PETG Stringing: Complete Fix Guide with Test Models

You switch from PLA to PETG for the first time, slice your model with the same settings, and pull a hairy cobweb nightmare off the build plate. Congratulations-you've just met PETG stringing, the single most common frustration with this otherwise excellent material.

The good news: stringing is fixable. The bad news: there's no single magic number. PETG stringing depends on your specific hotend, filament brand, retraction type (Bowden vs direct drive), and even ambient humidity. But I've developed a systematic tuning process that gets 90% of setups to clean prints in under an hour of test printing. Here's the method.

Why PETG Strings More Than PLA

PETG has a wider melting range and higher viscosity than PLA. Where PLA transitions sharply from solid to liquid, PETG stays in a gooey, honey-like state across a broader temperature window. When the nozzle travels between print sections, that gooey filament stretches into thin strings rather than breaking cleanly.

The three variables that control stringing are retraction (pulling filament back from the nozzle tip), temperature (lower = less ooze), and travel speed (faster moves = less time for ooze to form). Dialing in all three gets you clean results.

Step 1: Print a Stringing Test Model

Don't waste time tuning on your actual model. Download a dedicated stringing test-two thin towers spaced 20-30 mm apart. Each print takes 5-8 minutes and gives you a clear pass/fail result. My go-to is the classic two-pillar retraction test, but any model with multiple separated thin features works.

Print the test at your current settings first. This is your baseline. Take a photo. Then change one variable at a time and reprint. Comparing results side by side is the fastest way to zero in on the right values.

Step 2: Retraction Settings

Retraction is your primary weapon against stringing. Here are the starting points by extruder type:

Start at the lower end of retraction distance and increase by 0.5 mm increments until stringing stops. Going too high causes clogs-the filament retracts past the melt zone and jams when it tries to re-enter. If you're past 2.5 mm on direct drive or 7 mm on Bowden without improvement, retraction isn't your problem. Move to temperature.

Step 3: Temperature Tuning

Print a temperature tower from 250°C down to 220°C in 5-degree steps. PETG typically strings least at the lower end of its printable range. Most brands print well at 230-240°C, but some run cleaner as low as 225°C.

Look at each temperature section for two things: stringing (should decrease as temp drops) and layer adhesion (should stay strong). When you find a temperature where stringing is minimal but layers still bond solidly, that's your sweet spot. For most PETG brands, it's somewhere between 225-235°C.

Step 4: Travel Speed and Wipe Settings

Higher travel speed gives ooze less time to form strings. Bump your travel speed to 150-200 mm/s if your printer can handle it. Most modern printers with linear rails or CoreXY kinematics handle 200 mm/s travel moves without issues.

Also enable wipe on retraction in your slicer (called "wipe while retracting" in Cura and PrusaSlicer). This moves the nozzle along the perimeter while retracting, wiping excess filament on the print surface rather than dragging it through the air.

Step 5: Advanced Fixes

If steps 1-4 haven't fully solved your stringing, try these:

• Pressure advance / linear advance: If your printer runs Klipper or has Marlin LA enabled, tuning pressure advance specifically for PETG makes a significant difference. Start at 0.04-0.06 and tune with a test pattern.
• Coasting: This setting stops extrusion slightly before the end of each path, using residual pressure to finish the line. Set coasting distance to 0.1-0.2 mm. It reduces the amount of molten filament in the nozzle at retraction.
• Nozzle cleaning: A worn or dirty nozzle with filament buildup on the tip will string more. Clean or replace your nozzle. Hardened steel nozzles tend to string less than brass due to lower thermal conductivity.

Quick Reference: The Anti-Stringing Checklist

1. Dry your PETG (65°C, 4-6 hours)
2. Set retraction: 1.0 mm direct drive / 5.0 mm Bowden at 30 mm/s
3. Lower temperature to 225-235°C range
4. Increase travel speed to 150-200 mm/s
5. Enable wipe on retraction
6. Enable combing within infill
7. Tune pressure advance if available
8. Clean or replace nozzle