Digital BW, The Print

Op 13-1-2011 16:17, Mark schreef:

> I believe there are several factors that influence OBA burnout and
> media white point stability. Here are some of the key variables.
>
> 1) concentration of OBAs, ie.  how much does the initial media color
> depend on the incorporated OBAs. If very little, then total burnout
> produces only slight effect. If a lot, then total burnout produces
> large effect.
>
> 2). Location of OBAs. When located in top microporous coatings, the
> OBAs are extremely sensitive to oxidation (just like other dyes). The
> oxidation can be photochemically induced, but even more so due to
> ozone induced oxidation. The OBA's are more protected when located in
> subbing layers and paper core.  Many RC papers, for example, have
> subbing layers below the top ink receptor layer and above the PE/TiO2
> layer where the manufacturer can include some OBAs.
>
> 3). Molecular structure of the OBA and interaction with the layer(s)
> in which they are embedded. For example, swellable polymers will
> indeed protect them more from oxidation, which in part explains why
> OBAs in traditional darkroom type photo papers have not gotten as bad
> a reputation (although some problems have been experienced in the
> field with traditional photo papers as well).
>
> 4) As a corrollary to item 3), the pore size of the micro/nano porous
> silcates used in the inkjet paper probably plays a role as it can
> also affect the oxygen penetration rates to the OBAs as well as the
> final physical shape of the OBA molecular chain structure due to
> electronic charge influences from the silicates distorting the bonds
> in the dye molecule.
>
> 5) Inclusion of additional tinting pigments in the paper
> size/coatings to achieve cooler media white point thus lessening the
> need for higher OBA concentrations.  Typically you will see lower L*
> values for papers that add some cool-white hue with tinting
> additives, and UV-cut spectral data should still show blue wavelength
> region effects due to the added colorant.
>
> There's undoubtedly other variables as well, but these are some key
> variables that affect OBA fading impact on media white point
> stability.
>
> cheers, Mark http://www.aardenburg-imaging.com

Mark, thank you.

Printed it out  to remind me of all the variables, some I knew, the
other ones about the silicates structure escaped me. For example the HP
Advanced Photo Paper Glossy scored well on keeping its white but has a
micro poreus layer suitable for both dye and pigment inks so I guess
with no additional swellable coating at the top. HP


-- 
Met vriendelijke groeten,   Ernst

Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/

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