Stringing: where the wisps on a 3D print come from

Why strings form

When the nozzle travels from one place to another without printing, hot, runny plastic remains in the nozzle and slowly leaks out. That is how a thin strand forms. Prusa describes it on the page about stringing and oozing.

The usual causes are a nozzle temperature that is too high, badly set retraction and damp filament, see filament moisture.

Which materials are sensitive

PETG is more prone to strings than PLA, because it flows and sticks more. That is why the window of correct settings is narrower with it. PLA makes fewer strings, but it can too.

Stringing is mainly a cosmetic flaw and does not affect the strength of a part. On fine parts, such as figurines, though, it spoils the look.

What helps

• The right nozzle temperature, not higher than needed, see nozzle temperature.
• Retraction and Z-hop: retraction pulls plastic back into the nozzle and Z-hop lifts the nozzle on a move.
• Dried filament.
• Fewer travel moves in the model. Two pillars close together make fewer strings than pillars far apart.

Strings also form because PETG is stickier than PLA and leaks from the nozzle in a way that is harder to control. In multicolour printing there are more moves between colours, and so more chances for small strings.

For your order

We leave cosmetic strings where they are, because we do not do post-processing such as finishing. On ordinary parts it is a few hairs that can be removed with a lighter or a scalpel. If appearance matters to you, add a note. We always photograph the batch before dispatch.