Digital BW, The Print

Paul Roark wrote:
> Ernst,
> 
>> ...
>> The line below the molecule structure pictures says:  Epson\ufffds
>> newly developed Claria ink is much more resistant to light and
>> ozone thanks to its tightly clustered pigment molecules.
> 
> This says to me this ink is, in fact, a pigment ink.  Here's a potentially
> random thought: is this Epson's entry into the un-coated pigment market?  Do
> you suppose they've noticed the un-coated pigs have lower bronzing and they
> can't really solve the problem with their coated UC pigs?  So, they enter
> with a particle size that is so low that they get dye-like transparency and
> non-settling, but with pigment like lightfastness.  Calling it a "dye" may
> be a marketing approach to signal its superior performance on glossy paper.

Bronzing is a complex thing but the smaller the pigment 
particle the easier the penetration of that particle through 
the top layer of the coating on gloss paper. Either they can 
not encapsulate the particles due to their size or structure, 
on the other hand it may not be a good idea to encapsulate as 
they get too big to get through the membrane. The 
encapsulation on the K3 and the HP Vivera particles is there 
also to prevent the particles to clump in suspension, they do 
not attract one another due to the potential on the surface. 
So there's more done than just making them smaller. Another 
molecule is created as well as is mentioned in this line:

"To counter this, the researchers created new chemical 
formations by adding additional atoms to the dye\ufffds basic 
molecular structure, and then engineered the molecules into 
tight clusters. This not only strengthened the ink\ufffds atomic 
bonding, better protecting it from the effects of light and 
gases, but also improved the quality of the ink"

I don't think you can make another colorant without changing 
the molecule structure so that's obvious but they possibly hit 
on something that wasn't possible before but suits water based 
inkjet printing inks well.

> I wonder also if the, presumably, very small particle size, but still rather
> good, pigment-like stability, indicates that the particle size to
> lightfastness relationship is not linear.  Apparently some of these
> substances simply become transparent when they oxidize.  If that is the
> case, then they may still function as barriers to oxidation of interior
> molecules.  If that is going on, then it makes sense that there would be a
> non-linear relationship between size and oxidation rate.

That non linearity is something I also thought about but I 
think they did more than making the particles smaller. I doubt 
they can count on the positive filtering effect of oxidised 
particles, smaller particle size means more total surface area 
if compared to bigger particles and that usually gives more 
fading to light and ozon. Anyway when layers become oxidised 
and get transparent it would result in less chroma, even if 
neutrality in the print is kept it would be noticed in 
Wilhelm's results. I really think that they found something 
that allowed such small particles to be stable.

What intrigues me most is the lower Dmax Greg reported if 
compared to dye inks on matte and even K3 on matte.
If the black is also pigment based and has a very small 
particle size there may be something going on that I remember 
from some silkscreen ink research. The smaller the particle 
size and the more uniform that size (shape and size) the more 
difficult it becomes to create an opaque black ink. That has 
to do with the stacking of the particles, for opaqueness you 
need some non-uniformity. Something that is found in film 
grain structure too.

We discussed the Dmax of black dye ink in the past and I 
mentioned that light more or less drowns in black dye prints, 
like a black pond you look in at the right angle so the 
surface doesn't reflect. With bigger pigment particles 
opaqueness is created to a degree so white paper underneath is 
blocked but density becomes never more than the reflectance of 
the pigment particle surface (+ encapsulation) allows, laying 
down more ink the Dmax even decreases, something that is 
related to bronzing. I guess that the smaller uniform black 
pigment particle that works nicely on gloss papers considering 
gloss etc doesn't have the dye quality to create good black on 
matte paper (pond wise) but also isn't able to do it in 
pigment style with opaqueness. The last could become better if 
more ink is laid down if that doesn't result in bleeding. All 
speculative of course.

> Yes, the Epson heads, however, appear to have the advantage of variable dot
> size and smaller drops.  So, smoothness may be where the piezo head
> technology will have its advantage -- which is just what we see in the 260.

With the new HP and Canon wide format models another approach 
has been taken, thermo heads can be made with droplet size 
variation but it isn't an advantage in this case. There is 
just one droplet size per ink on the HP Z3100/2100 and they 
used a small one for most inks: 4 pl. That's close to the 
minimum droplet size used on the existing Epson wide formats. 
The result is that the print will be smoother in all mixes and 
gradations than Epson's K3 wide format prints as the last will 
use the bigger droplets when more ink is needed. The HP and I 
guess the Canon (though a bit coarser) will mix everything 
with that fixed small droplet size. The dithering, weaving 
pattern is adapted to that system. On the HP, the matte black 
and the gloss enhancer heads use 6 pl, the first one to get 
the bigger matte black particles through the wider nozzle, the 
second one to get more varnish on the print and create an even 
layer. The Epson wide formats right now will be smoother in 
the high lights where the 3.5 pl may have a small advantage 
(it also depends on the LM,LC, Y and LLK ink density of the 3 
manufacturers) but will not have an advantage above that 
level. It is interesting to see that the 3800 seems to use the 
smallest droplet over a longer range too than the older K3 
models do.

My bet is on countless many nozzles that squirt at 20Ks 
countless many small droplets. An interesting HP development 
is a static single array inkjet head that squirts pages at 
their full width without the head moving. See Edgeline 
Technology. It would be a much more expensive head in pi\ufffdzo 
technology.


Met vriendelijke groeten, Ernst


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