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.

 

[ptprintfan]

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.

For some reason I never really thought about the relation between the amount of ink and the drift/change of the color, but it makes sense, if what we see is the paper base + ink, the more ink the less the paper base can be seen, if we assume the paper base is much more stable than the ink of course.

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

 

[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.