Digital BW, The Print

Ernst Dinkla <edinkla@...> wrote:

 
> The carts are 130 ml on the Z3100/Z3200

I was able to pull 140 grams of ink from the Z3100 PK cart.  At $67, 
it's more than I like to pay for ink, but a 30% dilution for "LK" the 
HP ink cost is right down where it ought to be, and at another 30% 
dilution for LLK, it's less than any commercially available ink.

> ... pump also stirs that ink content above it, ...

I thought HP would not let a settling problem go unsolved.

>... The Z models go in 
> sleep mode when idle but will awake several times a day to 
> check nozzles etc and it is likely that the pumps are 
> actuated then.

I suspect checking the nozzles is actually secondary to stirring the 
ink, but they probably don't want to advertise that issue.

> ... HP has a piëzohead design of its own 
> but decided to use a thermal head.
> 

They can, apparently, use semiconductor fabrication technology for 
the thermal heads, which is a huge cost advantage.


For the HP-based B&W inkset I'm considering, it looks like I'll end 
up with 2 dilution bases.  The target glycol & glycerol mix is the 
Epson MK 15% for each. To get there, however, I'll use more in a 
first 1:1 mix with the HP PK.  After that the same 15%-15% base can 
be use for the other dilutions, working from the 1:1 mix.  

Contrary to my comment above, I'm not targeting the LK-LLK standards 
at all (where the traditional 30% dilution is very close with HP 
PK).  I'm working initially to a simple 4-dilution spread: 50%, 20%, 
10%, and 5%.  That leaves 2 spots for K (Eboni or any PK) and a warm 
carbon toner in the Y position (probably MIS or UC K2 LLK for glossy 
or an "LLK" equivalent diluted UC MK for matte, which is my 
interest).  I do need a warm toner to overcome the HP PK's too-cold 
tone for my tastes.

The buffering with TEA and citric acid seems to work.  I dilute both 
to 10% solutions first.  Then a 10 TEA to 1 Citric acid ratio seems 
to hit the target pH.  

1% Edwal LFN wetting agent, in addition to the Photo Flo percentage 
used in the C6 mix, seems to give the final enough surfactant that 
it's printing smoothly in the 1400 -- on both matte and glossy papers.

I'll publish the complete formula later, but so far so good.

It pains me a bit to move away from a 100% carbon approach, but I 
think the settling problems with the Eboni/Carbon-6 are major 
problems for large format users.  (No problems with the desktop 
printers.) 

Frankly, the move to an HP based inkset allows me to use un-
brightened paper, which I vastly prefer.  So, while I won't be able 
to hit the 100% carbon target with this approach, the overall HP + 
non-OBA paper will actually be more stable over my lifetime due to 
the lack of those OBAs, which are by far the main source of tonal 
instability with either a 100% carbon or HP grey approach.

Paul
www.PaulRoark.com