Digital BW, The Print

On 07/14/2013 05:00 PM, E.Neilsen wrote:

> As to your yellowed edges, the coated papers for ink jet do have issues with
> pH changes and can go a very canary yellow in the wrong pH. In my experience
> it isn't just a slight change in OBAs, but a chemical reaction that is quite
> obvious. It is not even a direct contact issue, but an atmospheric issue
> within a general proximity. Keeping acidic papers, cardboard, cleaners, etc
> anywhere near the prints can put it over the tipping point.
>
> Eric Neilsen

Some papers shift beyond the warm color that can be expected if it had 
no OBAs aboard. The EEF showed that in Aardenburg testing. So there is 
more going on than OBA destruction.

I also think like you do that atmospheric issues can yellow papers with 
and without OBA content. The Entrada Bright White and Red River Aurora 
Bright samples bundled here in the same map with much more matte art 
paper samples showed yellow edges where the other papers didn't. Many 
more papers that stain due to possibly sulphur or nitrogen components in 
the air can be reversed back to a more white reflection with exposure to 
daylight. Which would be odd if it was the OBA being destructed that 
caused the yellowing. I have heard of similar yellowing with matte HM 
papers in Diasec mounting, waiting for the results on my advice to 
expose them to daylight which could be difficult as the front acrylic 
has a UV-cut filtering.

Then there is the odd phenomenon that Mark McCormick described with RC 
papers, after being exposed and then stored in the dark the white gets 
grey and can be reversed to white again with exposure to daylight but 
not totally and not with normal display light power if I recall it 
correctly.


-- 
Met vriendelijke groet, Ernst Dinkla

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012: 500+ inkjet media paper white spectral plots.