Bambu Lab: stringing and oozing between parts of the print and how to remove it in Bambu Studio

Symptom

On a Bambu Lab printer (A1, A1 mini, P1S, P1P, X1, P2S, H2…) thin strings, like cobwebs or hairs, appear between separate areas of the part or between parts on the same plate, or filament oozes during travel and leaves blobs.

Likely causes, from most to least likely

1. Wet filament: the moisture boils as it melts and the filament sputters and oozes. It is the most common cause and retraction alone will not fully fix it.
2. Long travel moves with too little retraction: parts spread far apart on the plate or models with many separate sections.
3. Temperature too high for that filament or for the speed: when printing slowly the filament over-melts and drips.
4. High flow ratio, or a low-density filament such as PLA Aero without its own settings.
5. A worn nozzle, or one with a different diameter from the one chosen when slicing.
6. A worn, loose, too low or broken nozzle wiper: it leaves residue that drags strings.

Checks to tell which one it is

• Try a dry or freshly opened spool: if the strings almost disappear, it was moisture. Crackling sounds or bubbles while printing point the same way.
• In Bambu Studio, check how far apart the parts are on the plate and whether «Avoid crossing wall» is enabled (Process › Quality › Advanced).
• Compare the nozzle temperature with the filament profile and try lowering it by 5-10 °C.
• Check that the nozzle diameter set on the printer and in Bambu Studio matches the nozzle installed, and look for a worn tip.
• Check the nozzle wiper by hand: it must not be broken, loose or lower than the nozzle.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. Dry the filament

   Dry it before printing: in the AMS 2 Pro or AMS HT with their drying function, or on the heated bed of an enclosed printer (X1, P1S, P2S, H2 series) with the spool covered, using the temperature and time in Bambu Lab's table (for example, PETG at 65 °C for 12 h in the AMS 2 Pro). Open-frame printers (A1, A1 mini, A2L, P1P) cannot be used for drying. Then store it in the AMS or a closed box with desiccant.

   Check: When you reprint the same part, the strings are clearly reduced.

   If that does not fix it: Reduce travel moves (next step).

2. Reduce travel moves

   Move the parts closer together on the plate and enable «Avoid crossing wall» in Process › Quality › Advanced, so the nozzle does not cross the outer wall while travelling. With several parts, printing them one by one (Print-by-object, in Special mode) avoids strings between them, keeping the spacing Bambu Studio asks for.

   Check: There are fewer strings between parts and outside the walls.

   If that does not fix it: Adjust retraction.

3. Adjust retraction

   In Printer settings › Extruder (or, for one filament, in its settings › Setting overrides) slightly increase retraction length or speed: Bambu Lab suggests 1.2-1.6 mm at 40-60 mm/s and no more than 2 mm, because a long retraction can clog the nozzle. If strings appear across small gaps, lower the travel distance threshold so it retracts there too. With TPU, be careful: retraction can make it clog.

   Check: Strings disappear or nearly so, without gaps from missing plastic.

   If that does not fix it: Lower the nozzle temperature.

4. Lower the nozzle temperature

   Lower it by 5-10 °C without leaving the filament's range. If you print slowly or have lowered the max volumetric speed, lower it as well: the plastic over-melts and drips.

   Check: There are fewer strings and the layers are still well bonded.

   If that does not fix it: Check the flow ratio.

5. Check the flow ratio and special filaments

   Do not raise the profile's flow ratio: for PETG, Bambu Lab recommends 0.93 to 0.96 (its PETG Basic and PETG-CF default to 0.95). With low-density filaments such as PLA Aero, dry it, lower the temperature and set a flow ratio of 0.5 to 0.7 when slicing.

   Check: The nozzle stops oozing during travel.

   If that does not fix it: Check the nozzle and its wiper.

6. Check the nozzle and its wiper

   If the tip is worn, replace the nozzle, and if the slicer had another diameter, correct it. Repair or replace the nozzle wiper if it is broken, loose or too low. To remove stuck plastic, heat the nozzle first and remove it carefully: it burns.

   Check: The nozzle stays clean and the strings do not come back.

   If that does not fix it: If nothing changes with dry filament and the stock profile, contact Bambu Lab support with photos and the printer logs.

Prevention

• Keep spools in the AMS or a closed box with desiccant; for PETG, Bambu Lab asks for under 20 % humidity.
• Replace the AMS desiccant when its indicator beads change colour.
• Start from the Bambu Studio filament profile and change one setting at a time.

Still not fixed?

Tell usi3d's AI about your case: choose your printer, describe what you see and add photos if you like. It proposes checks step by step, with their sources.

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Printers it applies to

Bambu Lab's FDM printers: A1, A1 mini, A2L, H2C, H2D, H2D Pro, H2S, P1P, P1S, P2S, X1, X1 Carbon, X1E and X2D.

Official sources

This guide summarises the official documentation linked here:

• Stringing and oozing · Bambu Lab
• Retraction · Bambu Lab
• The filament sticks to the nozzle · Bambu Lab
• Filament Drying Recommendations · Bambu Lab
• Bambu Studio advanced quality settings · Bambu Lab
• Print-by-object · Bambu Lab