Metallic Papers - Image permanence?

[EricLew]

I've been using my strongest google skills but still haven't come up with anything on this. Has there been any testing of metallic papers like the Moab Slickrock series for image permanence?

Or are these papers just assumed to be for non-archival purposes? I just got a moab sample pack and am intrigued to try these papers out.

Eric

[MHMG]

I posted a reply a few minutes ago to your same question on the DPReview printers and printing forum. Had I known your question would also be on LULA, I would have preferred to reply here because I think this forum is a more sophisticated audience for discussing these kinds of questions in more depth.  Anyway, here's a slightly modified version of my reply for LULA readers:

There are two samples of metallic papers in test at Ardenburg Imaging (See ID#s 259 and 260) One of them is IT Supplies Chrome Metallic Luster Inkjet Paper. The other is Proofline Photochrome Pearl (10.5mil / 270gsm) paper. Both were submitted by an AaI&A member who used an Epson Stylus Photo 1400 printer and Quad Tone Rip to generate a black&white print using only the Epson Claria K and LM inks. So, don't be concerned too much about the high level of fade and shift towards brown in these samples. That result is not so much the metallic paper as it is the novel use of Claria Black ink when used to make full tonal scale images. (see also Id#'s 181-184 in the AaI&A database which are also full tonal scale Claria K prints but made on non metallic papers. They exhibit the same fading signature).

Many RC inkjet papers, especially the "new" metallic papers are actually coming from the same manufacturer. They are being rebadged by media resellers, but are in fact the same stuff. These two papers are a case and point. They appear to be essentially the same paper even though sold by different companies. I would bet good money that Moab Slick Rock Metallic is a rebadged metallic paper as well, but nevertheless one needs to test any specific combination of ink and media to truly know the overall light fastness with any real certainty.

Look in particular at the media white point stability graphs in the test reports for these two samples. Here we see two significant spikes in the b* value that are indicative of additional light induced low intensity staining (LILIS). This additional yellowing effect also can be seen visually in the highlight areas of the "before and after" images in the test reports. These target sample reproductions are generated from the colorimetric measurement data thus are as accurate as modern calibrated displays can render. LILIS is an interesting but undesirable phenomenon that I'm only beginning to figure out the how and why of it. It plays havoc with the I* color and Media White point Stability curves, and it occurs when I don't have time to measure the samples immediately after pulling them from the light fade unit. These two samples sat for several weeks in the dark after I had pulled them from the light fade unit at 60 megalux hours and again at the 100 megalux hour exposure interval before I had time to make the updated colorimetric measurements. In other words, to see the LILIS phenomenon, one needs to expose the print sample to light but then give it a rest in the dark (or low intensity illumination only) for an extended interval of time. The subsequent stain shows up as a significant spike in the b* measurement on the graph for the corresponding accumulated exposure dose which is indicative of more yellowing in the print sample, but it can be bleached away again by further exposure to higher light levels. In other words, when I return the sample to the light fade test unit for another round of exposure, the stain can be eliminated once again, and the curve will plot more predictably after the next exposure interval as if that additional stain had never been there. Unfortunately, the stain returns whenever the print is again returned to a dark storage condition as it did after the 100 megalux hour exposure interval, and the longer one waits the more intense it gets. I don't know the stain level limits, however. It is going to take some very targeted studies to figure out all the reciprocity characteristics of the LILIS phenomenon. Anyway, I believe media that exhibit this phenomenon are very problematic and should be avoided for images that contain delicate highlight and mid tone values which are critical to image fidelity and need to be preserved. I hope the industry will eventually pay attention to this problem, but that will only likely happen if there is some general awareness of it which definitely doesn't exist at this time. It's not a commonly known failure mechanism, and it certainly caught me by surprise as well yet I'm now discovering that LILIS is very pervasive in modern media. It's not just inkjet papers. Even Fuji Crystal Archive II paper (a traditional silver gelatin color chromogenic RC paper) exhibits the LILIS problem.

What I can say with reasonable certainty at this time:  The LILIS problem correlates highly with...wait for it... those popularly incorporated OBAs that consumers seem to love so much in their print papers. I have seen no samples of OBA-free papers exhibiting the LILIS phenomenon, but essentially all OBA containing papers I have tested to date exhibit the problem to varying degrees.

cheers,
Mark

http://www.aardenburg-imaging.com

[Colorwave]

What a peculiar phenomenon.  Shall we dub it the yo-yo yellowing effect?

[EricLew]

Thanks Mark - already responded on DPR, but wanted to give you a shoutout here as well. Everything I read about OBAs makes me want to avoid them, and with such fantastic OBA free papers like Museo Silver Rag and Canson Platine, I don't think I'm losing too much by avoiding them. Thanks again for all the great work at Aardenburg - the amount of information you provide is so far beyond Wilhelm that it really puts those guys to shame.

Eric

[Wayne Fox]

Interesting phenomenon.  I guess long term, does this change how much the paper actually yellows, or does it seem to be a short term oddity that can only be introduced by an extended dark storage period, which remedies itself rather quickly once it’s in the light again.

Additionally, wondering if this is more a result of the accelerated process where the print is exposed to extreme light intensities with the added caveat of having to store them in the dark for a while - maybe something that wouldn’t really show up in a normal conditions?

[MHMG]

Interesting phenomenon.  I guess long term, does this change how much the paper actually yellows, or does it seem to be a short term oddity that can only be introduced by an extended dark storage period, which remedies itself rather quickly once it’s in the light again.

Additionally, wondering if this is more a result of the accelerated process where the print is exposed to extreme light intensities with the added caveat of having to store them in the dark for a while - maybe something that wouldn’t really show up in a normal conditions?

Both questions are good ones. My preliminary conclusion is that this phenomenon is not merely an odd laboratory curiosity and that it is going to show up in real world display and storage situations eventually. It can also add enough additional discoloration to definitely be of concern in fine art applications. The average consumer may tolerate a lot of discoloration in a print, but for fine art prints any loss of quality in highlights and mid tones should be of notable concern to the printmaker and print collectors.

I run my accelerated light fade test units at approximately 10-12 kilolux illumination levels, much lower than most commercially available light fade units which are often operated at 70-100 kilolux. Direct sunlight coming through windows and striking a print will easily create a 30-50 Kilolux illumination level and even indirect natural lighting environments in many modern homes and buildings with large picture windows and skylights can easily reach 2000-5000 lux which is not far off 10Klux, hence, the LILIS effect can certainly be induced under real world display conditions not just on laboratory test units. That said, I don't know the full reciprocity characteristics at this time. There is probably a tipping point at which the light induced staining and bleaching reactions will balance one another, but I don't know where that illumination and exposure tipping point is yet.

More research is needed, but again, I'm pretty sure collectors and curators will witness the problem down the road. However, they probably won't know what to attribute it to. The additional yellowing (it will be in addition to the yellowing caused by loss of OBA fluorescence) will probably be blamed on air borne pollution or thermal aging effects which is not what is causing it. My educated guess at this time (again, more research is needed) is that this additional dark storage or low intensity acquired staining from prior exposure to light is related to the degradation components of OBAs as they break down and lose their fluorescence. One piece of supporting evidence for this hypothesis is that none of the OBA free papers I have tested to date show the effect, even those being tested side by side in batches on the same light fade unit and measured at the same time as other OBA containing papers that do exhibit the effect. Control samples that have never been exposed to much light are not exhibiting the same yellowing, hence it's definitely a light induced staining phenomenon.

The only cautionary advice at this time I can give folks who really care about permanence is to avoid this issue entirely by choosing OBA-free media, or if you have to use OBA containing media, try to stay with media that only has it in the paper core and not in the PE layers of RC media or the ink receptor layers.  An example of OBA in paper core only is  Hahnemuhle Photo Rag. It does show some LILIS effect but nowhere near as much as media with higher OBA content. Similarly, Epson Proofing Paper Semimatte is an RC paper with no OBAs in the ink receptor or front side PE layers. It is also exhibiting no LILIS effect so far in testing although it's not very far along in testing yet, but popular papers like Epson Premium Photo Luster or Canon Platinum Pro have a considerable amount of the LILIS effect, and I've seen it occur in less than 30 megalux hours of accumulated exposure on these media to date.  I anticipate that as I study LILIS more, I will begin to detect it just as soon as OBAs start fading which means it probably will happen with less than 10 megalux hours of exposure in some instances. A larger more focused study of the LILIS reciprocity law behavior is in the planning stages at AaI&A.

cheers,
Mark
http://www.aardenburg-imaging.com

[darlingm]

. . .The subsequent stain shows up as a significant spike in the b* measurement on the graph for the corresponding accumulated exposure dose which is indicative of more yellowing in the print sample, but it can be bleached away again by further exposure to higher light levels. In other words, when I return the sample to the light fade test unit for another round of exposure, the stain can be eliminated once again, and the curve will plot more predictably after the next exposure interval as if that additional stain had never been there. Unfortunately, the stain returns whenever the print is again returned to a dark storage condition as it did after the 100 megalux hour exposure interval, and the longer one waits the more intense it gets. I don't know the stain level limits, however. It is going to take some very targeted studies to figure out all the reciprocity characteristics of the LILIS phenomenon. . .

Appreciate all of your tests.  And, I'm very glad I have always recommended OBA-free papers to my clients.

You often referred to a "stain".  I've seen others caution that if OBA's break down unevenly within a single print, it makes the piece look like it was stained in certain spots but not others.  Yet, I haven't been able to find a photo anywhere showing these "stains".  Wondering if you have an image you can share showing this, and if it would be OK for me to use it (for explanation of OBA's only) if I attributed it to you.