Message
Re: Epson Pro3880 with troubled Photo Black ( PK ) for Piezography
2015-03-05 by brian_downunda@...
Richard's point about density loss from overloading is well taken. But it only really applies if you're after *absolute* measurements, such as if you're comparing papers or different ink systems. All I'm really after is a *relative* comparison of the dmax of the various piezography shades 1 on the same paper (HPR since that is what Jon used for his numbers). I want to know whether there's any point to swapping one K7 shade 1 for another, or whether I can use one of them as a universal shade 1. So my numbers implicitly assume that the degree of overloading doesn't change between the various K7 shades 1. I confess that this is an untested assumption.
After a night of drying, my dmax is 1.660 (average of 14 readings). Based on my measurement, WN Opaque 1 is pretty much exactly the same as Selenium 1 (Jon's measurement of 1.661), and as WN 1 is better on gloss I think *it's* the clear choice.
That said, as Jon pointed out on IJM, printing 100% black using a piezography curve combines 4-5 shades with shade 1 making only a minor contribution, so the dmax of shade 1 is not necessarily a guide to the dmax achieved in practice. This makes a universal black even more feasible and sensible. It also means that if you want to do a real world test of alternative systems like K7 and Eb6 you're probably better off printing the 21x4 chart and comparing the density you get in practice, rather than simply comparing the ink separation charts printed in QTR calibration mode.
I hope some of this is of interest to the OP.