3D model supports in slicers cause stringing because the nozzle oozes molten plastic when moving between the model and supports.
- **Why it happens**: Slicers plan support paths that require the nozzle to travel across gaps. If retraction (pulling plastic back into the nozzle) or temperature settings aren’t optimized, molten plastic drips during these moves, creating thin strings.
- **Common scenarios**: Printing models with overhangs >45° (like arches or internal cavities) that need supports, or using filaments like PLA which are more prone to oozing.
- **How to reduce it**: Increase retraction distance/speed in the slicer, lower the nozzle temperature by 5-10°C, or enable "wipe" settings to clear excess plastic before the nozzle moves between the model and supports.