K 
approach. 

> Thinking
> about how the curves blend my neophyte mind couldn't think up an
> advantage to using 3Y1K instead.  
> Do you have a reason you like 3Y1K instead 3Y3K?

In addition to laziness, if all 3 Ks start at the same time, it's 
going to show more.  So, if you use 3K, it's best with a custom, hand-
made curve that spreads the starting points.  The 3MK blended with 
3Y1K does a good job of spreading the Eboni starting points.

> - First shot at my 3Y3K profile I did the standard ink 
> calibration procedure and came up with a Y density of 
> 1.8 (K at 100) which seemed to jive with what I thought 
> was the Y dilution of 2%.  I did a 21 step
> and it seemed the K was cutting in a bit early 
> (could see dot pattern more easily than I expected).

That might be accentuated if all 3 Ks start at the same point.

>  Then I noticed in your "start" profile
> and other YK profiles you have a Y density of 5 set, 
> so I did this and think I got better results.  It is clear 
> from my calibration print
> that the Y density isn't as high as 5.  Did you up the 
> density on purpose to postpone the entry of the K inks?  

I played around with several densities there.  I forget what all the 
factors were for the 5; it probably just worked.

> Any error in the ramp as a result of the "erroneous" Y 
> density would then be corrected in linearization?

Well, if the "error" is not too bad the linearization will correct it.

When I to test strips with different parameters fed into the program 
I print graphs of the un-linearized 21-step Lab L (density) ramps. I 
use Excel "charts" a lot.  I like to see a smooth ramp before the 
linearization step.  That is a significant factor in selecting the 
inputs.

> - I notice the 3Y3K profile is a bit warmer than the 3MK profile
> particularly in the brighter mid-tones.  What causes the shift, I
> thought the Y ink was just diluted K ink? 

Dilute carbon is simply warmer than 100% carbon.  See the comparison 
at http://www.paulroark.com/BW-Info/1400-3Y-3MK-PA325.jpg

The warmth seems to come from the light being "filtered" by the edges 
of the droplet or particle.  A solid mass of 100% carbon minimizes 
this. 

> Or is it the agents used to dilute it that give the tone?

There seems to be an element of this.  All of the pigments are coated 
with something, even if just a non-ionic surfactant.  This "stuff" 
can have a warm tone.  (Some of it may also burn off early and 
actually cause a slight cool shift in tone.)

>  Do you think that tone will shift with
> time if it isn't a characteristic of the carbon?

I don't expect a significant shift in tone.  Truth is, this carbon is 
so lightfast, I've never tested any of it beyond what would be the 
equivalent of about 13 Wilhelm years.  It just takes too long.  If 
the pigments are "rock solid" at that point (or actually earlier in 
most cases), I go with the data that the professional testers have 
developed to estimate what will happen, and I know of no test that 
shows us what very long term Eboni or other carbon tone shifts might 
look like.  

My tests indicate that the paper tone shift of brightened paper is 
going to be the dominant factor for a very long time.  (Even un-
brightened paper shifts tones slightly -- probably bleaching.)  I 
think it's safe to assume the print tones you see will be very 
stable, with OBA fade (warming) being by far the dominant factor.  
For long term neutrality, that's why I put 3MK on Premier Art Smooth 
(no OBAs) 325 at the top of my list.

Good luck with the 3Y3K approach.

Paul
www.PaulRoark.com