Digital BW, The Print

"John" <jrnolly@...> wrote:
>
> ... most indoor display situations have minimal UV exposure.
> 
> Of a much greater concern is oxidation due to pollutants in the air. Ink jet prints need to be sealed, ...


I've always suspected that was why the Lascaux, which apparently soaks into the coating better, added to the fade test results relative to the UV spray by itself.

I've looked for true oxygen barriers, and there appear to be none that are suitable for our us.  Oxygen gets through all of the transparent barriers we have, including acrylic.  But slowing it down does seem to help.  It's odd that even slowing the air movement around the pigments or dyes seems to help slow the oxidation.  I've wondered if air movement is analogous to blowing on a the embers of a fire.


A fade test result of mine relating to coatings that I found interesting was that in a high humidity test a matte paper that was coated with the polyurethane faded faster than one that was not coated.  I speculate that the water vapor got in through the back and stopped the pigments from being dried out by the lamp.  Whether this would happen in normal display is debatable.  Accelerated testing is often said to exaggerate the longevity of the images because the brighter than normal light dries the pigments, and water/humidity acts as a catalyst for the fading/oxidation.  But, unless the print is encapsulated from both the front and back (perhaps by barrier paper), coatings that are just on one side of the imaging substance might actually have a negative effect.

Paul
www.PaulRoark.com