Dealing with Stringing in PETG: Advanced Techniques

Harry S.

Conquering PETG Stringing

PETG is the most commonly recommended intermediate material for Australian conditions; it is better in heat resistance than PLA, has better UV stability, and is genuinely tough. But it has a notoriety problem: stringing. Compared to PLA, PETG's lower surface tension and higher melt flow at its operating temperature means it oozes more freely during travel moves, producing those characteristic fine threads between model features. For anyone who's spent time fighting PETG stringing, this guide covers the advanced techniques that go beyond the basics of retraction adjustment and temperature reduction.

This guide assumes you've already worked through the fundamental retraction and temperature calibration process covered in our retraction guide and temperature calibration guide. If those haven't resolved your stringing, these more advanced approaches address the remaining causes.

Temperature Gradient Tuning

PETG's stringing behaviour changes dramatically across its temperature range, even more dramatically than PLA. A 10°C temperature reduction often reduces stringing more significantly than any retraction adjustment. The challenge: lower temperatures also risks layer delamination and poor layer bonding. There's a balance point for each PETG formulation where the temperature is low enough to minimise ooze but high enough for full interlayer bonding. Finding it requires systematic testing at 5°C increments. For OzFDM PETG, the typical sweet spot for minimum stringing with good layer bonding is 230–240°C, but the range varies enough between colour formulations that testing is always recommended over assuming.

Wipe Before Retract and Seam Placement

Enabling "Wipe Before Retract" in Cura (or the equivalent in other slicers) moves the nozzle along the outer wall while retraction begins. The nozzle wipes along the wall, mechanically shearing any forming string, then completes the retraction. Combined with fast travel speed, this technique prevents strings from forming rather than relying on suction alone to remove ooze. "Seam placement" also affects stringing: placing all seams (the start/stop point of each perimeter) in a hidden corner or the rear of the model concentrates any string formation to a single, less visible area where it can be cleaned with a heat gun pass.

Z-Hop and Travel Speed

Z-hop (lifting the nozzle by 0.1–0.2mm before travel moves) prevents the nozzle from dragging existing strings across the print surface. However, z-hop also increases the total travel time, meaning the nozzle has more time at elevated temperatures during the lift, move, and lower cycle, which can increase ooze. Test with and without z-hop: for prints with many short travel moves over dense features, z-hop helps; for prints with long travel moves over open space, the speed of travel is usually more important than z-hop. Maximum travel speed (200–250 mm/s) minimises the time the hot nozzle spends in transit, which is ultimately the most reliable strategy for controlling PETG stringing. Quality, consistent diameter PETG filament also helps with diameter variation, which causes irregular ooze that makes stringing less predictable and harder to tune.