Digital BW, The Print

Peter,

>>>Two years ago a friend made some beautiful neutral 
>>>BW prints for me on his 1280...   I kept them in a drawer.  
>>>Today they are a nice rich shade of green...
> 
>> And I'll bet they were dye prints, not pigments.

>Of course, but the 870 prints ... sitting out under fluorescent 
>lights for same the period of timne look fine.   ...
> What this shows is that there are variables at work here that 
>we don't have any idea about.

My fiber-based silver prints that are in the worst shape are also those that
were in a drawer (file cabinet).  The yellowing of the paper formed a clear
pattern that showed it was gas diffusing in from the edges.  The cabinet in
my case was metal, and the silver prints were not touching any acidic paper.
However, there was cheap paper -- file folders -- in the same cabinet.

So, I'd guess the cause of the accelerated green shift was a gas attack.  If
the drawers are wood, I'd wonder about out-gassing from the wood itself.
(Recall that cedar chests that smell so good are actually putting out a gas
that may be toxic to moths.)  Also, as my experience shows, what else is in
the cabinet is also a potential source of trouble.

In general, it's the acids that attack paper and oxidizers that attack the
image-forming substance.  As with fading, the pigments do much better than
dyes with respect to gas attacks.  It's the same surface area to mass ratio
or the particles or crystals that is usually cited as the reason for this
advantage.

I don't trust dye-formed prints at all and will not use them for any photo
that I want to last for any significant time.

>>You think you know the proprietary ingredients of the photo 
>>paper from the large manufacturers?  

>The basic chemistry of silver halide photography has been well 
>understood by everyone for a century. 

Well, it wasn't known enough to stop people from using toners that didn't
preserve the images the way they were thought to.  

In general, I'd say humanity's knowledge of and experience with papers and
pigments are way older and more extensive than its silver halide knowledge &
experience.  The paper and pigment industries are also much larger than the
photo industry.  Wilhelm is hardly the only source of information.  For
example, pigments have standard ASTM lightfastness ratings.  There are
international standards for archival paper. 

Everything fades and is subject to gas attack.  If the silver-halide prints
had been subject to the same scrutiny as the inkjet print, they might not
have a very good reputation.  The main photographic disaster caused by
fading is the loss of a huge percentage of the early color prints -- the
dyes were very unstable even in the dark.  It is really only the dyes in the
inkjet world that have been the cause of the focus on fading.  If all
inkjets used pigments, I doubt we'd be talking much about image instability
at all.

The main new ingredient in the pigment inkjet world is the coating on the
paper, and I understand why some would not trust these.  They have not stood
the test of time.  It is for this reason that I spent a fair amount of time
to get the UT7 and 2200 to print well on un-coated Arches paper.  With the
UT7, the 2200, and Arches Hot Press, very smooth photographic prints with a
dmax of up to 1.56 are a reality.

However, I note that even Arches had some paper discoloration issues in the
not too distant past.  Additionally, the Epson UltraSmooth (probably the
same coating as Epson Scrapbook and PremierArt Fine Art Hot Press) and even
the Epson Premium Semigloss did better in my initial fade testing.
 
> ... It's a crap shoot.

Life is a crap shoot, but with the exercise of some good judgment it can be
a good bet.

Paul
www.PaulRoark.com