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Mark McCormick-Goodhart (MHMG), to my knowledge you were the first researcher to identify the LILIS phenomenon; and are still the only one investigating its effects. Between that research and your more general testing of inkjet papers and inks - a targeted testing that is far more relevant to serious photographic artists, IMHO, than the similar work that Wilhelm Institute does - we all owe you a huge round of thanks. I wish the Smithsonian or Library of Congress would support your work with grant monies.
Actually, AFAIK, Henry Wilhelm wrote about this light-induced and light bleachable yellowish stain formation phenomenon (what I call LILIS) in a paper published in an IS&T conference proceedings in 2003. That paper is available on the Wilhelm website
http://www.wilhelm-research.com/ist/WIR_ISTpaper_2003_09_HW.pdfHenry didn't know what caused it, but speculated it might be related to OBAs, and then never published any followup studies that I'm aware of. I was working closely with Henry at the time, and it just didn't come up in our many long and involved print longevity conversations, so I assumed (seriously wrong I should add) that it was a rather obscure issue affecting only a small number of papers on the market at the time. It was only after I was going through many retired samples I now have in the Aardenburg Archives, that I was struck with the reality about how common this problem really is. Why Wilhelm never followed up on it and why the Wilhelm ratings for Epson Premium luster, glossy, and other RC papers are as high as they are is only something he can answer. They don't deserve these good ratings, but IMHO, the entire print permanence research community, myself included, all missed the significance of this problem. It doesn't show up in a typical accelerated light fade testing because the high intensity illumination masks the issue very well by keeping the degraded by-products bleached to a more colorless state, but let the sample go back into a much lower illumination level or a full dark storage condition and the stain rather rapidly reappears. Now that I know what to look for, I'm seeing it in real world examples as well. It's not just a laboratory curiosity.
As for funding for this research, it's definitely a catch 22. No one has a good answer on how this work should best be funded. AaI&A is not elligible for those museum and archive community type of grants, and the classical independent fee-for-service laboratory testing model brings its own set of constraints as well, so AaI&A does not pursue the manufacturers to help support this research. I do the best I can do on a very limited budget.
My question... in advance of the formal conclusions I expect you'll reach at some point with respect to LILIS, can you give us any kind of preliminary hint of which papers seem to avoid or better resist that effect? If you're uncomfortable with that, can you perhaps at least share what your own personal favorite papers are today?
Thanks...
I'm working through a huge "data mining" study at this time involving more measurements on many of the retired test samples to seek out which ones have the LILIS issue and which ones don't. It's slow going, but I"m getting there. One thing is very obvious. The LILIS problem is hugely manifested in the RC photo media. The combination of OBAs incorporated in the TiO2-PE layers accounts for the vast majority of the LILIS problem and it's not pretty! There are some non RC media like ilford Gold Fibre Silk that also display some LILIS effect as well because they also have TiO2 and OBAs in proximity even if they don't have the PE layers. The stain levels are lower. however, so the TiO2-PE layers in RC media seem to be a particularly bad match.
Favorite papers? I primarily use Hahnemuhle Photo Rag Pearl as my main "traditional fiber' photo paper. Beautiful low gloss luster/pearl surface without much distracting bi-directional grain orientation, and it takes protective sprays like Premier Print Shield really well which I use because I hate bronzing and differential gloss. All the glossy/luster type papers exhibit some bronzing with any of the major OEM pigmented ink sets on the market these days. Being a cotton base paper, HN PhRagPearl also has less stiffness that lets me bind it in books in either long or short grain direction although it's probably always better to try to work with the right grain direction when book binding. For RC, I'm using Epson Proofing Paper White SemiMatt because, so far it seems to be largely free of the LILIS effect (but testing is ongoing). There's a positive clue in this result! EpPPWSM does not have any OBA's embedded in the TiO2-PE layers. See the connection?
For fine art matt papers, I use any number of media having little or no OBA. Presently in stock here at AaI&A I have HN Museum Etching and Moab Entrada Natural (because it's a great print-both-sides option at reasonable price and in a wide variety of cut sheet sizes). Most matt media with low OBA content only in the paper core like HN Photo Rag appears to have reasonable whitepoint stability as well. The key there is that the OBAs are not in the coatings, only in the paper base sheet where they seem to remain colorless and not exhibit LILIS after they fade. That's my tentative conclusion at this time.
For folks who really like EEF, there really aren't any dead ringers to substitute for it in terms of both cool-white color and surface texture as well, and to get to a cool white appearance the media will have to have some OBAs. Harman Gloss Baryta has medium OBA content that does fade out over time, but also appears to be free of LILIS, so the yellowing will be confined only to the loss of fluorescence. I think it's a far better outcome than what happens to EEF which is why I don't recommend using EEF. Harman Gloss Baryta, IMHO, also comes closest of all modern inkjet papers to the traditional "F" surface darkroom papers of yesteryear, IMHO, so it appeals to me on that visceral level very much even though I wish Harman would produce a more neutral, i.e. less OBAs, version of this paper. Harman does indeed make a warmtone version, but it's too warm for my taste except possibly for specific B&W images. it's also a very weird paper because it's quite warm yet ironically still has a medium amount of OBAs. I know of no other papers like that. Usually sufficiently warm toned papers are easily made simply by leaving out all OBA.
I hope this helps.
best,
Mark
http://www.aardenburg-imaging.com