Retraction is a slicer command that briefly pulls filament back from the hot nozzle before a travel move, relieving pressure to prevent oozing and the fine strings it leaves across a 3D print.
Retraction is a motion instruction in which a 3D printer's extruder reverses the filament a short distance before the nozzle travels between two printed regions. Drawing the molten filament back from the melt zone creates negative pressure at the nozzle tip, stopping material from leaking out while no extrusion is intended.
The primary purpose of retraction is to eliminate stringing — the thin, hair-like wisps of plastic left spanning gaps when a nozzle oozes during travel moves. Because oozing during non-printing movement is the most common cause of these strings, retraction is typically the first setting adjusted when a 📝3D Printing part shows whiskers or cobwebbing.
Two parameters define the behavior: retraction distance, the length of filament withdrawn, and retraction speed, how quickly it is pulled. Direct-drive extruders usually need only 0.5–2 mm because the drive gear sits close to the nozzle, whereas Bowden setups may require far more — up to around 15 mm — to compensate for the long, flexible path between gear and hot end. Excessive retraction can grind the filament or introduce gaps in the print, so values are commonly tuned through calibration.