Here's something interesting. I've been poking around the silk-screen and t-shirt printing sites because it's something that also interests me. They make positives where we make negatives using similar transparent projection materials. There's a whole line of OHP materials being marketed for either dye or pigmented printers depending on which one you use. The general consensus is that the dye printers do a better job of achieving higher densities. Companies supplying the screen printing industry even market their own line of dye inks for pigmented printers (e.g. R1800 and other Epson models). The REALLY interesting thing about this is that they ADD more UV blocking agents into inks because they need to block at much higher densities 4.0 logD.
Someone out there who needs ink should consider ordering some of these inks to test them out. If they're better for blocking UV they might be just the ticket for making superior digital negatives without having to resort to RIPS. The ArTainium inks in particular seem like they may hold great potential for upping the UV blocking bar.
http://www.imagecreations.ca/html/artainium_ink.html
http://screenprinters.net/product_group.php?gid=fastink&type=fastinkfilm
~m
An interesting article about how inks are designed a couple of paragraphs in.
http://www.primjetcolor.com.pl/inkjet_ink_fading_ns.html#2
So, not only do T-Shirt makers use high UV resistant ink but it's also a desirable trait in the outdoor sign and off-set printing industries.
Does having a high UV resistance (fade resistance) necessarily mean the ink will also block more UV when used in a digital negative?
Historically, how do Epson inks (Dye, Pigmented, K3, Ultrachrome etc.) rank in terms of how well they produce UV density on a negative?
With the printers I have used, it's been my experience that black inks have higher UV densities than visual densities. I don't lnow if that is true with all inks though.I do believe that there's currently a correlation between fade resistance and UV blocking.
Magenta seems to have a great deal of UV blocking power. It's also the color that used to fade the fastest in "old school" inks, but magenta doesn't fade in modern inks, so I'm assuming it's pumped full of UV blockers.
And we had an interesting observation recently from dwross about the UV blocking capabilities of Epson black inks. He noted that they read higher densities on the UV densitometer than they did on the visible light densitometer. This shouldn't happen, because black ink is just carbon particles, and those block everything equally, visible, UV, or IR. So I theorized that Epson has a UV blocker in the liquid binder, so that there's a larger area of paper soaked in UV blocker than just the pigment particles would account for.
Steve,Why do we want higher UV density on the negative? Depending upon process, this does not transalte to higher density on a print. I have just started looking at mark Nelson's PDN, and if my understanding of it is correct, coloured inks are used to reduce the negative density range.
Steve
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