And while most things are equal between these two, the IGFS has an added disadvantage of the yellows fading 'prematurely'. Or is that purely a function of the epson inks, and will thus be the same with Canson baryta photographique. Canson is apparently minimally warmer.
Do I understand you correctly.
Frank
Oops, I made a mistake and got the megalux hour rating jumbled with the years of display prediction when talking about it in the discussion. I have now corrected that section in my earlier post, so that it now reads correctly. I had written: "The limiting factor at
12 Mlux hours for the EEF is loss of the media's pristine cool-white appearance due to yellowing of the coating.
By 25Mlux hours... The sentence should have read: The limiting factor at
25 Mlux hours for the EEF is loss of the media's pristine cool-white appearance due to yellowing of the coating.
By 50Mlux hours... This is probably what confused you. My bad.
As far as the inks go, the yellow is the most fade prone pigment in the Epson UC K3 ink set essentially on every media, but it fades faster on some media than others. The EEF coating chemistry is actually very compatible with the K3 ink (one reason that EEF gets such a high score in the WIR testing methodology). Also, the rapid OBA burnout in EEF which imparts a yellowish shift to the media color tends to offset the tendency of highlight skin tones,etc. to shift towards blue as the yellow pigment fades, but the Aardenburg testing methodology nevertheless correctly flags the OBA burnout in the EEF as more of a problem in the early stages of aging, hence the lower overall rating for EEF compared to other papers like CIPB and IFGS.
To elaborate further, The EEF's OBA burnout issue is what triggers the lower limit at 25 Mlux hours, but by 50mlux hours the media color is now further yellowed and may be more easily noticed depending on the image content, and the yellow ink has now faded enough that the yellowing of the media is no longer compensating the yellow pigment fade as it did in the earlier stages of aging. Think of this system behavior as two distinct failure mechanisms where they initially offset each other visually but eventually all the color blends finally shift enough to trigger the upper Aardenburg visual limit at 50 megalux hours accumulated exposure. BTW, the lower Aardenburg limit tracks the performance of the worst 10 percent of the color patches, while the upper limit tracks the fading of all the color patches on average. The rationale for this is that the observation of fading is also image content dependent. Not all prints use the same color pigments equally, so a print with dominant areas of poorer performing color blends is going to be noticed before one that has dominant colors comprised of more stable color blends. The superior light fade resistance of Epson ABW mode printing compared to full color print mode is a classic example of the impact of the image content, i.e., what colors and tones are present, on the viewer's perception of fading.
The CIPB and the IGFS have much less OBA in the coating layer compared to EEF and thus less OBA burnout than the EEF. The EEF paper also has an additional paper yellowing problem that goes beyond what can be explained solely by OBA fading. It manifests as a serious problem at higher exposure doses. You can see this additional yellowing phenomenon by looking at the full Aardenburg reports for EEF that have been carried out to over 100 megalux hours of accumulated light exposure. EEF truly doesn't deserve the high score it receives in the WIR testing. IMHO, Epson should pull EEF from the "Signature Worthy" line, but it's understandable why Epson isn't under any customer pressure to do so. Customers love the initial cool bright white appearance of EEF, but the loss of this key property will typically take a decade or more to become apparent at many commonly encountered interior light levels, so EEF hasn't been deployed in the real world enough for customers to become well aware of the issue at this time. A good case for why accelerated laboratory testing is useful.
Because the CIPB ad IGFS don't have the same tendency to yellow as strongly as the EEF the Epson 3880/CIPB or 3880/IGFS combinations remain in better condition than EEF for those first 50 Mlux hours of exposure and won't begin to trigger the Aardenburg fading limits until approximately 60 Mlux hours of accumulated exposure. By 90Mlux hours exposure the fading of the yellow colorant is once again bringing just noticeable changes to the print quality. Continue exposing the UC K3 inks and media further and the fading just keeps getting more pronounced until at even higher exposure doses everyone will easily notice that Epson UC yellow pigment is causing a color balance shift in the purplish-blue direction.
So, to your original question - how long will a print made with UC K3 inks last? It does significantly depend on the media choice and just as important, it depends on one's personal tolerance for paper yellowing and somewhat purplish blue skin tones in particular. And it hugely depends on the customer's choice of display environment!!!!. If a print has strong sentimental value, many consumers will keep astonishingly faded prints on the wall. So, light fastness ratings expressed in years are indeed quite elastic.. tell the customer what he or she wants to hear and under some real world circumstances the claim will probably be entirely valid. However, by expressing the light fade resistance in exposure units (megalux hours) and when the allowable fade is confined only to the period of excellence where fading can be measured with instrumentation but little or no noticeable fading can be yet perceived, then the ratings can become a true "apple-to-apples" comparison. As stringent as the Aardenburg test methodology is compared to other testing methods, the fact that some systems get scores in excess of 100 megalux hours is testimony to the fact that there are some impressive products out there in the market today. One just has to identify them and use them
best,
Mark
