Ink Oozing after printing

[pathare]

Is it normal that my ink always slowly oozes out? I can pull the plunger completely out and if the tip is pointing down the ink will slowly come out.

[mewertow]

Hey @pathare,

The nozzle will typically leak a small amount once a print has completed, but it's barely enough to be noticeable, and usually stops within a few seconds - for longer prints (40+min) you may see leakage for a minute or so after printing has terminated. If you're seeing that the nozzle is leaking a bunch, or continues to leak for some time after printing has terminated, there are a couple possible causes:

1) Trapped air in the nozzle is the most common cause of leakage. If you recently installed the nozzle, it's common for a small air bubble to be trapped along with the ink. Small air bubbles in the nozzle usually clear within the first few prints.

2) Ink not sufficiently warmed before printing - when the ink warms up, the viscosity will decrease and it will expand a bit. These effects combined lead to increased flow rate and to some leakage if the ink was used when still cold.

3) Ink was over-primed - if you found that you were hitting the '+' a bunch to get a particularly large trace size, then you're likely to see a bit of leakage after printing finishes - if the piston applies an abnormally large amount of pressure on the ink, it will leak as it decompresses, even after the pressure has been released.

[pathare]

I don't feel like any of these fit my problem, I can let the ink come up to room temperature, prime it, and back the plunger all the way off and I still have leakage always. I could just keep wiping away ink from the tip every few seconds. It's not a lot ever but when the printer prints short traces, like pad entries, I get fingers from where the ink never stops flowing when it pulls away.

if the printer prints a longer trace, the build up on the tip when the trace starts isn't a problem anymore and there are no fingers.

[mewertow]

The fingers you're seeing may not be entirely due to ink leakage - when printing very small features, the ink can tend to be drawn upwards a bit by the nozzles. This is because there is not enough ink on the substrate to 'anchor' the ink, so it'll follow the nozzle a bit as it's drawn up.

One approach that can help mitigate these fingers, and helps with printing small features in general, is to try to use a lower print height, for example 0.6-0.8mm.