How to dry and store 3D-printing filament (2026)
Half of "my printer is broken" is actually wet filament. Plastic absorbs moisture from the air; when that water hits the hot nozzle it flashes to steam, and you get stringing, popping, weak layers, and a rough surface. The fix is cheap and it's the single biggest quality upgrade most people skip. Here's the exact system I use.
Signs your filament is wet
- Stringing and wisps between parts that tuning won't fix
- Popping or crackling sounds from the nozzle
- Rough, bumpy, or hazy surfaces
- Parts that snap instead of flex (brittle layers)
PETG, TPU, and nylon drink moisture fast; even PLA does over time.
The three-part system
1. Dry it — an active dryer
An active dryer heats and circulates air to pull moisture back out. I use the SUNLU S4 — 4 spools at once, 3 circulation fans, up to 70°C, with a humidity readout so you can watch it drop. You can also print straight from it, which is the move for TPU and nylon.
Rough temps and times (start conservative; the S4 tops out at 70°C):
| Material | Dryer temp | Time |
|---|---|---|
| PLA | 45–55°C | 4–6 h |
| PETG | 55–65°C | 4–6 h |
| TPU | 45–55°C | 4–8 h |
| ABS / ASA | 65–70°C | 4–6 h |
| Nylon (PA) | 70°C | 8–12 h |
2. Store it — an airtight bin + desiccant
Once dry, keep it dry. A gasketed airtight bin with a scoop of desiccant is all it takes. I use Fonday rechargeable silica-gel beads — they're orange and turn green when spent, so you can see at a glance when to recharge them. Bake them dry (or run them in the dryer) and reuse for years.
3. Keep desiccant in the AMS
The AMS isn't sealed enough to dry filament, but a pod of the same rechargeable desiccant inside it keeps loaded spools from creeping back up in humidity between prints. Swap or recharge when the beads turn green.
The routine that keeps prints clean
- New spool → dry it before the first big print.
- Store dried spools in a sealed bin with desiccant.
- Keep desiccant in the AMS and check the color monthly.
- Recharge green beads in the dryer and reuse.
That's it — a one-time dryer purchase plus a few dollars of reusable desiccant, and "why is this stringy?" mostly disappears.
Gear used
- SUNLU S4 filament dryer — the active dryer
- Fonday rechargeable silica-gel desiccant — bins + AMS
- Airtight storage bins — sealed storage
- The rest of my 3D-printing picks
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