Stringing (those thin plastic hairs between parts) and oozing (plastic bleeding from the nozzle during travels) plague most printers at default settings. Both are fixable with the right approach.
Understanding What Causes Stringing
When your nozzle moves from one part to another without extruding, leftover plastic in the hot nozzle oozes out under pressure. This creates thin strings that harden as they cool.
The hotter your nozzle, the worse this gets. The faster you move between points, the less time ooze has to happen. The further apart your features, the longer the string can grow.
The Temperature Path
Temperature is your first lever. Stringing = plastic is too fluid, flowing like honey rather than holding firm.
Test this: Reduce nozzle temperature by 5°C increments until stringing stops. Most materials have a 10-15°C window where quality changes noticeably. For PLA, this might be 205°C vs. 200°C. For PETG, 240°C vs. 235°C.
Common temperature starting points:
- PLA: 190-210°C
- PETG: 230-250°C
- ABS: 240-260°C
If you’re already at the low end and still see stringing, temperature isn’t the culprit.
Retraction Settings: The Core Fix
Retraction pulls filament back into the nozzle before travel moves, removing pressure. After travel, the printer extrudes a tiny bit forward to rebuild pressure—this is called “prime.”
Standard retraction settings:
- Distance: 4-8mm (Bowden), 1-3mm (direct drive)
- Speed: 40-60mm/s
- Z-hop: 0.2-0.5mm (lifts nozzle slightly during travel)
For stringing, increase retraction distance or speed incrementally. More aggressive retraction = less ooze, but excessive retraction causes different problems (tiny blobs at restart points, nozzle wear).
If you’re using Cura: Combing mode matters. “Avoid supports” combs through print interior to avoid exposed travel moves entirely. This eliminates 80% of visible stringing without changing retraction.
Nozzle Size and Print Speed
Smaller nozzles (0.4mm) have less pressure buildup, reducing ooze naturally. Larger nozzles (0.6mm+) suffer more from stringing at equivalent speeds.
Print speed also matters: faster movements leave less time for oozing. Printing at 120mm/s with poor retraction might string visibly, but 60mm/s with the same settings might not. This isn’t fixing the cause—just hiding it.
Line Spacing and Feature Layout
If your model has features far apart, travel moves between them create long opportunities for stringing. Some slicers let you adjust the maximum travel distance before lifting the nozzle (to avoid long exposed strings).
For example, if you’re printing scattered small parts across the bed, grouping them closer (or spacing them very far with Z-hop enabled) reduces visible stringing.
Practical Testing Protocol
Here’s how to actually find your settings instead of guessing:
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Create a test model: Print a simple part with features separated by ~20mm. Repeat the design 5 times with slightly different settings (temperature, retraction distance, or speed).
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Change one variable: If testing temperature, vary it by 5°C between copies. If testing retraction, increase distance by 1mm each copy.
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Print and observe: Look at the travel moves between features. Count visible strings on each copy.
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Lock in the baseline: Once you find settings that eliminate stringing, document them. You now have your material baseline.
Layer Changes and Prime Towers
Prime towers (or prime lines) reestablish nozzle pressure after retracting. A poorly designed prime tower can reintroduce the problem it’s meant to solve.
Ensure prime towers are sized appropriately:
- Too small (2-3mm): insufficient to rebuild pressure
- Too large (8mm+): wastes material and time
When Stringing Persists
If you’ve lowered temperature, increased retraction, and enabled combing—and stringing still appears:
- Check nozzle wear: A scratched or enlarged nozzle can’t hold pressure. Replace if worn.
- Verify Z-offset: Incorrect Z-offset causes inconsistent extrusion, which can mimic stringing.
- Test filament batch: Different manufacturing batches of the same material vary. A dry filament spool eliminates moisture as a variable.
Stringing and oozing are solvable. Start with temperature and retraction, test methodically, and you’ll dial in settings that work for your specific printer and material.