I agree with Stefan, that it's better to avoid OBA containing papers (I do that myself religiously), but many photographers do believe "neutral" white is best represented with papers that contain a little OBA. Hahnemuhle Photo Rag is an example where the CIELAB b* value of this matt finish paper has been tweaked to zero by incorporating a relatively small amount of OBAs in the paper core. For luster/gloss type "traditional Fiber" papers like CIPB, the b* value is slightly negative typically about -1 or -2 which to many printmakers appears even more "neutral" to their eye under gallery lighting, but I"m personally "calibrated" over years of doing these measurements to trust b* = 0 as in fact dead neutral under 5000K lighting (Solux lamps, for example), and I'm willing to tolerate very slightly warm white such as papers measuring b* = +1, or +2, but that's my personal printmaking preference.
I achieve my sense of a "traditional photographic aesthetic" mainly by printing on Hahnemuhle Photo Rag Pearl which has a b* white point value about 1.0 so some would say a little on the warm white side. However, Photorag Pearl has so many additional desirable properties including amazing light fade resistance and media white point stability with my Canon Lucia EX ink set, that it has become my main "go to" paper. That said, I do understand why so many folks like IGfS or CIPB, and even why some (who don't know or care about the EEF yellowing issue) love such a cool bright white paper like EEF. It has a b* white point value of about -5.5, so quite bluish in appearance compared to other papers like Photorag Pearl.
As far as the UV blocking issue with glazing, I may surprise some of my friends here on LULA who know how much I care about print permanence by disclosing that I'm somewhat of a contrarian in what is considered to be "best archival framing practices". I essentially don't worry about the UV blocking issue. Better to inform the customer about overall light levels on display than to falsely assure him or her that UV block glazing has solved the light fade issue no matter where the print is displayed. It's just plain wrong, but many framing professionals believe that UV is the only radiation that fades artwork. Blue wavelength radiation which you need in the light source for accurate color rendering has more than enough energy per photon to fade artwork, and there's a larger amount of it in natural daylight filtered through window glass. Hence, worryng about UV striking artwork in the typical home environment is better replaced by concern about overall light intensity levels in the location where the artwork is displayed. An inexpensive lux meter (less than $20 for some on Amazon.com) will guide the customer to much safer display illumination levels. And if the artwork is hung where more appropriate illumination levels are achieved, then the UV content issue gets dealt with just fine as well.
I select glazing(s) primarily by laying down various samples over the printed image and pick one that has low impact on media white and highlight colors. Every glazing has some impact on highlight and media white point color, but some combination of glazing and image content are much worse than others. For example, using a full UV block glazing on a print containing OBA will have an obvious impact, but even a full UV block acrylic has a basic yellowish cast to it that will impact any document underneath, including ones that have no OBA content. Regular photo grade framing glass has a lot of iron content in it that imparts an unwelcome greenish tint to some images. Water white glass, both anti-reflection coated and uncoated tend to show the least impact on image color. Standard acrylic is excellent for retaining image color as well, and is light weight, but scratches easily. So, no glazing works ideally in all applications and with all artwork.
Whether any imparted color change is acceptable to the enduser is a matter of personal choice and again somewhat image content dependent. Images with large areas of whites and pastel highlights in them, especially light blues and cyans, are much more sensitive to choice of glazing than images containing only rich bold colors. The primary role of any glazing, IMHO, is to protect the print from air borne pollution, handling grease, and grime, and physical scratches or abrasion. Any of the typical glazing materials will do that.
I would encourage printmakers to build their own "sample kit" of different glazing products on the market, and experiment with how they influence image appearance under different lighting conditions. It's quite an instructive exercise. Frame destination (
http://www.framedestination.com ) has a pretty good selection of different glazing products. You can buy a small piece of each type, and request they label them for you. I'm sure there are many other good suppliers as well, both locally, and on the internet that can help you out, but FrameDestination is a supplier I use routinely with good results. Some smallish size pieces of glazing should not be too expensive for you to build your personal kit and to show friends and/or clients how the glazing choice impacts the color and tonal appearance of the print.
best,
Mark
http://www.aardenburg-imaging.com
