Filament is hygroscopic — it drinks moisture straight out of the air. Wet filament is the hidden cause of popping sounds, stringing, weak layers and rough surfaces that appear “for no reason” weeks after you opened a spool. Here is how to keep every roll print-ready.
How to tell filament is wet
- Popping or crackling at the nozzle as trapped water flashes to steam.
- Stringing and blobs that were not there when the spool was new.
- Brittle, weak prints and a rough, hazy surface.
Which filaments absorb moisture fastest
Nylon (PA) and TPU are the thirstiest, followed by PETG. Even PLA degrades over months in a humid room. If you live somewhere humid, assume every open spool is slowly absorbing water.
Store it right
- Keep spools in airtight boxes with desiccant — silica gel that you recharge in the oven.
- Aim for under 15–20% relative humidity; a cheap hygrometer tells you where you stand.
- For the thirstiest materials, print straight from a heated dry box.
Already wet? Dry it
A filament dryer or a low oven (follow the material’s guidance, typically 45–70 °C for several hours) drives the water back out and often revives a “dead” spool.
Keep your filament perfect from day one with our storage & drying gear — dry boxes, desiccant and hygrometers.