PETG is a popular 3D printing material offering excellent strength, chemical resistance, and flexibility. However, one common challenge beginners face when printing with PETG is stringing. Fine, unwanted strands of filament can appear between parts, spoiling the final finish. This ultimate guide explains step-by-step how to print PETG without stringing, covering slicer settings, hardware adjustments, and practical printing tips.

1. Understand Why PETG Strings

Stringing occurs when molten filament leaks out of the nozzle during non-print moves. PETG, being slightly stickier and more fluid than materials like PLA, is more prone to this behavior. Factors like excessive heat, insufficient retraction, and moisture absorption contribute significantly to stringing issues during PETG printing.

2. Dry Your PETG Filament Properly

PETG is hygroscopic, meaning it absorbs moisture from the air. Moist filament releases steam when extruded, causing popping sounds, blobs, and increased stringing.

• Dry the filament at 65°C for 4–6 hours in a filament dryer or a modified food dehydrator.
• Store filament in airtight containers with desiccants when not in use.

Keeping your PETG dry ensures smoother extrusion and drastically reduces stringing problems.

3. Optimize Retraction Settings

Proper retraction settings are critical for minimizing PETG stringing.

• Retraction Distance: Start with a retraction distance of 4–6 mm for Bowden setups and 1–2 mm for direct drive systems.
• Retraction Speed: Set retraction speed between 30–45 mm/s. Too fast can cause jams; too slow leaves strings.
• Extra Restart Distance: A slight negative extra restart distance (-0.2 mm) can prevent blobs after retraction.

Testing and fine-tuning these values with small calibration prints leads to significantly cleaner results.

4. Lower the Nozzle Temperature

Printing at higher temperatures makes PETG more fluid, increasing stringing. Finding the lowest effective printing temperature for your filament brand is important.

• Start around 220°C and adjust downward if your prints allow.
• Perform a temperature tower test to identify the optimal temperature where stringing is minimal without causing under-extrusion.

Balancing flow and temperature is essential for clean PETG prints.

5. Enable Wipe and Coasting Features

Advanced slicer features like wipe and coasting help manage filament flow during non-print movements.

• Wipe: Moves the nozzle back over the printed part while retracting, wiping off any extra filament.
• Coasting: Stops extruding slightly before the end of a print move, using residual pressure to complete the extrusion.

Enabling and carefully tuning these settings can eliminate small strings and blobs in PETG prints.

6. Adjust Travel Movements

Fast and smart travel movements minimize stringing by reducing the time the nozzle spends traveling over open spaces.

• Increase Travel Speed: Set travel speeds to at least 150–200 mm/s.
• Enable Combining: Activate “Combing Mode” in your slicer to keep the nozzle within printed areas during travel.
• Avoid Retractions on Travel: Retractions are best reserved for longer non-print moves rather than every small movement.

Optimized travel settings help prevent filament ooze during movement phases.

7. Keep the Nozzle Clean

A dirty nozzle accumulates filament residue, leading to poor extrusion control and more stringing.

• Cold pull technique: Use cold pulls periodically to clean the nozzle internally.
• Brush the nozzle before prints: Use a brass brush to remove any external filament debris.

Maintaining a clean nozzle ensures consistent filament flow and reduces the chance of stringing artifacts.

Common FAQs About Printing PETG Without Stringing

Why does PETG string more than PLA?

PETG has a stickier and more fluid nature when molten, making it more prone to oozing and stringing compared to the stiffer flow characteristics of PLA.

Can drying PETG filament completely stop stringing?

Drying greatly reduces stringing but may not eliminate it entirely. Proper drying, combined with optimized retraction and temperature settings, offers the best results.

Is a direct drive extruder better for printing PETG?

Direct drive extruders generally offer better retraction control than Bowden setups, making them slightly better at managing PETG stringing issues.

Should I always use a cooling fan with PETG?

Moderate cooling (around 30–50 percent fan speed) is recommended for PETG. Too much cooling can cause poor layer adhesion, while too little can contribute to stringing and blobs.

How do I know if stringing is caused by moisture or bad settings?

If your PETG pops or sizzles during extrusion and strings heavily even after adjusting retraction settings, moisture is likely the primary cause.