3D Print Stringing: How to Fix It
Stringing (also called oozing or hairing) are the thin plastic threads that appear between separate parts of a print. They're caused by molten filament leaking from the nozzle during travel moves. This guide covers the fix order, retraction settings by printer, and material-specific troubleshooting — including PETG, which strings differently from PLA.
Fix stringing in this order
Work through these steps before touching retraction settings. Most stringing is fixed by step 2.
- Reduce nozzle temperature by 5°C. Hotter filament is more liquid and oozes more during travel. If you're at 215°C for PLA, try 210°C. For PETG at 250°C, try 245°C. Repeat in 5°C steps until stringing improves or print quality degrades (rough surface, gaps).
- Enable combing mode. Combing routes travel moves through the inside of printed walls so the nozzle never crosses open air. This eliminates most visible stringing without touching retraction. In OrcaSlicer: Print Settings → Travel → Travel path → "Within infill". In Cura: "Combing Mode → Within infill".
- Increase travel speed. A faster travel move gives the nozzle less time to drip. Increase travel speed to 150–200 mm/s. This is often more effective than increasing retraction distance.
- Adjust retraction distance. Only after the above steps — increase retraction by 0.2 mm at a time. For direct drive printers: start at 0.5 mm, max ~1.0 mm. Never increase blindly to 2–3 mm on a direct drive — that causes clogs.
- Dry the filament. If stringing is accompanied by popping sounds, a rough surface texture, or bubbles on the print, moisture is the cause. No retraction or temperature change will fix moisture — dry first.
Retraction settings by printer
| Printer | Drive type | Retraction distance | Retraction speed | Notes |
|---|---|---|---|---|
| Bambu Lab P1S / X1C | Direct Drive | 0.4–0.8 mm | 30–45 mm/s | Bambu profiles use 0.8 mm default; reduce to 0.4–0.5 mm for PETG. |
| Bambu Lab A1 / A1 mini | Direct Drive | 0.4–0.8 mm | 30 mm/s | Same as P1 series. Lower temp before increasing retraction. |
| Prusa MK4 | Direct Drive | 0.4–0.6 mm | 45 mm/s | Prusa default is 0.6 mm. PLA works well at 0.4 mm with 215°C. |
| Prusa MK3S+ | Direct Drive | 0.6–0.8 mm | 35 mm/s | Bondtech gears — slightly higher distance than MK4. |
| Creality K1 / K1 Max | Direct Drive | 0.4–0.8 mm | 30 mm/s | High-speed printer — increase travel speed before adding retraction. |
| Creality Ender 3 V3 | Direct Drive | 0.4–0.8 mm | 25 mm/s | Sprite direct extruder. 0.6 mm is a safe starting point. |
| Creality Ender 3 S1 | Direct Drive | 0.4–0.8 mm | 25 mm/s | Same Sprite extruder family. |
| Elegoo Neptune 4 Pro | Direct Drive | 0.6–1.0 mm | 25 mm/s | Start at 0.6 mm; increase by 0.2 mm if strings remain. |
| Anycubic Kobra 3 | Direct Drive | 0.6–1.0 mm | 25 mm/s | — |
Bowden printers (older Ender 3 without direct drive upgrade): use 4–6 mm retraction distance, 40–60 mm/s retraction speed. Bowden tubes add a gap between the extruder and hot end that requires longer retraction to compensate for the slack in the filament path.
Settings by material
| Material | Temp range | Retraction (DD) | Travel speed | Combing | Notes |
|---|---|---|---|---|---|
| PLA | 205–215°C | 0.4–0.8 mm | 150 mm/s | Yes | Easiest to fix — lower temp first. |
| PLA+ | 215–225°C | 0.4–0.8 mm | 150 mm/s | Yes | — |
| PETG | 230–245°C | 0.4–1.0 mm | 150–200 mm/s | Yes | Never exceed 1 mm retraction — causes gaps. Lower temp first. |
| ABS | 240–250°C | 0.6–1.0 mm | 150 mm/s | Yes | Moderate stringing — combing + temp reduction usually solves it. |
| TPU | 220–235°C | 0–0.5 mm | 100 mm/s | Yes | TPU strings heavily. Reduce or disable retraction entirely; use combing. |
PETG stringing: special rules
PETG strings more than PLA even with correct settings because of its higher viscosity at printing temperatures. The key differences:
- Temperature first, retraction second
- PETG stringing is almost always a temperature problem. Reduce nozzle temperature in 5°C steps before touching retraction. At 230°C, PETG strings far less than at 250°C — and layer bonding remains strong.
- Never exceed 1 mm retraction on direct drive
- PETG is prone to under-extrusion after retraction because its semi-viscous nature makes it slow to re-prime the nozzle after a retraction move. If you go above 1 mm, you'll see gaps and rough surfaces. If you've already increased retraction past this point, go back to 0.6 mm and reduce temperature instead.
- Moisture is a major factor
- PETG absorbs moisture more readily than PLA. A spool left out in a humid room for 2–3 days will start to string noticeably. Dry PETG at 65°C for 4–6 hours before long print sessions if stringing has been getting worse over time.
TPU stringing: different rules
TPU (flexible filament) strings heavily due to its elastic nature — the filament stretches inside the tube, and standard retraction pulls it back but then the elastic rebound re-pressurizes the nozzle. The fix is counter-intuitive: reduce retraction or disable it entirely, and rely on combing mode to route travels inside the part. Use low print speeds (20–30 mm/s) so the flexible filament doesn't buckle.
Retraction test: how to calibrate
A retraction tower or stringing test prints two towers with a travel move between them while incrementing retraction distance (or temperature) through the print height. This lets you find the optimal value in a single print rather than through multiple full prints.
In OrcaSlicer: Calibration → Retraction test. In Cura: use the "Retraction Tower" plugin under the Extensions menu. Start the test at 0.2 mm and increment by 0.2 mm per step up to 1.5 mm for direct drive.