Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roger" <rsmith02@...> wrote:
>
> This may be a basic question but I recently acquired a pH testing pen
> and have been using it on various papers I have.  My main papers,
> Harmon FB Al and Innova Smooth Cotton 315 both appear to be
> non-acidic.  However the Epson papers I use both look to be quite
> acidic.  
> 
> I am wondering how time will affect these papers.  The tests over at
> Aardenburg of pigment inks on Epson Premium Luster do not indicate
> much change in the paper as a result of decades-equivalent UV exposure
> (loss of UV brighteners but that's about it).  
> 
> What I'm wondering is how will the acids in the paper ultimately
> affect the print?  How concerned should I be with works I've printed
> on Epson semi-gloss or Premium Luster and stored in a dark album or
> behind glass?

Sorry I'm late to the party. This thread has many interesting comments, and I would like to 
jump in at many points. Yahoo's rather non-intuitive threading of comments makes it 
hard for me to know how the conversation has progressed, so let me just tap in here to 
make a few observations.

Accelerated light fade tests are relatively straight forward. While we can argue over 
spectral properties of the light source, reciprocity failure of high intensity short-time 
duration testing, etc., different approaches can give us at least some reasonable insight 
into the sensitivity of various color forming systems to light.  That said, the RC papers like 
Epson Premium Luster have a convoluted problem that is very hard to mimic in 
accelerated tests. The TiO2 whitening layer converts low level light energy to form free 
radicals which do two things. The free radicals oxidize the silver particles in traditional 
silver halide B&W prints, and they embrittle the polyethylene coatings that encapsulate the 
paper core in any RC type print paper. Anti-oxidants have been added which can be 
shown to improve the product significantly, but a sensitive longevity test for these 
materials has still proven to be very illusive.  Traditional thermal aging tests (WIR does run 
these to predict dark stability) can do a pretty good job at predicting thermally induced 
yellowing, staining, and even loss of certain physical properties (which leads to cracking 
and delamination). However,  the light-induced free radical issue in RC papers greatly 
complicates matters, and no good test that could replicate real world anecdotal 
observations about RC paper was ever developed. Thus, RC papers represent a wild card 
in image permanence predictions even to this day. We can test to see that they don't 
discolor and even predict that heat alone won't embrittle them for X number of years, but 
none of this predicts true performance on display where both heat and light interact.

My conclusion: if you want to raise your chances of working with a 300 plus year stable 
substrate, stick with tried and true materials. But that's easier said than done with inkjet 
technology. As others in this thread have noted, this philosophy will constrain us to 
papers that use natural sizings only and have no special image binder layers. Even 
"archival" processed selenium toned silver gelatin prints have a gelatin binder that is 
susceptible to environmental humidity cycling. Photo conservators have already been 
called upon to treat some archivally processed Ansel Adams prints that have cracked 
because they were displayed and stored in seasonally cycled northern winter climates that 
stress the hell out of the gelatin coating (i.e,  by cycling from <20%RH winter to >70% RH 
summer conditions). Gelatin is an amazing polymer. It can tolerate several thousand 
pounds per sq inch of tensile stress (higher than some epoxy glues), but humidity cycling 
can induce these levels, and ultimately after many cycles, microcracks and voids appear, 
then finally large, ugly, highly noticeable cracks.

The whole acid-free issue in photo conservation is another can of worms. Both technicolor 
motion picture film and Kodak Dye transfer prints have proven over time to be much more 
stable than other color imaging systems. Yet both employed approximately 1% acetic acid 
final rinses, so the image layer is without question acidic. Also, consider ordinary news 
paper that has such a bad reputation. Yes, it discolors significantly within days due to the 
light reactive lignin-containing wood pulp, and yes it is an acidic "low stability" paper. Yet 
100 year old examples abound. They are more brittle and they are more discolored 
compared to other papers, but their 
intended function (ie., reading the printed type by holding the paper up to your face) is 
still working just fine.  Had they been stored in more benign environmental conditions, 
they'd be 
even more flexible and less discolored. My point is simply this: Paper pH alone does not 
dictate short-lived paper performance. 

No media can circumvent the laws of thermodynamics. A cynic would say that all art is 
"performance art". We can take steps to make it more stable and less environmentally 
sensitive so that, all other things being equal, it will withstand typical human 
handling,viewing, and storage conditions much better.  Like many of you on this list, I 
work hard in my own personal printmaking to do just that. Also, some artwork ages 
"sympathetically" over time better than others. When the patina of age is not 
objectionable, we often accept it, and even admire it.  
Note the debate which occurred when the Sistine Chapel was restored not too long ago. 
Some experts of antiquity were outraged and felt that the restoration went too far. B&W 
prints often age more sympathetically than color prints. Color prints for the most 
part just get ugly when they fade, but yellowed 19th century albumen prints 
merely enhance our sentimentality about the Victorian Era. 

A good steward of an important work of art on paper is also going to take serious 
steps to manage time on display and to create greatly superior storage conditions. Drop 
the storage temperature about 5 degrees centigrade and most works of art on paper will 
degrade at 
about half their rate compared to the 5C higher temperature environment. Store in cold 
storage, and you will have thousands of years of pristine condition. Cold storage is why 
scientists are discovering nearly fully intact 20,000 year old Woolly mamoth carcasses. 
How long wood the flesh have taken to fully decompose at normal room temperatures? A 
couple of years at best.

I can see that my post is beginning to sound like a rant, but I hope my comments have 
been constructive and will help others to better gage their concerns about acidity, RC 
papers, and the role of environment in image permanence. Despite the more than quarter 
century that I've been involved in image permanence research, I don't consider myself a 
zealot who demands that artists use only the most stable processes. However, I do believe 
that an informed artist is better prepared to make materials and process choices that meet 
his or her needs, and this belief keeps guiding my research.

Best regards,

Mark McCormick
http://www.aardenburg-imaging.com