Digital BW, The Print

Mike,

keep in mind that 
(a)Paul's results are relative (as he notes), meaning they make sense only 
when compared to each other ,
(b) the overall scale of these recorded changes may be very small in practice 
when results are viewed by the naked eye (remember that the benchmark is 
"before noticeable fading occurs"),
(c) extrapolating data is pure voodoo and everyone - Wilhelm included - is 
trying to do this with good intention, but: We don't know, for example, if we 
were to track changes over time if these inks would "settle" at some point , or if 
their change is rapid at first and slows down to nothing over time... etc.
(d) changes within the tolerance of a densitometer which is likely to be +-0.01 
are hardly meaningful (i.e. you'd need more than 0.02 change to be 
significant) - but because of its logarithmic scale, a densitometer gives you a 
better sense of the visible magnitude of a change.
(e) densitometers (unlike spectrophotometers) are set to read 3 specific 
spectral bands tuned to the photographic dyes used in specific processes 
(E-6, C41 etc). They are not good at reading color in other systems unless the 
spectral peaks of the inks being tested match the photo dyes in one of these 
processes. I would still accept the "visual" reads for black as a good indicator 
of dmax in a print, even though that's fudging a bit too.

In this context, a scanner seems more versatile (as Paul notes, too) but not as 
accurate as a spectro because the data cannot be related to an ICC plot 
without all sorts of color management which introduces a bunch of other 
variables. Nevertheless, Paul's methodology cancels out a lot of scanner 
variables and does show a "relative degree of change" that is real and 
recordable. What to do with it, how to interpret it for our purposes, is the issue 
here. What does 4 days - or 3, or 6 months - predict? 

All this to respond to your notion of "awful lot" !


Antonis

<I'll be back in 100 years with the real results....>


--- In DigitalBlackandWhiteThePrint@y..., "mkravit" <michael.kravit@w...> 
wrote:
> Paul,
> 
> Wow, that seems like an awful lot of fading and color shift compared 
> to the MIS inks.