I can not precisely explain the magenta cast of the Hahnemühle Baryta FB 350 apart from the high OBA content that delivers the blue and the absence of normal whitening agents that should give the paper base a higher reflectance in the green yellow range. There it does not give more than plain bleached cotton fibers create. The higher red reflectance is the thing I wonder about, either the paper base is not that white or something is added to create it. You can check the spectral plot in SpectrumViz: Alpha Cellulose Papers, High Gloss/Glazed There seems to be demand for that paper although most reviewers did not like the paper white at all. Most likely buyers with a taste for an old B&W photo paper with the same paper white. Met vriendelijke groet, Ernst Dinkla Grafische Techniek Quad, piëzografie, giclée www.pigment-print.com On Mon, Jun 24, 2019 at 1:33 PM Roger Breton via colorsync-users < colorsync-users@lists.apple.com> wrote:
Ernst,
This “phenomenon” of some optically brightened paper having a higher a* component is a mystery to me. To your knowledge, is it simply a function of having added a lot of FWA to the substrate, during the manufacturing process? Such that, as more and more FWA is added, a* simply becomes progressively more positive? Turning into “redder” appearance, visually, at some point?
I confess don’t know enough of the behavior of stilbene and other FWA added to inkjet medias, personally, but my hypothesis is that all substrates – inkjets or not – are made up of the SAME FWA, I can’t say whether different FWAs are used, industrially, in the fabrication process? The thought would have never crossed my mind that different FWAs are used for different papers.
I seem to recall that papers with a lower b* value like those used in coated offset papers, like -3.00 or -4.00, rarely get positive a* values? They’re always around 0.50 or 0.60, usually quite low, and hence never appear “reddish”.
I’ll have to check on the Fogra 52 data… (The plot thickens…)
Best / Roger
From: Ernst Dinkla <info@pigment-print.com> Sent: Monday, June 24, 2019 3:32 AM To: graxx@videotron.ca Cc: 'colorsync-users?lists.apple.com' List < colorsync-users@lists.apple.com> Subject: Re: Epson Doubleweight Matte
Roger,
However you will see that effect in the Hahnemühle Baryta FB 350, a magenta cast, that is the result of OBA blue emission + red reflection and little green+yellow contributing to the paper white. Chromatic adaption can not cope with it. Epson Double Weight Matte paper has a similar spectral plot but less pronounced.
Met vriendelijke groet, Ernst
Dinkla Grafische Techniek Quad, piëzografie, giclée www.pigment-print.com <http://www.pigment-print.com>
On Sun, Jun 23, 2019 at 6:48 PM Roger Breton via colorsync-users < colorsync-users@lists.apple.com <mailto:colorsync-users@lists.apple.com>
wrote:
Finally got hold of a fresh sample of Epson Doubleweight Matte paper.
Here is a link to its measurements, in Excel.
https://1drv.ms/x/s!AkD78CVR1NBqkLVN8r7LgHiGqxRYZg
In M1 mode, I believe it's going to be sufficient to carry my humble color separations experiments :
CIE Lab D50/2 (KonicaMinolta FD-7)
93.86
2.53
-8.01
Thank you all for your kind and patient help / Roger
P.S. "Funny", this paper appears to have a slightly "reddish" tint. Of course, it does not appear "reddish" to me, because of chromatic adaptation, no matter what lighting I observe it under.
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