Digital BW, The Print

Just to clarify Paul W's and Paul R's remarks a little further, Batch H completed 120 megalux hours of light exposure, but it's not "complete" in the sense that I still intend to let this batch of samples accumulate much more light exposure over time..The next report update will occur at the end of April, 2013 when the samples will then have reached 140 megalux hours of total exposure.  After that, there will be additional 20 megalux hour intervals until 200 meglalux hours, and after that, if the tests warrant (as I expect Paul's sample will) I will move to 50 megalux hour updates, and we will head towards 300 megalux hours.  At which point I may call it quits on this batch!  It takes about a year to rack up 50 more megalux hours, so we are talking about a very long term ongoing test. 

Some labs use higher light levels and higher UV content to run the tests faster, but there are heat and humidity control issues at the sample plane when doing that, so I'd rather just take more time and collect more precise information along the way.  Also, other labs generally look for one fixed fade point criterion as a means to determine "end of test" and subsequently make a single value prediction of "display lifetime", but that methodology doesn't tell us a lot about how the samples got there or what the nature of the fading looks like visually, and furthermore, a single failure criterion isn't always applicable to all intended uses of the product. For example, fine art prints deserves to be tracked for noticeable fading at levels that would likely trouble curators and conservators but typical consumers might be willing to ignore.  For these reasons, Aardenburg Imaging & Archives provides exposure tabulated data in the test reports that other enterprising souls like Paul R can plot as a fading curve if so inclined. Those curves can tell us whether the system fades linearly or non linearly and what colors and/or tones are deteriorating faster than others with the chosen print process.

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


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Paul Roark <roark.paul@...> wrote:
>
> Paul <paulmwhiting@...> wrote:
> 
> > **
> >
> >
> > ... sample, item #144, and has now logged 120 Megalux-hours. The test was
> > based on Paul Roark's combination of the Epson R1800, 3 cartridges of Eboni
> > ink, Premier Art FineArt paper, and QTR. It continues to do well. ...
> >
> > The Eboni "3-MK" on Premier Art 205 (aka Epson Premier Art Scrapbook
> paper), sprayed with Premier Art Print Shield is doing very well indeed.
>  The 50% patch delta-e is 0.2.  This is way below what would be visible.
>  The http://www.aardenburg-imaging.com/ 120 Mlux-hrs is equivalent to a
> little more than 60 "Wilhelm years" of display.  I look at it as another of
> those "benchmarks" that tell us what the materials, at their best, are
> capable of.
> 
> Paul
> www.PaulRoark.com
> 
> 
> [Non-text portions of this message have been removed]
>