Why Does PETG String? Common Causes & Easy Fixes
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Why Does PETG String? Common Causes & Easy Fixes
PETG is strong, durable and great for functional 3D prints, but it can be prone to stringing if your temperature, retraction, speed or filament moisture is not dialled in.
PETG stringing is one of the most common issues people run into when printing with PETG filament. The good news is that it is usually easy to improve with a few small setting changes.
In most cases, PETG stringing is caused by printing too hot, wet filament, poor retraction settings, slow travel moves, or using cooling settings better suited to PLA.
Quick Fix Checklist
- Lower nozzle temperature in 5°C steps
- Dry the PETG before printing
- Tune retraction distance and speed
- Increase travel speed
- Reduce unnecessary travel moves
- Use moderate part cooling
Best Starting Point
If your PETG is stringing badly, start by drying the filament and lowering the nozzle temperature slightly. These two changes often make the biggest difference.
1. Your Nozzle Temperature Is Too High
PETG needs more heat than PLA, but printing too hot can cause the filament to ooze from the nozzle during travel moves. This creates fine hairs or strings between parts of the print.
If you are getting stringing, try lowering your nozzle temperature by 5°C at a time until the strings reduce without causing poor layer adhesion.
Most PETG prints well around 230–245°C, but the best temperature depends on your printer, hotend, print speed and filament brand.
2. The PETG Filament Is Wet
PETG can absorb moisture from the air. Wet PETG often causes stringing, popping sounds, rough surfaces, blobs and inconsistent extrusion.
If your PETG used to print well but has started stringing, moisture is one of the first things to check.
PETG Drying Guide
Dry PETG at around 60–70°C for 4–6 hours. After drying, store it in a sealed container or dry box to stop it absorbing moisture again.
3. Retraction Settings Need Tuning
Retraction pulls filament back slightly before the print head travels. If retraction is too low, PETG can ooze from the nozzle and leave strings.
Direct drive printers usually need much lower retraction than Bowden printers. Too much retraction can also cause grinding, clogs or inconsistent extrusion, so tune carefully.
| Printer Type | Starting Retraction Distance | Notes |
|---|---|---|
| Direct Drive | 0.8–2.0mm | Common for Bambu, Prusa direct drive and similar machines |
| Bowden | 3.0–6.0mm | May need more tuning depending on tube length |
4. Travel Speed Is Too Slow
When the nozzle moves slowly between parts of the print, PETG has more time to ooze. Increasing travel speed can help reduce the amount of filament that leaks during travel moves.
You can also enable slicer settings such as avoiding crossing perimeters, combing, or reducing unnecessary travel moves depending on your slicer.
5. Cooling Settings Are Too Aggressive
PETG usually does not need as much cooling as PLA. Too much fan can reduce layer bonding and affect surface quality, while too little cooling can make small details messy.
A good starting point is usually around 20–40% fan, then adjust based on your print quality.
Recommended PETG Starting Settings
| Setting | Recommended Starting Point |
|---|---|
| Nozzle Temperature | 230–245°C |
| Bed Temperature | 70–85°C |
| Fan Speed | 20–40% |
| Retraction | 0.8–2.0mm direct drive |
| Drying | 60–70°C for 4–6 hours |
Final Verdict
PETG stringing is normal, but it is usually fixable. The most important steps are drying the filament, lowering temperature slightly, tuning retraction, and increasing travel speed.
Once PETG is dialled in, it becomes one of the most useful materials for strong, practical and functional 3D prints.
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