STL files don’t inherently cause stringing, but their triangular facet structure can worsen it if the model has low resolution or geometric flaws.
STL uses tiny triangles to represent 3D shapes—low-res STLs (fewer/larger facets) create gaps or uneven surfaces, making slicer software miscalculate and trigger unnecessary filament extrusion (stringing).
To reduce stringing, first adjust printer settings (like retraction speed or temperature). Then use free tools like Meshmixer to fix STL errors (e.g., non-manifold edges) or increase facet count for better detail before slicing.