Fading of patch sheets in the dark

[Ink stained Fingers]

There is another varible you can look to - which color is drifting the most in these 9 months. it is in this case a saturated green which is drifting by a deltaE of 12.59, and such a drift by a saturated color is averaged away by the lighter colors which drift less - there are just less dye molecules which can change over time.

 

[Ink stained Fingers]

Just out of curiosity, have you ever tested the the change of the paper itself?

You would need to differentiate between papers with and w/o coating, the coating should cover up most of the paper related effects. And there is one more culprit - the optical brighteners act like other dye inks - they fade as well - even pretty fast , even faster than some inks . I have shown the effect in various previous postings, as well a spectral display of the paper white before and after exposure. The OBA's in coated papers are embedded in the coating, not in the base paper itself. And there is even a more serious effect - those OBA's don't just disappear but they cause yellow staining over a longer time, Aardenburg has published a document about this effect rarely taken into account.
Some comments here:
https://www.aardenburg-imaging.com/...n-archival-pigment-and-other-fine-art-prints/
https://www.aardenburg-imaging.com/optical-brighteners-obas/

So there are various effects overall overlapping each other and making it a pretty complex job to assess the overall fading performance of a given ink/paper combination. Since these effects are independent of each other simple reciprocal extrapolation of test results is just not possible, I just post the test results and the way how I got them to get some 'feeling' how different inks/papers perform under the tests as posted, I won't convert them in 'mega display hours' or alike, I don't have a lab in which I could do tests with exactly the same environmental conditions. The dark fading test is rather simple in this sense - there is no way to accelerate it - a darker than dark test environment is not possible.

 

[Ink stained Fingers]

Let me update the fading results after 1 year with the patch sheets kept in the dark, but w/o any specific additional archiving precautions e.g. albums with acid free paper, special boxes or whatever. It appears to me that some ink/paper combinations are drifting slower since the last report - 9 months after print. I'm listing here the average of the color shifts of 96 patch fields after 1 hour after print to 1 year and 1 month after print to 1 year. The differences between the Epson OEM 106 ink and the InkTec ink on OEM and 3rd party papers are not very big overall but every ink/paper combination delivers a different result - it is not possible to generalize the findings overall that this or that paper or ink is always better.

I'll keep this test going, but since it is not possible to accelerate a fading test in the dark it'll take a while for more results - probably in a year.