Short answer: store filament in a sealed container with desiccant at under 25% relative humidity, and dry any spool that has been in open air for more than a week or two. In Sydney, Brisbane and most of coastal Australia, ambient humidity sits at 60–80% for much of the year — an open spool on a shelf is absorbing moisture right now, and wet filament is the number-one cause of stringing, popping sounds, rough surfaces and weak parts.
How humidity actually damages filament
PLA, PETG, TPU and especially nylon are hygroscopic — they pull water molecules out of the air into the plastic itself. When that filament hits a 210–250 °C nozzle, the water flashes into steam inside the melt. The result: hairs and strings between features, tiny bubbles and pockmarks on surfaces, audible crackling while printing, and parts that are measurably more brittle.
How fast does it happen in Australia?
- PLA: noticeably degraded print quality after 1–2 weeks in open Sydney air; badly affected after a month.
- PETG: similar timeline, and it shows moisture more obviously (heavy stringing).
- TPU and nylon: can be visibly compromised within 24–48 hours. Nylon should essentially never be stored in open air.
Dry inland climates (Canberra winters, much of regional Australia) are more forgiving, but summer storms and humid nights still push spools past the safe zone.
The storage setup that works
- Sealed container: a large airtight tub, vacuum bags with a valve, or the original zip bag if it still seals. Cereal-style dispensers with silicone seals work well for active spools.
- Desiccant: rechargeable silica gel. Regenerate it in the oven (or a filament dryer) at ~120 °C for 1–2 hours when the indicator turns from orange to green (or blue to pink).
- A hygrometer in every box: this is the part most people skip, and it is the part that removes all guesswork. A small digital thermo-hygrometer tells you at a glance whether the box is at a safe 15–25% or has crept back to 40%+.
When (and how) to dry filament
Storage prevents moisture; drying removes it. Dry a spool when prints start stringing, when the surface looks rough, when you hear popping — or any time a spool has lived in open air for weeks.
- PLA: 45–50 °C, 6–8 hours
- PETG: 60–65 °C, 6–8 hours
- TPU: 55–60 °C, 8+ hours
- Nylon / PAHT-CF: 70–80 °C, 8–12 hours
A purpose-built filament dryer is the low-effort option and doubles as a feed box for long prints. An oven works if it holds temperature accurately at low settings — verify with a thermometer, because many ovens overshoot badly below 60 °C and will soften a PLA spool into modern art.
Does the AMS protect filament?
Partly. The Bambu Lab AMS is sealed and has desiccant slots, making it good storage for the four active spools — keep its desiccant fresh and it will hold a safe humidity. But the AMS is not a dryer: it cannot rescue a spool that is already wet. Dry first, then load. (The AMS 2 Pro adds an actual drying function — one of the reasons it's a worthwhile upgrade; see the Bambu Lab range.)
Buying in bulk without waste
Bulk deals like our 10-roll BIQU PLA GO boxes only make sense if the spare rolls stay dry. The good news: unopened, properly sealed spools with healthy desiccant keep for a year or more. Leave the vacuum bags sealed until you need each roll, store the box somewhere cool, and rotate oldest-first.
FAQ
What humidity should 3D printer filament be stored at?
Under 25% relative humidity. Between 25–40% is a warning zone; above 40% your filament is actively absorbing moisture.
Can I fix wet filament, or is it ruined?
Almost always fixable. Drying at the right temperature for 6–12 hours restores nearly all print quality. Only filament stored wet for many months (or visibly degraded) is a lost cause.
Do I need to dry brand-new filament?
Often, yes. Vacuum packaging helps but is not perfect, and spools may have been packed months before reaching you. If a new spool strings, dry it before blaming the filament.
3D BRO stocks filament, dryers and accessories in Sydney with fast Australia-wide shipping — and we print every day, in Sydney humidity, so these numbers come from experience.
