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Stringing: threads and cobwebs between parts

Severity: MediumAffects: Filament (FDM)Updated July 27, 2026

Symptom

Fine plastic strands are left between two parts of the model, or between two objects on the same plate. Prusa calls it 'hairy prints'. In severe cases the part is covered in a web you have to remove with a knife or heat gun.

Likely causes

In order: the most frequent cause comes first.

  1. 01Damp filament: absorbed water boils inside the nozzle and pushes material out uncontrolled
  2. 02Nozzle temperature too high: the material is runnier and drips under gravity
  3. 03Insufficient retraction distance or speed
  4. 04Low travel speed, which leaves more time to ooze
  5. 05A naturally prone material, such as PETG

How to fix it

Apply one fix at a time and reprint the same test part. Changing three settings at once tells you nothing about which one worked.

  1. 01

    Dry the filament before touching any setting

    Medium

    It is the most frequent cause and the one most people dismiss. Use Prusa's table: PLA at 45 °C for 6 hours, PETG at 55 °C for 6 hours, TPU at 60 °C for 4 to 6 hours, ASA at 80 °C for 4 hours. On the coast and during the rainy season, a spool left open for a week can already be damp.

  2. 02

    Lower the nozzle temperature in five-degree steps

    Medium

    Print a temperature tower and keep the lowest step that still gives good layer adhesion. Every five degrees down visibly reduces oozing. Do not go so low that under-extrusion appears: there is an optimum and the tower shows you where it is.

  3. 03

    Tune retraction for your extruder type

    Medium

    On a direct drive try 0.5 to 2 mm; on a bowden system, 4 to 6 mm, because the filament compresses along the tube. Raise the distance in 0.5 mm steps until the strings disappear, and stop there: retracting too much causes gaps on resume and, with soft materials, clogs.

  4. 04

    Raise travel speed and enable combing

    Easy

    The faster the head crosses the gap, the less string it leaves. Also enable the avoid-crossing-perimeters option — 'combing' — so travel moves happen inside the part and any strings that do form stay hidden.

How to prevent it

  • —Store filament in an airtight box with desiccant, not open on the spool holder
  • —Record the optimum temperature for each brand and colour after running a tower
  • —Revisit retraction whenever you change material, not just colour
  • —With PETG, assume some stringing and place parts apart on the plate

Sources

  1. [1]Stringing and oozing | Prusa Knowledge BasePrusa Research · Manufacturer · accessed July 27, 2026
  2. [2]Drying filament | Prusa Knowledge BasePrusa Research · Manufacturer · accessed July 27, 2026

Related problems

HighFDM

Clogged nozzle: material stops coming out

The extruder turns or makes its characteristic click but no material comes out, or very little and irregularly. Prusa describes a partial clog as the case where the printer pushes some material but not enough, with gaps and incomplete layers, and with the filament curling up instead of coming out straight.

MediumFDM

Blobs and zits: bumps on the surface

Small bumps or zits appear on the walls, almost always aligned vertically at the seam where each layer starts and ends. In severe cases a mass of plastic builds up around the nozzle and can ruin the whole print.

MediumFDM

Overheating: the part deforms on small areas

In areas where each layer is very small — points, thin towers, fine detail — the material looks melted, with rounded edges and a shiny, irregular surface. The geometry is lost and sometimes the part topples.