Here's the Lab values:
RC
March 1, 2010
L 94.1
a -0.5
b -4.7
October 1, 2010
L 95
a -0.4
b -2.3
Non OBA Cotton
March 1, 2010
L 97.4
a 0
b 2.4
October 1, 2010
L 98.2
a -0.2
b 0.8
Matte
March 1, 2010
L 96
a 0.6
b -4.3
October 1, 2010
L 96.2
a -0.8
b 0.2
Fiberbased with TiO2
March 1, 2010
L 96.1
a 0.8
b -4.8
October 1, 2010
L 96.5
a 0.2
b 4.1
Speculations:
1/Ilford Galerie Smooth Pearl 11RC or FujiFilm Satin RC, at least one of the RC papers with the FBA in the pulp between the RC barriers. HP has similar qualities. The Fujicolor Crystal Archive chromogene paper is an early example of that concept.
2/One of the Canson Arches qualities, Aquarelle most likely. The bleaching could be TiO2 related, that whitener has amazing qualities in other products like tiles and glass coatings, more or less burning contaminations SO2, NO, away when struck by UV light. Probably related to the UV bleaching practiced for inkjet prints that attracted sulfur from the air.
3/Many varieties around, I have few samples. A fresher sheet of Epson EEM than I measured? FBA in the coating. The shift could be a cumulation of: FBA destruction, air pollution on the coating (SO2) and a cheap whitening agent next to the FBA + woodbase degrading. Scandinavia had its share of Icelandic ash and sulfur dioxide this year.
4/Innova IFA29 Fibaprint White Semi_Matt fits the best here. Whether it actually has TiO2? TiO2 isn't the ideal companion of high loads of FBAs. What I also see in some papers with heavy FBA content, this one included, is a white reflectance compensation at the red of the spectrum and little in between. If the FBA fails in time nothing in the middle will compensate the loss of the brightener's bluer spectrum. FujiFilm PhotoGlossy RC, HP Matte Proofing are other examples.
Edit: an addition to this. Pollution of the paper coating has a lot of influence on Spectrometer readings. I have a Fuji Photo Rag sample in the spectral plots of SpectrumViz. I'm quite sure it is actually HM's Photorag but the sample is older and has been stored in the original Fuji sample book. I think the paper covering it has contaminated the Photo Rag surface. It has an uneven yellow discoloration. When measured with an UV capable Spectrometer the yellow contamination will act as a filter on the UV light so the fluorescence is already reduced + the yellow itself adds to spectral reflectance. In shape the spectral plot is very similar to the HM Photorag plot but deviated and I doubt the FBA is actually destroyed, it is more like measuring the paper with an UV-cut Spectrometer. I will remove that sample but for the time being compare the plots i would say.
met vriendelijke groeten, Ernst Dinkla
spectral plots of +100 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm