Digital BW, The Print

Paul-

Thanks for the response on my questions.  I asked them because I too 
am uncomfortable, in principle, with the use of pure color inks in BW 
printing (as with the K3s).  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 and almost within measurement-to-measurement 
error (at least with the i1) and well within print-to-print variation 
(with the 2400 or 4800).  To put it a little differently, this would 
be a density change in a "pure black" on PHP from something like 1.69 
to 1.66 (my conversion is not exact).  So if this were the difference 
between the two ink sets *over the display life* of a print, it 
wouldn't bother me.

The second reason the question arises is that 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," (i.e., what would happen in the first year or two of display) 
or is it estimated performance over 10 or 20 or 50 or 100 years?   If 
the former, I would find this significant, if the latter I probably 
wouldn't.

Incidentally, what are you measuring?  A black patch, a 50% patch, an 
average of all, etc.?

Thanks again,
Walt

   


  

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark" 
<paul.roark@v...> wrote:
>
> Walt,
> 
> > I read your post with the fade figures and had a few questions on
> > interpretation.
> > 
> > You gave hour figures and though there was a difference between 
the
> > two ink sets, the *absolute* amount of fading was quite minimal on
> > the K3, or so it seemed to me.  So I'm wondering what you think 
the
> > significance of this is over real time.
> 
> I think all of the tested inksets are very good and would not have 
serious
> fading in good display conditions for a very long time.  On the 
other hand,
> we also know that in poor display conditions fading can be much 
faster.
> It's not unusual for prints in real world display to get some 
occasional
> direct sun.  Many are still skeptical that inkjet prints are really 
stable
> enough.  So, the more lightfast the better as far as I'm concerned, 
and the
> fact that the blended MIS inks had only 1/3 the fade of the k3 ABW, 
to me,
> is significant. 
> 
> > Also your figures were for unglazed prints (I gather)
> 
> Yes.
> 
> > and I'm
> > wondering about the effect of glazing on both the absolute and the
> > relative figures.  I notice in Wihelm figures that glazing 
provides a
> > protection factor varying from about 1.4 to 1.8, which is a big
> > difference between paper/ink combinations.
> 
> I have no doubt the glazing helps.  I have no information as to 
whether the
> relative rankings would change, but I frankly doubt it.
> 
> 
> > Finally I wonder about the assumption of linearity--that early
> > results will be linearly extended over time.  I expect these are
> > curves.
> 
> All the information I have suggests the non-linearity is mostly at 
the
> beginning of the process.  I doubt there is exact linearity, but 
I'm just
> not going to worry about it for what I do. 
> 
> > I think you also mentioned that any "toning" with the Epson 
controls
> > increases the use of color inks, but I'm not sure this is true, at
> > least for certain colors.  In using an ABW setting of -12 -16 for 
the
> > USFA (which gives a pretty neutral gray), the usage of yellow in 
the
> > 4800 has dropped to about that of the cyan and magenta, which is 
say
> > it is used mostly for cleaning cycles.  The light magenta and 
light
> > cyan levels seem about what they are without tone adjustment.
> 
> I have not tried to quantify how much color is used for various 
settings.
> The "neutral" ABW seemed like a logical one to use for comparative 
testing.
> So, that is what I did.
> 
> I'm not trying to convince anyone that one inkset is better or 
worse than
> another.  I do tests like this for my own purposes.  To the extent 
others
> can glean useful information from them, all the better.  For my 
purposes,
> the test answered the question of whether it was worth my time to 
make a
> dedicated B&W inkset for the 2400.  It is.  So, I'll see what I can 
come up
> with this next year.   
> 
> More, longer, and better testing would, of course, be even more 
helpful, but
> life and resources are just too short to wait for such -- they just 
are not
> going to happen.  So, I try to move forward with the best I can do 
within a
> reasonable time.  
> 
> I think the more of these types of tests we have the better.  Sadly,
> however, it appears some have become too concerned with pressure 
and threats
> of litigation to keep their results on the web.  See
> http://www.livick.com/method/inkjet/pg1.htm   Many probably thought 
Livick's
> rating of a coated UT2 print at 600+ years as off the wall, but 
it's rather
> in the same league with the relative performances I've seen.  The 
third
> party B&W pigments that I've tested -- specifically the MIS UTs and
> Piezotones -- appear to be very lightfast.  
> 
> Paul
> www.PaulRoark.com
>