Stringing and Oozing in 3D Prints — Causes & Fixes

Stringing and Oozing in 3D Prints — Causes & Fixes

Those thin spider-web strings between parts on the build plate ("hairy prints") happen when molten filament leaks from the nozzle during travel moves. Six settings cause it; six settings fix it. Work through them in order — the first two solve most cases.

Dry your filament. Wet filament strings no matter what you set. Then drop the nozzle temperature 5 °C and enable wiping plus a small (0.4–0.8 mm extra) retraction. If you're on a Bowden setup, raise retraction distance to 4–6 mm instead. Print a stringing test tower (search "retraction tower STL") and visually pick the cleanest layer.

Three physical mechanisms drip plastic during travel moves:

Every "fix" below targets one of those three. Knowing which mechanism you're dealing with picks the right fix faster.

This is the most under-prescribed fix. PLA and PETG that have been on a shelf for a month are usually wet enough to string. Symptoms of wet filament:

Drying temperatures and times are filament-specific. See the full table in the filament drying guide . Quick reference:

Retraction pulls filament back up the hotend before a travel move to relieve pressure. Distance and speed need to match the printer geometry.

Print a retraction tower (multiple test pillars at increasing retraction distances) to pick the smallest distance that still produces clean travels. More retraction ≠ better — over-retraction can pull cool plastic into the heat break and cause clogs.

Every 5 °C cooler shrinks string size visibly. Drop until you start to see under -extrusion (gaps in walls, missing layers), then go back up 5 °C.

Slicer features that release pressure without retraction:

Faster travels = less time for plastic to ooze. On most modern printers you can safely use:

If software tuning doesn't fix it, the hotend itself may be leaking.

PETG strings even when "perfectly" tuned. Best results come from:

TPU oozes because the filament compresses inside the extruder before pushing through. Solve by lowering retraction speed to 20 mm/s and retraction distance to 0.6 mm. Print slower (25 mm/s) so you don't need much pressure in the melt zone.

Nylon absorbs ambient humidity in hours. Print directly from a dryer set to 80 °C. Without that, no setting will produce clean nylon.

Recommended articles