Very interesting. I was going to begin another thread about my problems until I came across this one. Well, here goes.
I have been using a factory refurbished 2880 since July 2015 (original printer was shipped back from Epson, but arrived in pieces after serious shipper handling problems). The printer had been behaving quite well, printing marvelous digital negatives using piezography inks. As my supply of some inks was getting low, new inks were ordered and received around the beginning of December. The black ink I had been using went by the name "Opaque Photo Black" (PKZ7-WN-110-1, batch #100809) and was to be replaced by a larger bottle, at IJM's suggestion, of "Warm Neutral Shade 1" (PKZ7-WN-220-1, batch #140725). They appear to be the same inks, different batches.
The printer has been maintained according to IJM's "Printer Cleaning and Preventative Maintenance" and Dana's helpful videos: capping station, gentle scrubbing of print head, wiper blade, print head nipple area, flushing of print head, etc, using piezo flush (PF). Whenever cartridge inks were changed, bottle ink solutions were furiously shaken, and once in the cartridges, were more gently shaken and tapped. Flush cartridges replaced ink cartridges when the printer was not in use for more than several days.
Around the time I began to use the newly ordered inks, K(1), C(2.5), and M(4.5), I began to notice banding in the darkest areas of my digital negatives as well as a general lightening. I then started to do multiple Epson head cleaning, printed head flushing (mainly K), nozzle checks (NCs) , etc. When I had good NCs, I sometimes also did the Calibration Mode option on QTR using the inks or (PF). After a some good NCs and QTR Calibration Mode with PF, I would replace the PF cartridges with the ink cartridges.
About the only conclusion I could draw was that there was something wrong with my blacks, probably not the nozzle because of its good PF and Calibration Mode results, but perhaps either the ink or the cartridge. With only one bottle of K ink and several spare K cartridges, I filled the latter and tried them out. One cartridge was a leaker and had to be relieved from duty. The other three, each filled with the same ink, behaved identically after replacing a PF cartridge with 3-4 head cleanings: poor, almost blank, with a few brief dashes in the upper half of the NC.
I'm at a loss. Is there something I've overlooked? Is there something wrong with the bottle of "Warm Neutral Shade 1" black ink?