Drying filament: temperatures, duration and methods
are explained briefly when you hover over or tap them.
Almost all filaments absorb moisture from the air. The technical term for this is hygroscopic. A spool that lies open in the room for a few weeks can absorb so much water that it prints noticeably worse. The good news: drying almost always reverses this.
How do you recognise damp filament?
- Crackling or popping while printing, because water evaporates in the nozzle
- More strings between the parts than usual
- Rough, matte or blistered surface
- Brittle parts and poor adhesion between the layers
- With very damp filament: steam or small wisps at the nozzle
The crackling in particular is an unmistakable sign. If you hear it, drying is almost always worthwhile.
Which materials are sensitive?
| Material | Sensitivity | Guide value for drying | Duration |
|---|---|---|---|
| PLA | low to medium | 45 to 55 °C | 4 to 6 hours |
| PETG | medium | 60 to 65 °C | 4 to 6 hours |
| TPU | high | 50 to 55 °C | 6 to 8 hours |
| ABS, ASA | medium | 70 to 80 °C | 4 to 6 hours |
| PA (nylon) | very high | 70 to 80 °C | 8 to 12 hours |
| PC | high | 75 to 80 °C | 6 to 8 hours |
| PVA | extremely high | 45 to 55 °C | 6 to 10 hours |
The values are guide values. The manufacturer’s information on the spool or in the datasheet always takes priority. Many manufacturers now print drying temperature and duration directly on the label.
It is important to stay below the softening temperature of the material. With PLA this is already reached at around 55 to 60 °C. If it is too hot, the windings on the spool stick together and the spool is unusable.
The methods compared
Filament dryer
Small boxes that hold one or more spools. They heat to an adjustable temperature and often have an opening through which the filament runs directly to the printer. That way you can dry and print at the same time.
Advantage: exact temperature, simple. Disadvantage: cheap models often only reach 50 to 60 °C, which is not enough for nylon or PC. You will find current models with maximum temperature and price in the filament dryer comparison.
Multi-colour system with drying
Some multi-colour systems can actively dry filament during storage, such as newer AMS versions from Bambu Lab or the ACE systems from Anycubic. Whether they can, and up to what temperature, is stated in the datasheet of the respective system.
Food dehydrator
A food dehydrator for fruit often works well if the spool fits inside. Sometimes you have to remove trays for this. Check the temperature with a thermometer, as the scale is often inaccurate.
Oven
Works in an emergency, but is risky. Many ovens fluctuate strongly at low temperatures and clearly exceed the set value. Plastic spools can warp. If at all, only with an oven thermometer and fan assistance, and never unattended.
Storing properly
Drying only helps if the filament stays dry afterwards.
- Airtight box with a lid seal, for example a storage box from the DIY store or a vacuum bag
- Desiccant in the box, for example silica gel. Variants with a colour change show when they are saturated. Saturated silica gel can be dried again in the oven.
- Hygrometer in the box, a small digital device for a few euros. As a rule of thumb: under 20 % relative humidity is good, as low as possible for nylon and PVA.
- Partly used spools back in the box after printing, do not leave them hanging on the printer
Which box, whether vacuum bag or dry box, and how to dry desiccant again is covered in detail under Storing filament properly.
Do I have to dry every new spool?
Not necessarily. New spools are usually vacuum-packed and dry. With PLA you can generally get started straight away. With nylon, PC, PVA and often TPU as well, drying before the first print is still worthwhile, because even a short time in the air is enough.
You will find more on the individual materials in the overview Which filament for what? and in the glossary.