Digital BW, The Print

Well that was even better. Excellent. I just wrote out the same thing for a client who using type C material and want's to know the various possibilities. But your version was much better.

 You need to put that statement right on the website.

As to the Neutral K6/7 tests. If I'm not wrong, there is only one sample by one person that was tested on one paper, right? Since then I have submitted two more of the same inks, one on a completely different brand of paper, as well as the HP monochrome samples, Piezo K7 Carbon Sepia etc. But those will take a while to determine. The Selenium K7 set is also in test by someone else.

One thing that seems very certain is that the Piezo Carbon Sepia K7 is a totally beautiful inkset, even effortlessly out of QTR with Jon's curves. I'm starting to use it for my personal work almost completely. It's testing very well. 

j


> 
> Well, apparently I didn't do a very good job explaining it in my first post, so here goes again.
> 
> 18.5 Wilhelm years is about 74 Kodak years! Clear as mud, right? The different "years of display life" predictions come about because Kodak, Wilhelm, Image Engineering, Torrey Pines, IPI, etc. make their predictions by extrapolating the tested light exposure dose to different assumed "average" light levels on display in the real world. For example, Kodak assumes 120 lux for 12 hours per day whereas WIR assumes an average of 450 lux for 12 hours per day. Neither is right and neither is wrong because real world print display conditions run lower than 10 lux all the way up to greater than 5000 lux for 12 hours per day. Pick your own assumed level. It is an enormous range for any lab to be just assuming one "appropriate" value, and it's precisely why AaI&A elects not to assume just one normative level for predicting print life. Better to give the exposure dose in megalux hours and let the end user choose a light level condition for display that fits his/her real world viewing situation.
> 
> This is all classic exposure reciprocity law (i.e. exposure = intensity x time), so if you assume 4x more light on the print, then the fading is assumed to occur 4x faster. Hence, the sample in question would reach fading levels that trigger the AaI&A conservation display limits in 18.5 years if exposed to 450 lux-12 hours/day light exposure doses but it would take 74 years to get to a similar level of fade if displayed at 120 lux-12 hours per day.  And if a museum curator were to specify 50 lux for 12 hours per day, this particular print would "last" up to 167 years on continuous display. Yet, place the print in a a hotel lobby with atrium skylights, and daily light levels could easily reach 2000 lux, so now that same print will "last" about 4 years.  So, that's the light-induced fading impact of various display locations on this 37 megalux hour rated print process.  If this sample had been rated at 74 megalux hours then you get to double all the predictions which would, for example, then  give the hotel lobby location 8 years of display time rather than 4.  The print's real world environment clearly alters the " life prediction" by an enormous amount which is why AaI&A doesn't do the extrapolation for you, we provide the megalux hour ratings and let you make your own assumptions about the light levels at your display location.
> 
> Now, if you noticed I kept putting the word "last" as in "how long will my print last"" in quotes. This is also very important!!!. It is because all of these print life rating schemes have to define some kind of appropriate endpoint of the test. We can fade a print just a little or we can fade it a lot. In each case, the allowable amount of fade also has a large impact on the rating (not as much as assumed light levels, but still huge). The AaI&A conservation display rating deliberately uses a "little or not noticeable" fade criterion which is suitable for fine art, but in so doing, the rating is DEFINITELY NOT describing some catastrophic failure of the image. The AaI&A conservation display rating tells the end user the exposure dose (usually reported as a range rather than a single value) that the print will tolerate and still remain in visually excellent condition. WIR and other test labs use a more liberal consumer tolerance based on easily noticeble fading. This is an appropriate endpoint assumption for consumer ratings since many consumers do tolerate huge amounts of print fading before they attempt to have a copy print made or throw the print away.  Again, the printed image hasn't disappeared into oblivion, but it is noticeably faded, and at a level of fade that, IMHO, would be of serious concern to the discerning print collector.
> 
> Lastly, it's impossible to make a holistic or comprehensive print life prediction. Temperature, humidity, seasonal cycling, handling abuse, air pollution, and light all take their toll on a print, and while we can test for the sensitivity of prints to these various degradation processes and provide highly relevant information, we can't realistically combine the results to form one single, unifying, comprehensive overall rating. But that doesn't mean knowledge about the individual degradation pathways isn't important. For example, when the curators set light levels at 50 lux they are more or less taking the light-induced degradation pathway off the table for this 37 megalux hour rated print. It will probably show signs of age from other deterioration mechanisms before light induces any noticeable problem, but the exact opposite is true if it goes into the hotel lobby location. There, light will indeed be a primary agent of change on this print.
> 
> Ok, the last lastly: (ranting has been a popular theme in this thread!). The conservation display rating for the k6 neutral sample that was tested (and got this thread going) puts this print sample into a category of print processes most curators/photo conservators would call "moderately light fast".  It beats Fuji Crystal Archive paper ,for example, which is a color print processes also considered to have moderate but not high light fastness.  The museum world deals every day with works of art that are much more light sensitive. They  would achieve AaI&A conservation display ratings as low as 0.1 megalux hours, and hence fade significantly in a matter of days in that hotel lobby location! 100 Megalux hours and greater is a rating that I especially like to see, and some of my tested samples have gotten there!  A 100 megalux hour rating pretty much guarantees in all but the brightest display locations that light induced fading probably won't be the determining death factor in the print life equation.
> 
> Now, I should go have that beer with Jon, Tyler, et al!
> 
> cheers,
> 
> Mark
> http://www.aardenburg-imaging.com
>