Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "john" <deanwork2003@...> wrote:

> He is saying >406 WR years for the 7880/9880 http://www.wilhelm-research.com/epson/9880.html
> 
> and > 115 WR years for the same paper on the 7800/9800 - http://www.wilhelm-research.com/epson/9800.html
> 
> And >406 WR years on the 7900/9900 - http://www.wilhelm-research.com/epson/7900.html
> 
>  The new Epson inksets are quadrupling bw stability while the color figures are the same?
> 
> john
> 

My guess is that it is just an unintended clerical oversight, and that all three systems should have been posted with the same ABW score. Also, WIR uses a ">" symbol to mean that no endpoint has yet been reached, but the client wants the consumer to know that the test has proceeded far enough to prove the product is as least as good as the preliminary rating figure cited.  The downside of this effort is merely that one shouldn't "finalize" one's opinions of the comparative performance of different products until the testing is fully completed.  AaI&A uses a similar procedure for reporting AaI& conservation Display ratings. A "+" sign in the AaI&A rating means a lower limit boundary has been reached but the upper limit boundary still requires more exposure, and the test is therefore still ongoing. When no value is listed in the AaI&A database column for the Conservation Display rating it means that no limits have been reached. Tests are also ongoing.

 It's pretty clear to me from the precisely identical scores that the WIR display life ratings for the newer 7880/9880 (K3VM inks) and 7900/9900 (HDR inks) systems are repurposed test results from the original tests that were run on the 7800/9800 (K3 inks) systems.  I base my conclusion on the fact that no image permanence tests (not mine or anyone else's) are totally precise. There will always be some experimental variability when testing different samples even from the same batch of materials.  That said,  such repurposing of the test results would arguably be justified by Epson and WIR if the original tests ended on a limit factor that is common to all three ink sets, and if Epson and WIR believe the new ink sets still have that same limiting factor.  WIR does not list what criterion became the failure mode in its test reports, but K3, K3VM, and HDR share yellow, cyan, and the photo gray inks in common. My guess would be the pure yellow loss criterion at the 0.6 density level in the WIR target set is what is causing the failure in the color tests, and probably a color imbalance of the neutral patches in the ABW mode (the only patches that would be tested in the B&W testing). Hence, the three ink sets should receive ostensibly the same score in the WIR testing protocol based on this common limiting factor. It is less likely that we will see identical performance in the AaI&A tests, because the new vivid magenta, orange, and green inks should have at least some influence on the upper limit boundary of the AaI&A conservation display ratings.

Two other points worth noting.  First, "LImiting factors"  are a commonly devised way of designing product performance testing specifications, not only in image permanence testing but in other types of product testing as well.  One of the aspects of print permanence testing that I recognized only recently when developing the AaI&A conservation display ratings, is that a "limiting factor" in performance does not tell the whole story. We need to report a range (in an analogous way that EPA fuel efficiency ratings present both city and highway scores). Some images will show changes at the limiting factor because they have a lot of image area that possess the limiting colors or tones, but other images will have little or none of that limiting color or tone so they  will show less fading until a more generalized level of fade enters the picture.  Hence, the AaI&A conservation display ratings score a range rather than a single value and that range is based on the performance of the worst 10% of the test colors versus the average performance over the whole color set.  Second, please note that the AaI&A conservation display ratings evaluate the exposure dose tolerated by the product for "little or no noticeable" fade which is thus an assessment of "early stage" fading, whereas WIR uses a consumer-oriented criteria set geared towards "easily noticeable" fade and thus report more advanced levels of fade.  Both early stage fading and later stage fading are important because many systems show non linear fading performance.  A product can do well early on and then fade more rapidly later on, and vice versa.  Although AaI&A doesn't have a "consumer display rating" for easily noticeable fade at this time, the AaI&A tests are continued well past the conservation display rated exposure so that members can see for themselves the full nature of the fading as the products become more severely faded. 


regards,

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