Digital BW, The Print

Igor,

>> There is some blotchiness in the print on the right. 

>I'm not 100% sure what you mean...

Look just left of the second block from the top on the photo on the right.
There are some more neutral areas in that photo that do not appear in the
photo on the left.  

>> Is the drawer a wooden one? What else is in the cabinet?

>Pine tree, lacquered about 20 years ago. ...

> >If there is out gassing, the blotchiness of the print on 
>>the right that was in a sleeve might explain the blotchy affect.

>The print on the right was not in that drawer, but in a cupboard,
>inside an acid free plastic (=can hardly be penetrated by gas) sleeve
>with some similar prints. That's probably the reason it was preserved
>that well.

Was the sleeve a zip-lock that could keep out the air?

I don't know what would cause the discoloration, but when the light exposure
seems too little to be the cause, air pollution is the logical next
candidate, I would think.  Some coatings seem to be more susceptible to
discoloration or to promote gas fade more than others, but I don't know of
any testing with pigments that would tell us which coatings are best in this
regard.  My best guess is that Epson UltraSmooth and Premier Art Hot Press
are among the better coatings for longevity.  On the other hand, anecdotal
stories about Photo Rag suggest it may be rather sensitive to air
pollutants, but I don't know if this also means it would promote gas fade of
the pigments.

Paul
www.PaulRoark.com