Stringing and oozing — the complete fix list

Those thin spider-web strings between parts on the build plate ("hairy prints") happen when molten filament leaks from the nozzle during travel moves. Six settings cause it; six settings fix it. Work through them in order — the first two solve most cases.

What actually causes stringing

Three physical mechanisms drip plastic during travel moves:

1. Hydrostatic pressure inside the melt zone after a print line ends. The pressure has to be released or it'll push filament out through the nozzle.
2. Steam from moisture trapped in the filament. PLA, PETG, nylon and TPU all absorb water from the air. When water boils inside the hotend it creates micro-bursts of extrusion you can't control.
3. Temperature too high — the plastic is too runny to hold itself in the nozzle against gravity.

Every "fix" below targets one of those three. Knowing which mechanism you're dealing with picks the right fix faster.

1. Dry the filament first (always)

This is the most under-prescribed fix. PLA and PETG that have been on a shelf for a month are usually wet enough to string. Symptoms of wet filament:

• Hissing or popping sounds at the nozzle during extrusion.
• Steam visible at the nozzle in a cool room.
• Rough, bubbly, slightly translucent extrusion lines.
• Stringing that no amount of retraction tuning fixes.

Drying temperatures and times are filament-specific. See the full table in the filament drying guide. Quick reference:

2. Tune retraction

Retraction pulls filament back up the hotend before a travel move to relieve pressure. Distance and speed need to match the printer geometry.

Print a retraction tower (multiple test pillars at increasing retraction distances) to pick the smallest distance that still produces clean travels. More retraction ≠ better — over-retraction can pull cool plastic into the heat break and cause clogs.

3. Lower nozzle temperature

Every 5 °C cooler shrinks string size visibly. Drop until you start to see under-extrusion (gaps in walls, missing layers), then go back up 5 °C.

• PLA: start at 200 °C; try 195 → 190 → 185.
• PETG: start at 230 °C; try 225 → 220 (PETG dislikes going below 220).
• ABS: start at 240 °C; try 235 → 230.
• TPU: start at 225 °C; try 220 → 215.

4. Enable wipe and coast

Slicer features that release pressure without retraction:

• Coasting stops extrusion 0.1–0.4 mm before a line ends. The pressure in the melt zone finishes the line for you. Works best for PETG.
• Wipe on retract drags the nozzle across a printed line as it retracts, leaving the ooze on the part instead of on the travel.
• Avoid crossing perimeters reroutes travel moves so the nozzle stays over infill (where strings are invisible).

5. Speed up travel moves

Faster travels = less time for plastic to ooze. On most modern printers you can safely use:

• Travel speed 250 mm/s (Bambu, CoreXY); 150 mm/s (i3-style bedslingers).
• Travel acceleration 5,000 mm/s² or whatever your printer's input-shaper supports.
• Z-hop on travel — 0.2–0.4 mm lifts the nozzle over printed surfaces so any ooze drops between parts, not onto them.

6. Check hardware

If software tuning doesn't fix it, the hotend itself may be leaking.

• Nozzle not seated against the heat break leaves a gap where melted filament pools and dribbles. Re-tighten the nozzle hot (heat to 250 °C, then snug).
• Worn PTFE tube on Bowden setups lets pressure escape. Replace yearly.
• Heat creep melts filament above the melt zone. See Heat creep.

Material-specific notes

PETG — the worst stringer

PETG strings even when "perfectly" tuned. Best results come from:

• Drying at 65 °C for 6 hours before every long print.
• Combing on, Z-hop off (Z-hop drags PETG strings).
• Retraction 1.5–2.5 mm on direct drive, 5–6 mm on Bowden.
• Coast 0.2 mm.

TPU — flex strings are different

TPU oozes because the filament compresses inside the extruder before pushing through. Solve by lowering retraction speed to 20 mm/s and retraction distance to 0.6 mm. Print slower (25 mm/s) so you don't need much pressure in the melt zone.

Nylon — hygroscopic monster

Nylon absorbs ambient humidity in hours. Print directly from a dryer set to 80 °C. Without that, no setting will produce clean nylon.

Related articles