Stringing and oozing


Stringing and nozzle oozing are the two most common printing problems that have same the same root cause. Very high printing temperatures and/or using incorrect retraction settings.

Stringing, also known as hairy prints, occurs when small strings of filament are left on a printed model. This usually happens, when the filament oozes out of the nozzle while the extruder is moving to a new location. You can see this as a marginal line of filament left between the objects. However, this can be solved by changing a couple of settings in PrusaSlicer. You should start by checking a parameter known as Retraction. What does retraction do? When the extruder has finished printing one section of your model, the filament is then pulled back into the nozzle. Once the extruder moves to the next location the printing process continues – the filament is pushed back out and it starts extruding from the nozzle again.


Flexible filaments usually need longer retractions, because the material stretches while being pulled back to the nozzle. Flexible materials are a special case and need a lot of tweaking and tuning.

Preventing strings from happening:

Use correct value for retraction. Users often increase retraction to meaningless values, so check the PrusaSlicer settings and make sure that you have the retraction set to a maximum of 2 mm.


Stringing from material blob on noozle. If you print for a long time from a single type of filament, such as PET-G, the filament can create a thin layer in the nozzle. This can cause stringing as the strands of the filament stick to the surface of the print. Therefore, thoroughly clean the nozzle before printing and make sure that any dirt or remnants of previous filaments are removed from the nozzle.

Use correct printing settings – We highly recommend using our official (factory default) preset settings in PrusaSlicer. However, if you are printing with your own settings, make sure that you have the retraction settings configured correctly. Retraction settings can be found in PrusaSlicer in Printer Settings – Extruder 1.

Try to lower the nozzle temperature – Lowering the temperature decreases the occurrence of strings. Try decreasing the nozzle temperature by 5 – 10°C and check whether there’s less stringing.

Or just use a heat gun! – If you don’t feel like tweaking any of the settings, well, then there is an alternative. You can get rid of the strings with a heat gun (or possibly with a lighter – but be very careful). Set it to around 200°C and aim at the strings for one or two seconds. This will melt the strings, and the printed object should remain undamaged.