Almost every filament absorbs moisture from the air. Wet filament boils inside the nozzle: it pops, bubbles and strings, and gives weak, rough parts. Drying it is the fix, but each material has its own temperature: going over deforms the spool and falling short does nothing.
Filament drying temperature chart
Medians from the datasheets that state a drying step, sorted from highest to lowest temperature. If your spool comes with its own recommendation, follow the spool.
How to tell if your filament is wet
- You hear crackling or small pops while extruding.
- Bubbles, pores or a rough surface appear.
- There is a lot more stringing than with a fresh spool.
- Layers bond worse and the part breaks easily.
- With materials like PVA or TPU, the strand feels soft or sticky.
Nylon, PVA, TPU and polycarbonate are the most sensitive. PETG notices it quite a lot and PLA a little less, although it also ends up taking on moisture.
Filament dryer: what to look for when buying one
- Real maximum temperature: it must reach what the most demanding material you plan to use asks for.
- Temperature control and a timer so you can leave it drying unattended.
- Air circulation and an outlet: if the moisture is not carried out, the filament dries much worse.
- Capacity: one or several spools, and whether it takes cardboard or oversized spools.
- Printing from inside: dryers with a filament outlet let you print highly hygroscopic materials without them taking on moisture again.
Drying filament in the oven or on the heated bed
A kitchen oven works if it holds low temperatures accurately, which many do not: an oven that swings can overshoot the glass transition temperature and fuse the windings together. Use a separate thermometer and leave the door ajar. Some plastic spools deform before the filament itself does, so watch the spool too. The heated bed with a box on top is an emergency solution and less even.
How to store dry filament
Once it is dry, keep it in a sealed bag or box with desiccant (silica gel) and, if you can, a small hygrometer so you know when to change the desiccant. The most sensitive filaments are best printed straight from a dry box.
Frequently asked questions about drying filament
What temperature do you dry PLA at?
The datasheets that state it suggest low temperatures, around 50 °C. Going over brings the spool close to its glass transition and the windings can stick together.
How long do you have to dry filament?
It depends on the material and on how much moisture it has. The table on this page lists the times from the datasheets, which usually run from a few hours to overnight.
Is a filament dryer worth it?
If you use nylon, TPU, PVA or polycarbonate, yes: they are almost impossible to print well when wet. With PLA and PETG, a good box with desiccant is usually enough.