Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Jeff Medkeff
<medkeff@g...> wrote:
> JULIO FERNANDEZ wrote:

> > Further to my earlier post I like to quote statements from Mr.
Livick:
> > IF YOU MULTIPLY THOSE FLUORESCENT RATINGS BY .33% IT 
> > WILL REFLECT A MORE ACCURATE RATING FOR DAYLIGHT DISPLAY
CONDITIONS WHEN USING ULTRACHROME
> > TYPE OF INKS."
> 
> Does anyone *really* believe this? This quotation claims you have
to 
> multiply Wilhelm's figures by 0.0033 to get a realistic number. 

There is a lack of care here: the original source states

"FLUORESCENT LIGHTING WILL YIELD RATINGS FOR EPSON'S LATEST
ULTRACHROME INKS THAT ARE APPROXIMATELY 2/3 HIGHER THAN NORMAL
DAYLIGHT RATINGS. IF YOU MULTIPLY THOSE FLUORESCENT RATINGS BY .33%"

This includes at least one error (probably two) - it seems likely, in
the context of the other text on the site and general experience, that
either the "2/3" figure is correct and the final multiplication should
be 60% or the final multiplication should be 33% and the earlier
figure should read "3 times higher than normal".  

Which seems more plausible? 

 Fluo 100 years    
 Sun  60  years  (2/3 of 60 being 40, total 100)

or

 Fluo 100 years    
 Sun  33  years  

If the latter, the original text is ambiguous, to say the least. 

On comparing with Wilhelm: I can easily imagine that it would be very
hard to make a procedure, based on quite delicate measurements, that
would match to within a factor of about 2 without taking great care to
do so (same equipment, matching procedure).  I had originally written
Wilhelm instead of "Fluo" above - but that would have been quite
incorrect.  
If a few paper/ink combinations have a consistent lifetime ratio
between the two methods it would be reasonable to conclude that both
sets of results are meaningful  (if they are inconsistent it is not
possible to be sure which is more useful without additional
evidence).