Digital BW, The Print

I too would like to see how linear the rate of fade is.  I have no idea how
difficult it would be to record this sort of thing in your next set of
tests.  I seem to remember reading a Wilhelm article which discussed the
importance of the length of the stand-down period between printing and
starting the fade test.  I certainly understand chasing the best possible
but if the extra fade of Adv B&W K3/K4 is "acceptable" then I would find the
convenience of Adv B&W and colour printing retention to be hugely
beneficial.  So if the bulk of a 0.7L* fade differential occurred at the
beginning of the test and subsequent fading differential was trivial then
I'd be very happy with that.  We also have to remember that a 0.7L* fade
rate differential on a 50% patch is trivial at best.  You are talking about
density changes of around 0.01 to 0.02 only!

I also think it would be useful to run a test on the individual K3 vs K4
inks - ie a colour patch of each ink.  While we do of course print greyscale
which involves blending these inks I'd like a sense of whether or not MIS K4
is better across the board or whether certain inks perform better than
others.  (This would of course be extremely helpful for the colour guys as
well.)


> From: Paul Roark <paul.roark@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 28 Dec 2005 12:16:22 -0800
> To: <DigitalBlackandWhiteThePrint@...m>
> Subject: RE: [Digital BW] On Paul's MIS vs. K3 fade tests . . .
> 
> Walt,
> 
>> ... I too am uncomfortable, in principle, with the use of
>> pure color inks in BW printing (as with the K3s).
> 
> I'd still like to see some double blind tests to see if people can sense the
> difference visually.  I'm a bit skeptical about that.  So, if there had been
> no significant fading difference, I might well have just gone with the
> straight k3 approach.  There is no doubt that having color available
> occasionally is useful even for strictly B&W guys like me.
> 
>>  What I wanted was a sense of the real
>> world significance of a L* 0.70 difference in fade given your
>> light/time exposure.
>> 
>> This question arises for me partly because such an absolute
>> difference is very small...
> 
> Yes, all of absolute fade amounts were small.  The results are only
> significant if put into the context of the relative fade rates.  There, in
> the extreme case of the ABW mode k3 print v. the MIS UT dedicated B&W test
> strip, there was a 3x difference.  On the other hand, the significance of
> this fade rate difference depends on additional assumptions, such as whether
> the rates we see in initial fading will continue.  So, there are some
> variables here that are simply not completely known.  For my own purposes, I
> think the results are significant, but I would never go so far as to say my
> tests "prove" that the dedicated B&W inksets are three times as lightfast.
> I've simply seen enough evidence, including but not limited to just this
> fade test, that I think it's now worth my time to take the next step.
> 
>  
>> ... I don't know what you estimate your exposure to be
>> relative to the total display life of a print.
>> Is the difference you report just the "beginning of the
>> story,"...
> 
> Clearly what I'm reporting is just the beginning of the story.  Based on my
> best measure of how bright the light is, I've tried to give some equivalence
> to "Wilhelm years" of display.  However, not only is my equivalence a rough
> estimate, but also I'm not sure how many really trust that the "years"
> Wilhelm uses are realistic.  (Then again Kodak assumes even less light
> exposure for its calculations.)
> 
> Put in the setting of traditional collector's skepticism about inkjet
> technology, I'm just trying to get the best performance I can relative the
> Epson pigments, which Epson will promote using Wilhelm data.  I'll then
> simply do the best I can to leverage off those numbers, trying to avoid the
> issue of what the "life" of a print is.
> 
> 
>> Incidentally, what are you measuring?
> 
> I use a 50% patch.  I do have some additional test strips in the fader with
> a range of densities.  The 50% patch, however, seems to be representative of
> the midtones, and the black patch is a separate ink.  In the past I've
> tested the black inks, and the MIS and Epson versions are roughly equal and
> very good -- being basically carbon (not the PKN).  A BO print is about as
> good as it gets in this respect, which is one reason Clayton and some others
> are such fans of that approach.
> 
> 
> Paul
> www.PaulRoark.com
> 
> 
> 
> 
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