How to Eliminate PETG Stringing: Step-by-Step Diagnostic Guide

PETG print showing stringing before calibration versus clean result after settings tuning

PETG is the most stringing-prone of the common FDM materials because it is highly viscous at print temperature and extremely adhesive to itself. The hairnet of thin strands between towers is the classic symptom, but the fix is almost never a single setting — it is a specific sequence of adjustments applied in order. This guide walks you through that exact sequence.

Root Causes of PETG Stringing

Before adjusting any sliders, understand the three root causes. Fixing the wrong one wastes time and material:

Moisture: Wet PETG boils inside the nozzle and oozes uncontrollably between travel moves. No retraction setting compensates for steam pressure. Dry the spool first, always.
Temperature too high: Every 5°C above the optimal print temp roughly doubles ooze rate in PETG. Nozzle temperature is the single highest-leverage adjustment.
Insufficient retraction: If the filament is not pulled back far enough before a travel move, the molten plug oozes along the travel path and solidifies as a string.

Step-by-Step Fix Sequence

Step 1: Dry Your Filament

Dry at 65°C for 6 hours before attempting any settings changes. Wet PETG looks exactly like a retraction problem but is not fixable with retraction. See our filament drying guide for equipment details.

Step 2: Lower Nozzle Temperature

Print a temperature tower from your current temperature down to 220°C in 5°C steps. Most PETG formulations have their minimum-stringing window between 225–235°C. Drop to the lowest temperature that still shows clean layer bonding and no under-extrusion on bridges.

Step 3: Tune Retraction Distance

Print a retraction test tower (two tall cylinders 50mm apart). Use the starting points in the table below and adjust in 0.2mm increments. Values above 2mm on a direct drive extruder frequently cause clogs.

Extruder Type	Starting Retraction	Max Safe Limit	Retraction Speed
Direct Drive	0.8–1.2 mm	2.0 mm	25–35 mm/s
Bowden (PTFE)	4.0–5.0 mm	7.0 mm	40–50 mm/s

Step 4: Increase Travel Speed

Faster travel moves give the molten nozzle less time to drag a string across a gap. Set travel speed to at least 150 mm/s, ideally 200–250 mm/s if your printer supports it. This is one of the most effective changes for PETG specifically and costs nothing in print quality.

Step 5: Disable Z-Hop

Z-hop pulls the nozzle upward before a travel move, which creates additional ooze time while the Z axis lifts. For PETG, disable Z-hop entirely, or limit it to 0.1mm maximum. Combine with combing to minimize travel paths over open space.

Step 6: Enable Combing Mode

Combing (called "avoid crossing perimeters" in PrusaSlicer) forces all travel moves to stay within the part boundary, so any ooze falls inside the wall cavity instead of across open air.

Slicer-Specific Settings Summary

Setting	Cura	PrusaSlicer / SuperSlicer
Retraction on Layer Change	Enable	Retract on layer change: yes
Wipe Before Retract	Enable (2mm)	Wipe while retracting: yes
Combing	Not in Skin	Avoid crossing perimeters: yes
Z-Hop	Disabled	Lift Z: 0
Pressure Advance	n/a (firmware)	Pressure advance: 0.04–0.08

Tip: Pressure Advance (Klipper) or Linear Advance (Marlin) eliminates ooze at the firmware level. If your printer supports it, a PA value of 0.04–0.08 for PETG often replaces retraction tuning entirely.

Frequently Asked Questions

I dried my PETG and lowered the temp but still have strings. What next?

Run the full retraction test sequence. If you are on a direct drive printer, also check whether your extruder has any play in the filament path — a loose idler arm prevents full retraction even when the distance setting is correct. Tighten the spring tension and retest from step 3.

Does PETG always string more than PLA?

Yes, fundamentally. PETG's higher surface tension and longer melt tail make it more prone to stringing than standard PLA under identical settings. A well-dialed PETG profile will have minimal stringing, but a best-case PETG result will always show slightly more residual stringing than a best-case PLA result on the same printer.

Why does my PETG string only at the start of a new layer?

This is Z-seam ooze, not travel stringing. Enable "Retract on layer change" and set the extra restart distance to a slight negative value (around -0.05mm) to compensate for pressure buildup at layer transitions.

What is a good Pressure Advance value for PETG?

On Klipper, start at 0.05 and run the PA calibration tower. Most direct drive setups settle between 0.04 and 0.08 for PETG. Bowden setups typically require 0.4–0.8. Tuning PA or Linear Advance on Marlin dramatically reduces ooze without the clog risk that high retraction distances carry.