Stringing (also called oozing or whiskers) is thin plastic strands left between separate islands of a print when the nozzle travels through open air. It wastes cleanup time and can spoil fine details — but you can usually tame it by changing one setting at a time.
What stringing looks like
Fine hairs between towers, posts, or lettering; sticky webs inside hollows; small blobs where travel starts or ends. Heavy bridging sag is a related but different problem — fix bridging after the nozzle stops leaving travel whiskers.
How to identify it
- Print a small dual-tower or stringing test (two pillars with travel between them)
- Photograph against a dark background so thin strands show
- Note whether strands are sparse whiskers or thick ropes (temperature/moisture often thicken them)
- Confirm the first layer is solid first — a bad first layer wastes calibration prints (first-layer calibration guide)
Common causes
- Nozzle too hot — filament stays runny and drips on travel
- Retraction too short or too slow — melt stays in the tip
- Wet filament — steam and soft melt increase ooze (PETG, nylon, and some PLA blends are sensitive)
- Travel behaviour — long travels across gaps, low travel speed, or missing “avoid crossing perimeters” style options
- Material — PETG and flexible filaments string more readily than stiff dry PLA
Troubleshoot simple → advanced
Change one variable per test print. Re-slice, print the same tower, compare photos. If you change temperature and retraction together, you will not know which helped.
- Dry or swap filament — if the spool has been open in humid air, dry per the brand’s guidance or try a fresh dry roll before deep slicer tuning
- Lower nozzle temperature slightly — e.g. 5 °C steps within the manufacturer range (see the filament temperature guide when available)
- Enable / tune retraction — small increases in distance, then speed; stay inside what your extruder can handle without grinding
- Travel and combing — prefer travels that stay inside walls when your slicer offers it; raise travel speed modestly if the machine is stable
- Wipe / coast / extra restart distance — only after temperature and retraction are in a sane band; these are fine-tuning, not first levers
- Hardware checks — PTFE gap (Bowden), worn nozzle, loose extruder grip — after slicer basics fail
Retraction calibration
Direct-drive setups often need shorter retraction than Bowden (illustrative starting bands many people explore: roughly 0.4–1.2 mm direct drive vs a few millimetres on Bowden — verify on your printer). Increase distance in small steps until whiskers drop, then stop before under-extrusion or clicks appear. Then nudge retraction speed upward carefully; too fast can grind filament or skip.
If retraction is already high and stringing remains, temperature or moisture is usually the real culprit — do not keep stacking millimetres.
Temperature testing
Run a temperature tower or reprint the stringing test 5 °C cooler (still inside the spool’s printed range). Cooler often reduces stringing; too cool hurts layer bonding and bridging. Prefer brand TDS ranges over random “PLA is always 200 °C” advice — details live in the temperature guide.
Filament drying and storage
Store spools sealed with desiccant. Dry wet filament in a dryer or low oven only if the manufacturer allows that temperature. Wet PETG can string badly even with “perfect” retraction — drying is not optional troubleshooting theatre.
Material-specific notes
- PLA — often improves with modest temp drop + light retraction; watch cooling
- PETG — strings easily; dry first, then temp, then retraction; may need slower travels
- ABS / ASA — enclosure and stable temps matter; stringing still follows the same order of operations
- TPU — soft filament buckles if retraction is aggressive; favour lower temp, slower travels, and gentle or disabled retraction per your extruder’s guidance
Related tools
Confirm the model is not oversized before you burn filament on tests: STL Viewer & Analyzer. Keep the bed dialled with the first-layer calibration guide so every stringing tower actually sticks. Corners lifting instead of whiskers? See warping troubleshooting.