How to dry filament: the right temperature and time for each material

Short answer

Dry filament at the temperature and time its material calls for, using a filament dryer, food dehydrator, or low oven. PLA dries at 40 to 50 C, while PETG needs 60 to 65 C, and too much heat fuses or warps the spool. The numbers below come from the Bambu and Prusa drying tables.

Why filament absorbs water

Most 3D-printing filament is hygroscopic, which means it pulls moisture out of the air around it. PLA pulls less water than PETG, nylon, or TPU, but any spool left open in a humid room slowly gains moisture. The water sits inside the plastic instead of on the surface, so a quick wipe does nothing. Per Bambu’s drying guide, the fix is low, steady heat held long enough to drive that moisture back out.

Signs your filament is wet

A wet spool shows itself at the nozzle. You hear popping or hissing as trapped water turns to steam, and that steam can spatter the print. The surface turns cloudy, rough, or frosted where it should be smooth. You may also see fine strings between travel moves and weaker layer adhesion. One sign alone does not prove the filament is wet, but two or three together point to a spool that needs drying.

Four ways to dry filament

A dedicated filament dryer is the most consistent option. You set the temperature, close the chamber, and some models let you print straight from the dryer. A food dehydrator does the same job for less money, but check the real temperature with a thermometer, because the dial is often off.

A kitchen oven works when it can hold a true low temperature. The heated-bed method sets the spool in a sealed box on a warm bed and works as a backup for one spool at a time. For long prints with PETG, nylon, or TPU, printing from a dryer while you run the job keeps the filament dry the whole time.

Drying temperature and time by material

Each material dries at a different temperature, and pushing the heat higher does not dry it faster or safer. The values below come from Bambu’s dry-filament table and Prusa’s drying guide, with the PETG oven and bed values from Bambu’s PETG page. Stay inside these ranges, and re-dry a spool that has sat open for weeks.

Keep it dry after you dry it

Drying a spool once is not the end of the job. Filament starts pulling moisture back out of the air as soon as it sits open, so store it sealed. Put the spool in an airtight bag or box with desiccant inside. Molecular sieve beads hold the air near 10 percent relative humidity, and a small hygrometer tells you when the desiccant is spent, per Maker’s Pet’s desiccant guide.

For the next step, the filament storage guide walks through sealed-container setup, and the best filament dryer page covers gear that dries and prints at the same time.