Digital BW, The Print

Paul Roark wrote:

>   If the process
> is oxidation, then even dark stored prints would be expected to "age," 
> even
> if at a rate that is much slower than one exposed to light.
>
> <http://docs.yahoo.com/info/terms/> 

The process GENERALLY (in acid-free papers) is the result of either 
light or gaseous interactions.

Light induced fading can be tested for by placing the print in a vacuum 
and exposing it to light..

Gaseous interactions are generally  either oxidation or the results of 
free-radicals (chlorine, ozone, etc.)..

That's why the "display behind glass" figures are so pointless to me 
except as a baseline for generalized comparisons (like EPA gas mileage 
figures).  The amount of gaseous interaction "behind glass" is so 
reduced from what the average print sees in lits lifetime that it bears 
little relationship to reality...

The sad fact?  Most of these gaseous interaction problems have been long 
known in the dyestuff industry.  As an example, the cyan dye 
disappearance that lays at the heart of the problem with 1270/1280 OEM 
inks has been know as "Gulf Coast Fading" and recognized in the US 
chemical indsutry since 1955..  

The OEM manufacturers tend to develop inks incrementally, changing 
colors bit by bit in each inkset to increase longevity.. The problem 
with the 1270/1280 cyan dye was it had been changed from the previous 6 
color inksets to increase lightfastness.. BUT, EPSON never tested for 
gaseous interactions in general environmental conditions.. They ASSUMED 
that their changes left that part of the inks characteristics 
unchanged... DUMB move!  But, they "needed to get the product out the 
door in conjunction with their standard release cycle."  

AND, as we all know, the real dyes/pigments are not OEM developments... 
they are developed by the Chemical Companies and simply incorporated 
into carriers for the particular printers.  That's part of why I prefer 
dealing with ink/chemical companies for my inks.

[Keith]
 
 




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