One of my ink channels is completely blank in nozzle check

Printer: Epson p400
Ink: Piezography 2 / PiezoDN

Before starting a print job this morning, I topped off and reset two carts (R and OR) that were nearly empty. I waited an hour and did a head cleaning. A nozzle check had gaps in R and OR, which I expected. There were no gaps in PK (why I mention this will be clear in a moment). I did another head cleaning, then another nozzle check. This nozzle was perfect except for PK, which was completely blank!


I switched off the printer and turned it back on, and did another nozzle check. Same result: PK channel completely blank.

Two questions:

  1. what caused the printer to lose the PK channel? What can I do to fix it?

  2. if I print negatives with PK in its current state, will it harm the printer? (PK contains matte black ink, which is not used on negatives)

Update: I re-seated the PK cartridge and ran another nozzle check. PK now has gaps, but at least the ink is flowing. I’m still wondering what could have caused this, and whether PK is at all relevant when printing negatives.

When a full channel goes on this printer it indicates that an air bubble is working its way through the print channel. Generally another cleaning or two will get rid of this air bubble.


Thanks for the suggestion. I wonder how the bubble got there, unless I disturbed PK when I removed OR (its next-door neighbor). As I mentioned in the update, PK ink is once again flowing. But for now, I’m ignoring PK and printing negatives.

This happens occasionally on my 7900 loaded with Pro inks. I agree that it is likely an air bubble. The worst scenario is that the channel drops out during a print :face_with_raised_eyebrow:.

In any case, though I can’t yet prove it, my sense is that the air bubbles are being introduced when I remove the carts to gently agitate the ink (which I do every few weeks). I think the air bubble may be introduced at the valve which is where the printer ink bay mechanism mates with the cart when it is inserted. In a 7900 it may take some time before the bubble reaches the damper/head because of the length of the supply tubes, so it is really hard to correlate the cart insertion with a later dropout.

@datro it’s a bit different w/ the x900s. These have dampers that collector micro-air from the ink. A cleaning will then get rid of this air but if enough air collects without a cleaning then you get a full channel drop. It’s worth it to do a normal cleaning (regardless of nozzles printing) once a week to get rid of any air that may have collected in the dampers over time. The more you print the more air collects in the dampers. This is the case with any ink (Epson or non-epson).