Message
Re: Help with RIP
2017-05-11 by sanking@...
What printer are you using, and how did you conclude that the cyan ink is a good UV blocker for Pt/Pd?
I have not tested the cyan with the newer Epson printers (P600, P800, etc.), but with all of the K3 printers the cyan is a very poor UV blocker with alternative printing processes. You can easily verify this by printing an ink separation page with QTR in calibration mode and then using this as a negative to print a pt/pd print, using your standard printing time.
At one time I also believed that the Cyan was a good UV blocker because it does block a lot of UV light with my Gretag D-200 densitometer, and also with the more commonly used X-Rite 361-T. But this appears to be some type of anomaly associated with the narrow band of filters of these densitometers, because when you actually test the cyan with any UV process you will find that cyan it is not a very effective UV blocker. I have found this to be true with all of the Epson K3 printers, all alternative processes I have used, and all llight sources (BL tubes, SA tubess, mercury vapor and metal halide HID lamps, and Continuous Wave Xenon lamps.
I notice that you have used PDN in the past. Perhaps the printing of the color palette in PDN lead you to the conclusion that the cyan is a good UV blocker? If so, please bear in mind that when using the Epson driver there is always some mixing of inks, and the green color that is so popular with this system is actually a mixture of Yellow and Black, along with the Cyan.
My findings are consistent with what many others have reported for UV sensitive alternative processes, but they do not apply to printing with contemporary silver gelatin papers.
Sandy