Last updated: October 21, 2026

How to dry 3D printer filament (and tell if it's wet)

Filament slowly soaks up moisture from the air. When a damp spool hits the hot nozzle, that water turns to steam, and your prints get stringy, rough and weak. The fix is simple: dry it at the right temperature, then store it sealed. Here's how to tell if you need to, and how to do it without ruining the spool.

Is my filament wet? The signs

• Popping, crackling or hissing from the nozzle while it prints or loads
• Sudden stringing on a model that used to print cleanly (Bambu Lab calls obvious stringing a typical sign of damp PETG)
• Rough, fuzzy or bubbly surfaces, sometimes with small gaps in the walls
• Brittle filament that snaps when you bend it, especially PLA that has sat out for a long time

If the spool has been sitting open for weeks, or you live somewhere humid, assume it needs drying before you start changing slicer settings. It's one of the most common reasons a "good" profile suddenly starts failing.

Which filaments need it most?

All filament absorbs some moisture, but not equally. PLA is the most forgiving and often prints fine straight from a fresh, sealed bag. PETG is much more sensitive: Bambu Lab calls it highly hygroscopic (it pulls water from the air) and recommends drying it before printing. TPU and nylon are even fussier. Not sure which you have? See PLA vs PETG for beginners.

Drying temperatures and times

Always check the label or website for your exact filament first, because brands differ. Here are two makers' published numbers as a starting point:

Prusa warns not to go above these temperatures, or the filament softens and the coils stick together, and not to dry for much longer than recommended either. When the two makers disagree, starting with the lower temperature is the safer choice. In Fahrenheit, 45 °C is 113 °F, 50 °C is 122 °F, 55 °C is 131 °F and 60 °C is 140 °F.

Three ways to dry it

1. A filament dryer (easiest)

A filament dryer is a small heated box that holds one or more spools at a set temperature. Set the temperature and time from the table above, let it run, and many models let you print straight out of the box so the spool stays dry while it feeds. This is the most reliable option for beginners and the one we'd buy first once you print PETG or live somewhere humid.

2. Your printer's heated bed (if your printer supports it)

Bambu Lab documents a method that uses the heated bed of some of its printers, with the spool covered so heat stays in. Its numbers for that method are higher and longer (for example 60 to 70 °C for 12 hours for PLA), flipping the spool every 6 hours. Only use this if your printer's maker describes it, and follow their steps exactly.

3. A kitchen oven (last resort, not for PLA)

Prusa's advice is to be careful: home ovens don't hold low temperatures precisely, many can't even be set low enough, and swings that don't matter for food can deform filament. PLA, which needs the lowest temperature, is the most at risk. If you use an oven for another filament anyway, put a separate oven thermometer next to the spool, stay below the maker's number, and don't leave it unattended.

After drying: test, then store it sealed

Print a small test, like a stringing test or the model that failed, and listen for popping. If it's quiet and clean, you're done. If not, the problem may be settings rather than moisture; our stringing guide walks through temperature and retraction next.

Then keep it dry. Dried filament starts absorbing moisture again in room air, so put it straight into a resealable bag or a plastic box with a tight lid and a few desiccant packets (the little drying sachets). Keep the bag and packet that came with new spools and reuse them. Our beginner toolkit lists the storage basics.

Quick answers by symptom

Sources

Checked October 21, 2026: Prusa Knowledge Base, Drying filament; Bambu Lab Wiki, Beginner's guide to filaments usage, Filament drying recommendations and PETG usage guide.

Your next step

Picking your next spool? See our best filament for beginners. Still seeing hairs on your prints after drying? Read how to fix stringing. Gaps or thin, weak walls instead? See how to fix under-extrusion.