Okay here's a quick pic of what the problem is. It happens in both directions the head travels.
sorry it's grainy had use a high iso but hopefully you can see the issue I'm having.
I have seen this before and I think it has been discussed before.
As far as it can be judged on the image you put here, it looks like the head being idle on the blank parts gathers more ink in that stage or in other words is suffocating on ink flow when it is printing. On an Epson I would say replace the dampers with new ones. On the Z3100 with the ink sieve probably integrated in the head a replacement of the head is the thing to do. One way to check this theory is reducing the print speed by selecting the highest resolution possible for that media. Increasing drying time in a custom media preset would extend that even further. If it gets better it is most likely the ink supply. One Z3100 head = two sieves, pricewise not bad if compared to the replacement of dampers on some Epson models. It was cheap on the Epson 9000 though, 12 Euro a piece if I recall it correctly.
One other possibility, more unlikely: a new slightly overfilled cart for that color loaded just before the job? HP isn't cheap in filling its carts, there's more in it than the official 120 ML to compensate the ink left in the cart which is again little in my experience. Maybe this time they overdid it. Paul Roark emptied Z3100 PK carts to make yet another quad ink set for an Epson and noticed the ink "surplus" too.
Met vriendelijke groeten, Ernst Dinkla
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