Every fall I get the same wave of messages: "my prints were fine all summer and now everything is stringy and popping." Nine times out of ten it has nothing to do with the printer. It's the filament, and specifically, how much water it's soaked up sitting on a shelf.
I run a Flashforge Adventurer 5X with its enclosed chamber, a Bambu Lab A1 with the AMS feeding four spools at once, and a Felfil EVO extruder that turns ground-up scrap and pellets into my own filament. Between those three setups I've had every version of the "wet filament" problem there is, and I've slowly built a storage and drying routine that actually works instead of one I just feel guilty about skipping. Here's what I've learned, including a few things I picked up from r/3Dprinting and r/BambuLab that saved me from re-learning lessons the hard way.
Why This Matters More As the Weather Turns
Most FDM filaments are hygroscopic, meaning they pull moisture straight out of the air. PLA is the most forgiving. PETG, nylon, TPU, PVA, and anything with a wood or metal fill are much thirstier and start showing problems after just a day or two exposed to humid air. The tricky part is that humidity doesn't move in a straight line through the year. Late summer and early fall, when outdoor humidity is still high but a lot of us start running the heat at night, is exactly when indoor air swings around the most and filament that was fine in July starts misbehaving in September.
What Wet Filament Actually Looks Like
You don't need a hygrometer to diagnose this one, though it helps. The tells are pretty consistent:
Audible popping or crackling at the nozzle as steam pockets escape mid-print. Fine "hair" stringing between features even with retraction dialed in correctly. A rough, matte, almost sandpapery surface finish where you expect gloss. Layer adhesion that looks fine visually but snaps or delaminates under light stress. Bubbling or a slightly foamy texture on the extruded line itself, especially visible on PETG and nylon.
If you're chasing stringing settings in your slicer for the third week in a row and nothing sticks, stop tuning retraction and go weigh a fresh spool against the one on your printer. It's usually not your settings.
What I've Learned Running an AMS, an Enclosed Printer, and a Filament Extruder Side by Side
The AMS Changes the Math
A single spool sitting in a dry box is easy to manage. Four spools loaded into a Bambu AMS, potentially for a multi-day multicolor print, is a different problem entirely, because every spool is exposed to chamber air the whole time the job runs. I learned this the annoying way on a long multicolor piece where the PETG spool in slot 3 started stringing on day two while the other three PLA spools were fine. Now I only load moisture-sensitive materials into the AMS right before I start a print, and I keep desiccant packs cycling in every bay, not just the ones I'm actively pulling from. A handful of rechargeable silica gel desiccant packets living inside the AMS housing costs you nothing in print quality and buys real peace of mind.
An Enclosed Chamber Isn't a Dry Box
People assume that because the Adventurer 5X has an enclosed, heated chamber, filament stored on the built-in spool holder is protected. It's not, at least not in the way a sealed dry box is. The chamber keeps heat and drafts out for printing ABS and other high-temp materials, but it isn't sealed against ambient humidity when the door's been opened and closed a dozen times over a multi-day job. If I'm running the 5X for anything longer than a day, I still pull spools I'm not actively using and store them properly rather than leaving them mounted "just in case."
Homemade Filament From the Felfil Is the Most Vulnerable of All
This is the one that surprised me most. When you buy commercial filament, it's been extruded, dried, and usually vacuum-sealed with desiccant at the factory before it ever reaches you. When you're making your own filament on a Felfil EVO from recycled scrap or pellets, none of that happens automatically. Whatever moisture is in your source material, plus anything absorbed during extrusion and spooling, is locked right into the strand. I now dry my raw pellets and shredded scrap before I ever feed them into the extruder, and I treat every freshly extruded spool as "wet until proven dry" rather than assuming it's ready to print. Skipping that step is the single biggest reason my early Felfil prints looked worse than the commercial filament I was trying to replace.
Building a Storage Routine That You'll Actually Keep Up
The honest truth is that the best drying setup is the one you won't abandon after two weeks. Here's the tiered approach I actually use, cheapest and simplest first:
Tier 1: Passive Storage With Desiccant
For PLA and anything you're printing within a few days of opening, a sealed container with desiccant is enough. Vacuum-seal bags or airtight totes with a couple of rechargeable silica gel packs thrown in will keep a spool print-ready for weeks. The rechargeable ones matter more than people think, since you just pop them in a low oven or a filament dryer to reset them instead of buying new packets every month.
Tier 2: An Active Dry Box for Materials You Print In
If you regularly print PETG, TPU, or nylon, or if you run an AMS with mixed materials loaded for days at a time, get a box that prints directly from inside a sealed, low-humidity enclosure rather than just storing filament between sessions. The BIGTREETECH ViViD dryer box is built for exactly this: multi-spool storage that keeps humidity down while you're actively feeding filament to the printer, which is a real upgrade over pulling a spool out of a tote, printing, and hoping you remember to seal it back up.
Tier 3: A Dedicated Filament Dryer for Anything You're Not Sure About
When a spool has clearly absorbed moisture, or when you're prepping raw or recycled material for the Felfil, you need active heat over time, not just a low-humidity environment. This is where a real filament dryer earns its keep. The SUNLU FilaDryer E2 goes up to 110°C / 230°F, which covers PLA and PETG comfortably and gets you into real engineering-material territory for nylon and other high-temp filaments that need a proper bake, not just a warm afternoon in a box.
A Few Things Reddit Got Right
Browsing r/3Dprinting and r/BambuLab threads on this topic over the last year, a few pieces of community wisdom held up when I tested them myself. Drying time matters more than drying temperature; a lot of people crank heat and cut time short, when a longer, gentler dry actually pulls more moisture out without risking the spool warping or fusing to itself. Weighing a spool before and after drying is the closest thing to a real diagnostic tool most of us have at home, since a spool that's lost 10-30 grams over a few hours in the dryer was genuinely wet, and one that barely moves probably didn't need it. And more than one experienced printer pointed out that nylon and other engineering filaments should basically be assumed wet the moment the factory seal is broken, full stop, no exceptions.
The Bottom Line
If you've been fighting stringing, weak layers, or a rough finish and you've already gone down the rabbit hole of retraction and temperature tuning, back up and check moisture first. It's the cheapest fix in the entire hobby: a bag of desiccant and twenty minutes of patience solves more print quality problems than any slicer setting I know. Whether you're pulling from a single spool, running an AMS with four materials loaded at once, or drying your own recycled filament fresh off a Felfil extruder, the fix scales with the setup, but the underlying rule never changes. Dry filament prints better. Every time.
You can find the storage and drying gear mentioned here, along with the rest of our filament and materials lineup, on the site.
