Re: Designing ink sets
Re: Designing ink sets
- Subject: Re: Designing ink sets
- From: Steve Kale <email@hidden>
- Date: Tue, 07 Feb 2006 16:41:08 +0000
- Thread-topic: Designing ink sets
Hi Ernst
You will know that my thinking is not constrained to conventional pigment
ink formulations. The question arose following a conversation with a
certain ink designer you and I both know. I had given feedback in relation
to the inks I had tested that the (K and LK) greyscale components were too
cold. It was then mentioned to me that the feedback from an extensive
survey was that people DESIRED slightly cool greyscale inks in a colour ink
set. I can not imagine how that would be beneficial in any way. If they're
cold then colour management or RIP must throw yellow and magenta in to warm
them up (in the same way that warm carbon inks need to be cooled). Hence I
wanted to check my conceptual footing that, given a free hand, it's
desirable to have as neutral as possible greyscale components in a colour
ink set. That is, that such an ink set would certainly be easier to manage
and likely more successful from a colour management, driver, RIP
perspective. Of course this "preferred starting point" would then need to
meet the challenges posed by the "physics", which would in turn be governed
by the properties of the materials used to make the ink. I'm wondering if
there is a rational argument for a different "preferred starting point". I
hope this makes sense.
Cheers
Steve
> From: Ernst Dinkla <email@hidden>
>>> I have a general question with regard to ink set designs, specifically with
>>> respect to the colour of greyscale inks used as part of a colour ink set.
>>> Am I right to say that good colour begins with good greyscale generation and
>>> that as a rule one would prefer K, LK and LLK inks which, when forming part
>>> of a (8 ink) colour ink set, which are as neutral on paper as can possibly
>>> be? I understand that this would, amongst other things, make profiling
>>> easier and images less prone to colour shifts. If I am wrong on this could
>>> you please explain why. Even if the foregoing is correct, are there
>>> circumstances when one would purposefully deviate from neutrality in the
>>> greyscale inks?
>
> Paul Roark uses a mix of an R800 blue and cyan to pull the MIS
> carbon black to neutral. Cyan only would make it too green.
> Cyan + magenta works too but the magenta fades faster.
>
> There's an advantage to start from a warm black in the sense
> that you do not need yellow and magenta to pull it to the
> neutral axis. The last two are more prone to fading than the
> black and cyan. When the first Epson UCs were introduced it
> was also thought that less yellow in the mixes would reduce
> metamerism. There are doubts about that. The UCs were mainly
> used on 7 head systems with the extra grey, the lower
> metamerism may be more the result of the extra grey ink and by
> that less composite grey. The Epson 10600 is the one that may
> reveal whether it was the lower yellow quantity or the lower
> composite grey amount that gives less metamerism. The term
> metamerism as used in print shop talk.
>
> I think the question is a bit theoretical. So far the real
> neutral pigment blacks fade to warm carbon black faster than
> many color mixes. The outer shell of the black pigment
> particle that has been colored is the first to go. The same
> for hybrid pigment/dye mixes. Cone's first quad inks and alike
> have shown that. Whether the warm carbon black is an advantage
> in color management and fade resistance or not we probably
> can't get better black pigment particles anyway.
>
> A neutral pigment black that would fade to warm black but is
> accompanied by a composite grey with a yellow-magenta mix that
> fades as fast is another option. More complex though and the
> 100% black would still shift to warm black in time if you need
> a high Dmax there at printing time.
>
> Ernst
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