....Now, I'm interested to know where you got all this information about the limitations of WIR's evaluation technology and methods. While Mark M-G has pointed to at least one lacuna in their approach, particularly in respect of OBA fading, I haven't seen any literature raising these other concerns you mention, and given that WIR is a serious commercial/scientific enterprise no doubt charging these corporations (who employ highly qualified scientists able to evaluate its work) good money for its services, I must say I'm somewhat surprised to hear they are decades out of date in what they are doing. I'm not saying it's impossible, I'm just wondering about the likelihood. As well, it's important to recognize that the age of a methodology is not the unique determinant of its on-going usefulness - it depends.
Hi Mark:
Thanks for the detailed response and important points you've raised. This discussion thread is very important and long overdue. I've been out all day and am only now responding (I live in California - Pacific Time), but wanted to provide you with some information on where this testing information is available. I will respond more tomorrow.
For one, a superb article on LuLa,
The Weakest Link, by John Pannozzo, President of ColorByte Software, was published on your site back in 2012. That article covered the testing limitations in great detail. See here:
https://luminous-landscape.com/the-weakest-link/More importantly, testing information is widely available on the WIR site. Unfortunately, most people skip all the critical articles Wilhelm has published over the years and jump right to the final testing reports. That said, I've noticed links to many test reports and key publications have disappeared of late, as it seems they're now being incorporated into WIR's massive tomes
The Wilhelm Analog and Digital Color Print Materials Reference Collection and
The Permanence and Care of Color Photographs, which are available to download.
http://www.wilhelm-research.com/WIR_Reference_Collection/The_Wilhelm_Analog_and_Digital_Color_Print_Materials_Reference_Collection-1971_to_2016_(2016-04-01_v13).pdfHowever, if you read all the footnotes included in WIR test reports, you will discover a lot of crucial information if you're willing to research additional publications. It's just that most people want a simple answer on 'how long a print will last' for a given printer/ink/paper combination. The rest is too technical or of little interest to the average consumer. The footnotes in each test report clearly reference articles explaining the methodology used (densitometry), parameters, endpoints, and how they were determined using psychophysical studies.
It's no secret WIR still uses densitometric analysis to perform permanence testing
for printer and paper manufacturers, not because it's desirable in the age of modern inkjet printing and multiple complex colorants, but simply because of manufacturer
politics. It's a big, hot sticky mess. Since manufacturers still cannot agree on ANSI/ISO standards, Wilhelm has his hands tied and is stuck employing the same method for manufacturer testing he developed for color prints decades ago. The manufacturers simply will not budge.
Note this is
not to say WIR doesn't use colorimetric methods for other day-to-day research; I am solely referring here to how print permanence testing is done on behalf of paper and printer manufacturers as we understand it. If indeed any paper or printer manufacturers have contracted with WIR to have testing done using Aardenburg's I* metric model, I am unaware of that but would be thrilled to learn of it.
To be clear, this is certainly not the fault of Wilhelm in any way, who is a brilliant man with innumerable contributions to the field of print permanence. He has been tireless in advocating manufacturers adopt a single, more modern standard.
Of course you may be aware Mark McCormick-Goodhart of Aardenburg once worked as a subcontractor for Henry Wilhelm, at which time Mark invented the I* metric testing model, which employs colorimetric analysis and was developed in conjunction with Henry. In fact, there are many joint publications written by Mark and Henry detailing the I* metric, also available on the WIR site and elsewhere. And the open source, public beta I* software is freely available on WIR to download and test:
http://www.wilhelm-research.com/istar/index.htmlHowever, if the industry were to switch methodologies, the overall 'years on display' (compared to WIR reports) would drop, alarming consumers. Much education would need to take place. Wilhelm uses a standard of 'easily noticeable fading' based on decades-old consumer focus groups (to determine what constituted objectionable fading), whereas Aardenburg adheres to 'little to no noticeable fading,' much more appropriate for artists, photographers, and printmakers whose eyes are more sensitive to losses in color and contrast than the average consumer.
For most of us, a 25-35% loss of color is simply unacceptable. That's why conservation display ratings based on megalux values (used by Aardenburg) are much more meaningful than simple 'years on display' (used by WIR), as display conditions vary widely.
If you reference the footnotes in WIR reports and read other WIR publications, there are many explanations as to why certain starting
density values were chosen. In fact, when WIR added the additional 0.6 starting density value and retested chromogenic dye prints using Fuji Crystal Archive paper, the estimate for 'years on display' dropped nearly in half. This is because the curve drops off. He used to run the tests with a single 1.0 starting density only. These starting densities have continued to evolve over the years.
And that's another reason why there's so much conflicting information on photo lab websites regarding print longevity values. Some labs still claim their chromogenic prints on FCA paper will last 100 years based on outdated WIR data and the standard 450 lux (at 12 hours per day) display conditions. The marketing hype is all over the place, sans any scientific explanation. It's very frustrating for consumers to sort the wheat from the chaff.
In addition, I've been blessed via conversations I've had with Mark McCormick-Goodhart, as he so generously shared his valuable time with me in explaining the history of print permanence testing. I had reached out to him last year to do research in preparation for a print permanence podcast I did for Breathing Color.
If it were permissible, I would post the PDFs from WIR that show how the testing is done, but that is illegal without explicit permission. Meanwhile, this information is readily available on the WIR site, although it requires a lot of digging.
Here is a direct link to a great Wilhelm article,
How Long Will They Last? An Overview of the Light-Fading Stability of Inkjet Prints And Traditional Color Photographs, that should be of help. In this publication you will find much useful information and a table containing the WIR 'Visually-Weighted Endpoint Criteria Set v3.0,' which shows how much color loss is allowed before the test endpoint is triggered. I think people will be surprised to see this data.
See the column showing the 'Allowed Percentage of Change in Initial Status A Densities of 0.6 and 1.0.' Note the term
density is used throughout, as densitometry is employed as I stated initially.
If you are aware of densitometry standards, then you know the meaning of Status A versus Status M for photographic applications. My point being the fact that Status A is mentioned in the WIR paper, which obviously refers to densitometry.
http://www.wilhelm-research.com/ist/WIR_ISTpaper_2002_02_HW.pdfIt's crucial this information comes to light so people can make more informed decisions, and hopefully lobby manufacturers to adopt a more appropriate testing method, the I* metric.
I hope this helps and I will post more tomorrow. Thanks again.
