Digital BW, The Print

Paul Roark wrote:

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>Daniel Staver wrote:
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> Ernst wrote:
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>>... Black dye gets more
>>Dmax because it doesn't reflect the light as even the black ink has
>>transparency and the light penetrates the paper deeper and deeper while
>>it is still surrounded by black dye, it is then only reflected when
>>white paper is reached.  Scattered and what is left of the light it has
>>to return to the surface again following the same path through the black
>>dye.
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>That's an interesting observation.  I had not considered the transparency
>factor.  Some to consider the main difference between pigments and dyes to
>be the transparency of the final colorant.  However, in my reading on water
>color pigments, it appears that transparency is an independent variable that
>is also a characteristic of some pigments.  So, while carbon is rather
>opaque, other pigments have varying degrees of transparency.
>
>Perhaps this explains how the cyan or blue pigments with relatively low
>density actually increase the dmax of the carbon black inks.  If this is the
>case, then what we may want is the darkest pigment over coating that has
>high transparency.  Consistent with this, phthalocyanine (probably cyan
>pigment) has relatively high transparency.
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>>I'm already getting quite close to Generations black on matte papers
>>with Eboni so I'm not interested.
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>I agree.  Have you tried a dark cyan overcoat?
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I will try that. But an overcoat of cyan pigment on a black pigment 
layer isn't producing a black dye layer though.
One of my concerns with colored overcoatings is that they may increase 
metamerism. The Epson color head arrangement does something like that 
already with the KCMcmY order in undirectional mode, of course there's 
weaving done so it isn't Y totally on top and in bidirectional it is 
totally compensated. Getting a true overcoat in one printrun is not 
really possible.
In sikscreen color printing the color order can be varied for certain 
images, laying down yellow as the last color always gives a sheen on the 
CM(K) that I think will cause metamerism. But in that case it is a very 
pronounced thick layer on layer stack.

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>>There's a new pigment for paints recently developed that has an
>>extremely cracked surface, the cracks do something similar as the dyes,...
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>But wouldn't the cracks also let oxygen in and cause the fading to be
>faster?
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Any surface increase will result in extra gas-, humidity-, light- 
related fading. Not to mention staining by air pollution. But that's not 
different from micro porous coatings. But there are more Dmax effective 
micro textures than we have today.

The only way to achieve something like the above surface in inkjet 
printing is with a paper coating that has the same texture. The 
differences in Dmax of existing matte paper coatings with the same 
inkload show that there is more than just the inkload.

It wasn't actually a new pigment on its own but a surface coating 
system. Tried to find the original article (slashdot.org I believe) but 
failed so far. Found all kinds of interesting articles though and one on 
fungi in optical systems I was looking for some time ago but didn't find 
then :-)

Ernst