How to Fix Stringing in 3D Prints
Stringing — those fine wispy hairs strung between parts of a print — is one of the most common and most fixable print-quality problems. Work through these fixes in order, change one thing at a time, and you will clear it up far faster than randomly tweaking settings.
What causes stringing
Stringing happens when molten plastic oozes out of the nozzle during travel moves — when the print head jumps from one spot to another without printing. Two things drive it: pressure left in the nozzle, and plastic that is too runny. The fixes below tackle both, plus the most overlooked cause of all: wet filament.
1. Dry your filament first
This is the fix people skip, and it is the most important one. Moisture absorbed from the air turns to steam in the hotend, sputtering and dragging strings everywhere — no retraction setting can beat wet filament. PETG, TPU, nylon, and even PLA absorb moisture within days of opening. Dry the spool before changing anything else:
- PLA: 45–55 °C for 4–6 hours
- PETG: 60–65 °C for 4–6 hours
- TPU / nylon: 60–70 °C for 6–12 hours
Use a filament dryer or a food dehydrator. If a previously good spool suddenly strings, moisture is almost always the culprit.
2. Lower the nozzle temperature
Plastic that is too hot stays runny and oozes during travel. Drop the nozzle temperature in 5 °C steps and reprint your test. Lower temperatures mean less ooze, but go too far and you lose layer adhesion and risk under-extrusion — so find the lowest temperature that still gives strong, clean layers. A temp tower makes this quick: it prints several temperatures on one model so you can read off the best one.
3. Tune retraction
Retraction pulls filament back into the nozzle before a travel move, relieving pressure so plastic stops flowing. If you still see strings after drying and lowering temperature, adjust retraction:
- Direct-drive extruders: start around 0.5–1.0 mm, increase in 0.2 mm steps.
- Bowden extruders: start around 3–5 mm, increase in 0.5 mm steps.
- Retraction speed: 25–45 mm/s is a good window; faster relieves pressure quicker but can grind soft filament.
Increase retraction distance until strings disappear, then stop — too much retraction causes clogs, grinding, and gaps at the start of each line.
4. Increase travel speed
The faster the nozzle crosses open space, the less time plastic has to ooze. Raising travel speed to 150–200 mm/s often eliminates the last few fine strings without touching anything else. Most printers handle fast travel moves easily since no plastic is being laid down.
5. Enable wipe and z-hop (carefully)
A short "wipe" move at the end of a line drags the nozzle back over printed plastic to clean it off, and combing (avoid crossing outer walls) keeps travel moves over infill where any ooze is hidden. Z-hop lifts the nozzle during travel to stop it dragging through the print — useful, but it can slightly worsen stringing on some setups, so test it rather than assuming it helps.
6. Check for a worn or partly clogged nozzle
A partial clog or a worn brass nozzle disrupts flow control and brings back stringing even with perfect settings. If you have dialed everything in and strings persist, do a cold pull to clear debris or swap in a fresh nozzle.
A quick troubleshooting order
- Dry the filament.
- Lower nozzle temperature 5–10 °C (run a temp tower).
- Increase retraction distance in small steps.
- Raise travel speed.
- Enable wipe / combing; test z-hop.
- Inspect or replace the nozzle.
Change one variable at a time and reprint the test between each. Most stringing clears up by step three — and a surprising amount of it disappears at step one.
