3D print stringing: causes and fixes.
Stringing means the settings are off. Not slightly off. Wrong in a specific, fixable way. Five adjustments cover 90% of stringing problems. Work through them in order and the threads disappear.
Why your print strings (the real reasons).
When the nozzle moves between two printed areas without extruding, molten plastic can leak out and leave a thin thread. The technical term for that movement is a travel move. Stringing happens when plastic is still fluid enough to ooze during travel.
Some materials stay fluid longer at a given temperature than others. PETG and TPU are more prone to stringing than PLA. This is normal, not a sign something is broken. The fix is the same across materials: pull plastic back before travel (retraction), reduce temp to make it less fluid, and move fast so there is less time to ooze.
The five-step fix that stops 90% of stringing.
Check retraction distance
Retraction pulls plastic back into the nozzle before a travel move. Too little and plastic leaks. Too much and you risk grinding the filament or pulling molten plastic into the cold zone.
Start at the middle of the range. Adjust by 0.5mm increments and test.
Lower print temperature by 5°C
Hotter plastic is more fluid. More fluid means more ooze during travel. Drop temp by 5°C and test. Keep going in 5°C steps until stringing improves or print quality starts to suffer (under-extrusion, weak layer bonds).
Enable combing in your slicer
Combing tells the slicer to route travel moves over already-printed areas instead of open air. Even if some ooze happens, it lands on printed material, not empty space, so no thread forms. In Cura, go to "Travel" settings and set Combing Mode to "Not in Skin" or "All." In PrusaSlicer and Bambu Studio, it is called "Avoid crossing perimeters." This single setting often eliminates most stringing on complex prints without changing any physical parameters.
Increase travel speed
Faster travel means less time for plastic to ooze. This is separate from print speed. A target of 150-200 mm/s travel speed works well for most printers. Faster printers (Bambu, Voron) can go higher. Slower printers (stock Ender 3) should stay at the lower end to avoid frame vibration causing print artifacts.
Dry the filament
Wet filament strings dramatically worse than dry material. If you have tried the four steps above and still have heavy stringing, drying is probably the culprit, especially for PETG, TPU, and Nylon. See our complete filament drying guide for temps, times, and methods.
Why PETG always strings more than PLA.
Test your fix in 20 minutes, not two hours.
Print a stringing torture test. The classic spiked sphere or Cthulhu model from Printables or Thingiverse works well. It has many tall spikes and open space between them, exactly the conditions that reveal stringing. One test print takes 15 to 25 minutes and tells you more than 30 minutes of guessing.
Change one variable per test.
Change ONE setting, print the test, evaluate. Never change two variables at once. If you change temp and retraction at the same time and stringing gets better, you will not know which fix worked, or which one to keep.
If it is wet filament
Stringing that survives correct retraction and a lower nozzle temperature is usually moisture. Two things fix it and keep it fixed.
Filament dryer
Must reach 65C for PETG, 80C if you print nylon
If stringing survives correct retraction and a lower nozzle temperature, the filament is wet. Drying it is the fix, and no slicer setting substitutes for it. Budget units stopping at 55C will not dry PETG properly.
See filament dryer on AmazonAirtight storage with desiccant
Sealed container plus rechargeable silica gel
PETG re-absorbs moisture within a couple of weeks on an open shelf, so a spool you dried last month is wet again. Storage is what makes the fix stick.
See airtight storage with desiccant on AmazonAs an Amazon Associate we earn from qualifying purchases. Links above are affiliate links, and using them costs you nothing extra.
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Fix the next problem.
Write down the settings that fixed it.
The retraction distance that fixed your stringing is worth keeping. Our printable settings guide has the temperature and retraction starting points for every material we document, with room to write in what actually worked. A logging app is in development and we will say so here when it ships.
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