Nozzle oozing is the slow drip of filament that leaks from the nozzle while it heats up or travels between parts of the print. It leaves blobs at the start of a line and fine strings across open gaps. Per Bambu’s stringing-and-oozing guide, the cause is filament that stays too runny because retraction is too low, the nozzle is too hot, or there is no pressure relief.
Oozing is mostly cosmetic, but it ruins a clean surface and seeds stringing. Work the causes in order and reprint the same test after each change.
Your material sets how runny it gets. PETG oozes the most at print temperature, PLA the least, and any wet filament oozes worse.
Where the fault comes from
| Likely cause | Fix | Severity |
|---|---|---|
| Retraction too low or off | Raise retraction distance a step at a time so the filament pulls back during travel. | hi |
| Nozzle temp too high | Lower the nozzle 5 to 10 C so the filament runs less runny. | hi |
| No pressure advance or coasting | Enable wipe while retracting, or coasting in Cura. | md |
| Wet filament | Dry the spool, then reprint. Wet filament oozes and pops more. | md |
| Idle nozzle too hot before the print | Use a prime or purge line, or lower the standby temperature. | lo |
Start with these fixes
Print a stringing test, two towers with travel between them, then work top to bottom and reprint after each step.
Raise retraction
Add a little retraction distance and reprint, until the travel moves leave no drip.
Lower the nozzle temp
Cut the nozzle 5 to 10 C and reprint, since cooler filament oozes less.
Turn on pressure relief
Enable wipe while retracting in PrusaSlicer or Bambu Studio, or coasting in Cura.
Dry the filament
If the ooze comes with popping or a rough surface, dry the spool and reprint.
Deeper fixes when the quick ones fall short
When retraction and temperature do not end the drip, the heat and the standby settings are the next place to look.
Tune pressure advance
On Klipper or a printer that supports it, adjust pressure advance to ease filament pressure at the seam.
Lower standby temp
Drop the nozzle temperature it holds before the print starts, so less filament melts out at idle.
Add a prime line
Print a prime or purge line at the start so the first real line begins clean.
How your filament matters
PETG oozes the most at print temperature, so it needs more retraction and a cooler nozzle to behave. PLA oozes the least and stays clean when it is dry. Nylon and flexible TPU ooze and string more, and a wet spool makes every material worse, so dry first.
Mistakes that hide the cause
A few common choices trade the drip for a new problem.
Avoiddo not
- Cranking retraction so far the extruder under-extrudes.
- Dropping the temp below the range, which weakens layers.
- Leaving the nozzle at full print temp for long before the print.
- Changing retraction, temp, and coasting in one pass, so the real cause stays hidden.
Key takeaways
- Nozzle oozing drips filament from too little retraction and a hot nozzle.
- Raise retraction and lower the nozzle temp first.
- Turn on pressure relief, then dry the filament.
- PETG oozes most; PLA least when dry.
For the hairs it leaves behind, the stringing guide covers the fine web between moves, and the filament storage guide covers keeping spools dry.
Related guides
Related
More in this area
Cross-reference
Sources & methodology
2 citations · reviewed 2026-07-10- 01Bambu Lab Wiki: Stringing and oozing (retraction, temp, damp filament)accessed 2026-07-09Tier 1
- 02All3DP: Nozzle clogging vs hot-end oozingaccessed 2026-07-09Tier 2