Why Is My Filament Stringing?
What Is Stringing?
Stringing (also called oozing, hairy prints, or cobwebbing) is when thin strands of plastic appear between different parts of your print. These strings form when the nozzle travels over empty space and small amounts of filament leak out.
While some materials are more prone to stringing than others, it can usually be eliminated or minimized with proper settings adjustments.
Common Causes
1. Temperature Too High
When filament is heated above optimal temperature, it becomes more fluid and oozes easily from the nozzle during travel moves.
Likelihood: Very Common
2. Insufficient Retraction
Retraction pulls filament back into the nozzle to prevent oozing. If distance or speed is too low, filament continues to leak.
Likelihood: Very Common
3. Wet Filament
Moisture in filament turns to steam when heated, creating pressure that forces material out of the nozzle even during retraction.
Likelihood: Common
4. Slow Travel Speed
Slow travel gives more time for filament to ooze. Faster travel moves reduce string formation.
Likelihood: Less Common
Step-by-Step Solutions
Step 1: Reduce Temperature
This is the most effective fix for stringing.
- Lower nozzle temperature by 5°C
- Print a test piece
- Continue reducing by 5°C increments until stringing improves
- Stop if you see under-extrusion or poor layer adhesion
Step 2: Increase Retraction Distance
Retraction pulls filament back to prevent oozing.
- Direct Drive: Increase retraction distance by 0.2-0.5mm (start at 0.8mm, try up to 1.5mm)
- Bowden: Increase retraction distance by 0.5-1mm (start at 5mm, try up to 7mm)
- Don't exceed 2mm on direct drive or 8mm on bowden to avoid clogs
Step 3: Adjust Retraction Speed
- Increase retraction speed to 40-50 mm/s (direct drive) or 50-60 mm/s (bowden)
- Faster retraction pulls filament back more effectively
Step 4: Enable Z-Hop
Z-hop lifts the nozzle during travel moves, reducing contact with printed parts.
- Enable Z-hop in your slicer
- Set Z-hop height to 0.2-0.4mm
- Helps break strings even if they form
Step 5: Dry Your Filament
Wet filament is a major cause of stringing, especially with PETG and TPU.
- Dry filament according to material specifications
- PLA: 50°C for 4-6 hours
- PETG: 65°C for 4-6 hours
- Signs of wet filament: popping sounds, excessive stringing, rough surface
Step 6: Increase Travel Speed
- Increase travel speed to 150-200 mm/s
- Faster travel gives less time for oozing
- Most modern printers can handle high travel speeds safely
Step 7: Enable Coasting (Advanced)
- Coasting stops extrusion slightly before the end of a line
- Reduces pressure in the nozzle
- Use with caution as it can cause under-extrusion
Material-Specific Tips
PLA
- Reduce temperature to 195-205°C
- PLA strings less than most materials
- Usually fixed by temperature alone
PETG
- PETG naturally strings more
- Dry thoroughly before printing
- Reduce temp by 5-10°C from starting point
- Expect some minor stringing
TPU
- TPU strings significantly
- Drying is critical
- Use minimal retraction (0.5-1mm direct drive)
- Some stringing is unavoidable
ABS
- ABS has moderate stringing
- Temperature adjustment usually sufficient
- Ensure filament is dry
Quick Settings Reference
| Setting | To Reduce Stringing |
|---|---|
| Nozzle Temperature | Decrease by 5-10°C |
| Retraction Distance | Increase by 0.5-1mm |
| Retraction Speed | Increase to 40-60 mm/s |
| Travel Speed | Increase to 150-200 mm/s |
| Z-Hop | Enable (0.2-0.4mm) |
| Filament Condition | Dry thoroughly |
When Some Stringing Is Acceptable
It's important to know that:
- Minor stringing on PETG and TPU is normal
- Strings can be removed with a heat gun or lighter
- Perfect prints without any strings may not be achievable with all materials
- Focus on functional quality over aesthetic perfection for internal parts