Why storage beats fixing damp filament
Bambu explains the mechanism plainly: moisture in filament vaporises in the hot nozzle, the melt expands and bubbles, and prints show stringing, oozing, holes, rough surfaces and lower strength [1]. Drying reverses that, but only until the filament picks moisture up again.
Its storage figures show how fast that happens. Most filaments stay dry only while kept below 20% RH; at 20% RH they generally remain dry for 2 to 7 days, and at around 55% RH freshly dried filament can absorb enough moisture to affect quality within 2 to 12 hours, depending on how hygroscopic it is [1]. Keeping filament sealed is therefore a daily habit, not a once-a-month fix.
Drying temperatures and times by material
The table uses Bambu’s drying appendix, which gives separate settings for a forced-air oven, the AMS 2 Pro and the AMS HT, plus whether desiccant is needed during printing [1]. Bambu’s material table on another page gives slightly different oven figures, 55 °C for 8 hours for PLA and 70 °C for 8 hours for PETG [2]; either set is a reasonable target, and the lower one is gentler on spools.
| Material | Dry before use? | Forced-air oven | AMS 2 Pro | AMS HT | Desiccant while printing |
|---|---|---|---|---|---|
| PLA Basic / Matte | Recommended | 50 °C, 8 h [1] | 45 °C, 12 h [1] | 45 °C, 12 h [1] | Not required but recommended [1] |
| PETG | Recommended | 60–65 °C, 8 h [1] | 65 °C, 12 h [1] | 65 °C, 12 h [1] | Not required but recommended [1] |
| TPU 95A HF | Required | 70 °C, 8 h [1] | 65 °C, 12 h; may not fully dry [1] | 75 °C, 18 h [1] | Required [1] |
| PC | Required | 75–85 °C, 8 h [1] | Not compatible [1] | 80 °C, 8 h [1] | Required [1] |
| PA6-CF/GF, PAHT-CF (nylon) | Required | 75–85 °C, 8–12 h [1] | Not compatible [1] | 85 °C, 12 h [1] | Required [1] |
Which materials absorb water fastest
Bambu’s tables put nylon, PC, TPU, PVA and PLA Wood in the “drying required” group, and its material table marks PETG HF and PETG Translucent as required too, while ordinary PLA and PETG are “recommended” [1][2]. Treat the required group as filaments that must live in a sealed box between prints.
Nylon is the extreme case. Bambu says PA-based filaments absorb a significant amount of moisture after about three months in open air, after which they are very hard to dry in a normal oven at 80–90 °C, so unused nylon must be sealed with desiccant [1]. PC has a different problem: repeated heat-and-cool drying cycles can make the filament brittle and prone to breaking in the feed path, so keep it sealed after one drying rather than re-drying before every print [1].
Dryers and multicolour units with built-in drying
Bambu’s AMS 2 Pro dries at up to 65 °C, reaches that only when the room is above 25 °C, must be connected to the printer to dry, and needs a separate switching adapter per unit on A1, P1 and X1 printers [3]. Bambu says it suits filaments needing no more than 65 °C, and that you must remove low-temperature filament such as PLA before drying hotter ones such as ABS [1]. Bambu says all filaments can be dried in the AMS HT, though some such as PVA, PPA-CF and PPS-CF may not dry fully [1]; it needs its own included power supply for drying and was listed at $119 [4].
Anycubic’s ACE 2 Pro dries between 35 °C and 65 °C for 2 to 24 hours, can dry while printing, and cannot dry while disconnected from a powered-on printer [8]. Creality’s CFS is sold as moisture-proof storage, and Creality Print shows the humidity inside it [9][10]; the pages we checked did not describe a heater in the CFS, so pair it with a separate dryer for damp spools.
| Option | Max drying temperature | Type or capacity | Listed price |
|---|---|---|---|
| Bambu AMS 2 Pro | 65 °C [3] | Multicolour feeder with drying [3] | $229, typical $299 [3] |
| Bambu AMS HT | Up to 85 °C for nylon in Bambu’s table [1] | Feeder with drying and a bypass outlet for soft filament [4] | $119, typical $139 [4] |
| Anycubic ACE 2 Pro | 65 °C [8] | Four feed tubes [11]; Anycubic’s FAQ answer on spool capacity says two at a time, so confirm before buying [8] | Not checked for this guide |
| Creality Space Pi V2 | 75 °C [5] | Not stated on the store page [5] | $84.90 [5] |
| Creality Space Pi V2 Plus | 75 °C [7] | 2 [7] | $89.00 [7] |
| Creality SpacePi X4L | 75 °C [6] | 4 [6] | $119.00 [6] |
Starter storage checklist
A workable set-up for a first printer is cheap. Only the dryer has an official price here; containers, hygrometers and desiccant vary by local shop.
- An airtight box or bag per open spool, with desiccant inside; Bambu says to store dried filament sealed with desiccant [1].
- A hygrometer in the box, and a target below 20% RH [1].
- Silica gel you can regenerate: Bambu dries its beads at 80–90 °C in an oven for 1–3 hours and warns never to exceed 100 °C [1].
- A dryer only if you print PETG, TPU, nylon or PC regularly; Creality listed its Space Pi V2 at $84.90 and the two-spool Space Pi V2 Plus at $89 [5][7].
- Never a microwave or kitchen oven; Bambu says heat is uneven and can damage spools [1].
- If your filament came without a spool, Bambu says to fit it onto a reusable spool before drying [1].
Questions before you decide
What humidity should I store filament at?
Bambu Lab says most filaments only stay dry when stored below 20% relative humidity, and typical indoor air is around 45–65% RH, so use a sealed container with desiccant and a hygrometer.
Can the AMS 2 Pro dry nylon or PC?
Bambu’s drying table lists PC and nylon as not compatible with AMS 2 Pro drying, which tops out at 65 °C. The same table gives 80 °C for 8 hours for PC and 85 °C for 12 hours for nylon in the AMS HT.
Can I dry filament on my printer’s heated bed?
Bambu describes heated-bed drying with a cover on enclosed H, X, X2D, P2S and P1S printers, but says open-frame printers such as the A1, A1 mini, A2L and P1P cannot be used to dry filament.
Does the Anycubic ACE 2 Pro dry filament without the printer on?
No. Anycubic says the ACE 2 Pro must be connected to a powered-on printer set to material drying mode and cannot dry while disconnected.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- Bambu Lab Wiki: Filament drying recommendations Accessed 30 Oct 2026
- Bambu Lab Wiki: Filament guide, storage and material specifications Accessed 30 Oct 2026
- Bambu Lab US store: AMS 2 Pro Accessed 30 Oct 2026
- Bambu Lab US store: AMS HT Accessed 30 Oct 2026
- Creality store: Space Pi V2 filament dryer Accessed 30 Oct 2026
- Creality store: SpacePi X4L filament dryer Accessed 30 Oct 2026
- Creality store: Space Pi V2 Plus filament dryer Accessed 30 Oct 2026
- Anycubic Wiki: ACE 2 Pro FAQ Accessed 30 Oct 2026
- Creality Wiki: Guide to using CFS in Creality Print Accessed 30 Oct 2026
- Creality store: CFS Creality Filament System Accessed 30 Oct 2026
- Anycubic Wiki: ACE 2 Pro warm tips Accessed 30 Oct 2026
Sources link directly to providers. Product buttons may use separately labeled affiliate links. Read our disclosure.