That popping sound from your nozzle isn’t normal. Neither is the stringing, the rough surfaces, or the parts that snap in half. Moisture is the most common invisible problem in 3D printing, and it’s easy to fix once you know what to look for.
Here’s a dirty secret of the hobby: most “bad prints” aren’t a printer problem or a settings problem. They’re a moisture problem. Filament absorbs water from the air. When that wet filament hits a 200°C nozzle, the water boils and turns to steam inside the plastic. The result is pops, bubbles, stringing, rough surfaces, and weak parts. The good news is it’s completely reversible.
1How to tell if your filament is wet
Moisture damage is sneaky because it builds up gradually. A spool that printed perfectly two months ago can produce garbage today if it’s been sitting out in the open. Here’s what to watch for:
What you’ll hear
The most obvious sign is popping or crackling from the nozzle during a print. That sound is tiny pockets of water boiling and bursting out of the plastic as it melts. If your printer sounds like a frying pan, your filament is wet. The louder and more frequent the pops, the worse it is.
What you’ll see
- –Stringing between parts. Thin wisps of plastic stretching between features that should be clean. Moisture causes erratic pressure in the nozzle, and plastic oozes where it shouldn’t.
- –Rough or bubbly surface texture. Instead of smooth layer lines, you’ll see a grainy, pitted surface — like the plastic was foaming as it came out. Because it was.
- –Small craters or pockmarks. Steam bubbles pop on the surface and leave tiny divots behind.
- –Poor layer adhesion. Parts that snap apart easily along layer lines. Steam between layers prevents proper bonding, and what looks like a solid part is actually held together by hope.
Extrude some filament into mid-air by pushing it through the nozzle manually. Watch and listen. Dry filament comes out smooth and quiet. Wet filament pops, sputters, and the extruded strand looks rough or bubbly. Takes ten seconds and tells you everything.
2Which filaments are most at risk
All filaments absorb moisture, but some are dramatically worse than others. Here’s how the common materials stack up:
| Material | Moisture risk | What to expect |
|---|---|---|
| PLA | Low–Medium | The most forgiving. Can sit out for weeks before you notice problems. Still degrades eventually. |
| PETG | Medium | Absorbs moisture faster than PLA. Stringing gets noticeably worse within days in humid conditions. |
| TPU | High | Soaks up water like a sponge. Will start popping and bubbling after just a day or two in open air. |
| Nylon | Very high | The most hygroscopic filament. Can absorb enough moisture in hours to ruin a print. Must be dried before every use. |
| ABS / ASA | Low | Relatively resistant. Not immune, but much more forgiving than the others. |
The rule of thumb: the more flexible or engineering-grade the material, the faster it absorbs moisture. PLA beginners get a lot of grace here. If you’re stepping up to PETG, TPU, or Nylon, storage becomes non-negotiable.
3How to dry wet filament
Wet filament isn’t ruined — it just needs a few hours of gentle heat to drive the water back out. The plastic itself is fine. You’re just evaporating what got absorbed.
What to use
A filament dryer is the easiest option — it’s a heated box designed to hold a spool and maintain a precise, low temperature for hours. Many also let you print directly from the dryer, which is ideal for moisture-sensitive materials like Nylon and TPU.
A food dehydrator with adjustable temperature works too. Just make sure it goes low enough — you want gentle heat, not melted filament.
Kitchen ovens have wildly uneven heat distribution and most can’t hold a steady temperature below 80°C. It’s very easy to warp or fuse an entire spool. A dedicated dryer or dehydrator is a small investment that pays for itself in saved filament.
Temperature and time by material
| Material | Temperature | Time |
|---|---|---|
| PLA | 45–50°C | 4–6 hours |
| PETG | 60–65°C | 4–6 hours |
| TPU | 50–60°C | 4–6 hours |
| Nylon | 70–80°C | 6–8 hours |
| ABS / ASA | 60–70°C | 4–6 hours |
Don’t rush it. Low and slow is the approach. Running a dryer overnight is perfectly fine and the most common method — start it before bed, wake up to dry filament.
4How to store filament so it stays dry
Drying is the rescue mission. Storage is the prevention plan. There’s no point drying a spool if you’re just going to leave it out on the shelf again. Here’s what actually works:
The basics: airtight + desiccant
The formula is dead simple: put the spool in a sealed container with silica gel desiccant packets. The container blocks humidity from the air. The desiccant absorbs whatever moisture is already trapped inside. That’s it. Your filament will stay dry for months.
- –Large plastic bins with gasket lids work great and hold multiple spools. IKEA SAMLA bins with clip lids are a community favourite.
- –Vacuum-sealed bags are the gold standard for long-term storage. Squeeze out the air, toss in a desiccant packet, and the filament will be bone-dry when you open it six months later.
- –Ziplock bags are better than nothing but not airtight. Fine for a week or two, not for long-term.
Desiccant tips
- –Use indicating silica gel — the kind that changes colour when it’s saturated (usually orange to green, or blue to pink). That way you know when to swap or recharge them.
- –Recharge your desiccant by baking it in an oven at 120°C for 2 hours. It drives the moisture out and you can reuse the same packets indefinitely.
- –One or two large packets per bin is plenty. Don’t go overboard.
Cardboard is more breathable than sealed plastic, which means our spools won’t trap moisture against the filament the way a sealed plastic spool can. But it also means the filament is a bit more exposed to ambient humidity once opened. The storage advice above applies to every spool — cardboard or plastic. Seal it up when you’re not printing with it.
Where to store
Keep your filament in a cool, dry, stable environment. A closet, a shelf in your print room, a drawer. Avoid garages, basements, and anywhere near an exterior wall where temperature and humidity swing with the weather. Canadian winters are dry (good), but spring and summer can be muggy (bad). Plan accordingly.
Your filament storage checklist
Dry filament, clean prints
Most people blame their printer, their slicer, or their settings when prints go sideways. Nine times out of ten, the answer is sitting right there on the spool — absorbed moisture that you can’t see but your nozzle definitely can. Spot the symptoms, dry it out, seal it up, and the problem disappears. Your printer was fine all along.
Keep your filament dry and your prints dialled. We’ve got you covered.
Browse our filament storage solutions — dryers, sealed containers, and desiccant kits — alongside every spool we sell. Free shipping on orders over $99 across Canada.
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