If your prints suddenly look rough, stringy or weak — and nothing else changed — the culprit is often moisture. Filament absorbs water from the air, and water vaporized by the hot nozzle wreaks havoc on layer quality. Here is how to spot wet filament and keep your spools dry.
Signs Your Filament Is Wet
- Popping / clicking sounds at the nozzle as steam escapes.
- Stringing and blobs that appear out of nowhere.
- Dull, bubbly or rough top surfaces.
- Reduced layer adhesion and brittle, snapping filament.
Why Different Materials Need Different Care
| Material | Sensitivity | Drying |
|---|---|---|
| PLA / PLA+ | Low–moderate | ~45–50 °C for 4–6 h |
| PETG | Moderate–high | ~60–65 °C for 4–6 h |
| ABS | Moderate | ~80 °C for 4–6 h |
| TPU | Very high | ~65–70 °C for 6–8 h |
Drying Methods That Work
Option 1: A purpose-built dryer
A filament dryer with temperature control removes all guesswork. Set the target temperature, walk away, and spool is ready in a few hours.
Option 2: Oven or dehydrator (carefully)
- Use a lab-calibrated temperature reading — home ovens can overshoot and melt spools.
- Never exceed the material's glass-transition temperature.
- Mind the lid/fan shelf to avoid hotspots.
Storage: Keep It Dry After Drying
- Store filament in sealed bags with desiccant between jobs.
- Label spools with material and print temperature to avoid mix-ups.
- For frequent users, a filament drying box that combines storage, desiccant and active drying keeps spools ready 24/7.
Also Check Before You Blame the Filament
- Confirm nozzle temperature and speed match the material spec.
- Ensure a clean, properly leveled build surface (a cold PEI build plate helps adhesion without heating).
- Retract carefully to reduce stringing on moisture-prone materials.
Start With Dry, Consistent Filament
A premium PLA+ spool performed at the right temperature and kept dry will out-print a wet spool of supposedly "better" material any day. Drying first is the single cheapest quality upgrade in FDM.