Epson XP-15000 deflected gray nozzle check: causing microbanding in ABW prints

[pharmacist]

How to solve this problem ? Firstly I thought it was caused by my home-brewed gray ink, but after exchanged the cartridge with original Epson gray ink, the problem still exists. I already tried the soaking method with a piece of paper towel folded and moisturized with my solution, but with no success. In normal colour printing it cannot be seen unless in ABW mode with large area's of the same gray colour you can see a very fine microbanding in that specific area. From a distance it is fortunately invisible but putting your eyes much closer to the paper you can see a very fine pattern of microbanding.

The nozzle check is at first sight perfect but have close look at the gray nozzle check.

 

[The Hat]

The nozzle check is at first sight perfect but have close look at the gray nozzle check.

Using Photoshop it looks perfectly normal to me and so does the rest of the colours..

 

[Ink stained Fingers]

I have seen this microbanding effect as well and reported it years ago on a WF2010W and the P400; there are several vairables contributing to the effect - the amount of the ink spread - how the ink drop widens when it hits the paper/coating surface - this effect is different with different papers - the amount is small but can be demonstrated and seen with a careful look. The effect varies with the drop size - the highest quality setting prints with the smallest drop size - and less ink will spread less and gaps between adjacent lines may become visible. You may test different quality settings to see this effect. And yes - I have seen the effect to a varying degree with different inks - the least with OEM inks. The effect as I saw it is not limited to pigment black , I saw it with cyan and magenta as well. It may be an effect of the actual surface tension of the ink supporting the ink spread as well. And there is my assumption that some ink residue is builing up at the nozzle rim.

What did I do - I was testing inks and the gloss optimizer years ago and saw that the problem got away with OEM inks - dye and Epson or Canon pigment inks, it may not have gone completely but dropped to a level that it was only visible for a crucial inspection. And I stopped using the highest quality setting - it did not deliver any relevant gain in gamut but just was slowing down the printing speed. And I used a cartridge with a cleaner is stubborn cases and printed/wetted several pages just by printing a 'color' sheet with the cleaner cartridge inserted instead for that color.