Ever load a roll of filament, start printing, and your nozzle sounds like it’s frying up bacon?
That popping and crackling sound is one of the most common signs that your filament is wet.
A lot of makers assume their slicer settings are wrong when prints suddenly start looking stringy or rough. But very often the real issue isn’t temperature, retraction, or speed — it’s moisture that the filament absorbed from the air.
Some filaments barely care about humidity, while others start soaking up moisture the moment you open the bag. Understanding which materials are sensitive to moisture can save you a lot of frustration and troubleshooting.
Let’s break down which filaments are the most hygroscopic and how you can keep them dry.
What Does Hygroscopic Mean?
When people say filament is hygroscopic, it simply means the material absorbs moisture from the air.
When filament absorbs too much moisture, the water inside the plastic turns into steam as it passes through the hot nozzle. That steam creates several problems during printing:
• Popping or sizzling noises
• Excessive stringing
• Rough or bubbly surfaces
• Weak layer bonding
• Inconsistent extrusion
If your settings haven’t changed but your prints suddenly look worse, moisture is often the culprit.
Moisture Sensitivity of Common 3D Printing Filaments
Different materials absorb moisture at very different rates. Some can sit out for weeks without issues, while others can start degrading within hours.
Low Moisture Sensitivity
PLA
PLA is one of the most forgiving filaments when it comes to humidity. It can absorb moisture, but it does so slowly.
If PLA sits out in a humid room for long periods, it may eventually cause printing issues. But compared to many other materials, it handles ambient moisture fairly well.
Low to Mild Moisture Sensitivity
ABS and ASA
ABS and ASA behave very similarly when it comes to moisture.
They can absorb moisture over time, but they generally tolerate normal room humidity better than many other engineering plastics.
If stored reasonably well, moisture rarely becomes a major issue with these materials.
Moderate Moisture Sensitivity
PETG
This is where moisture issues start becoming more noticeable.
PETG already has a reputation for being a bit stringy, and moisture makes that problem worse. Wet PETG often produces:
• Extra stringing
• Slight popping sounds
• Rough surface finishes
If your PETG prints suddenly become stringy, moisture is often the reason.
Moderate to High Moisture Sensitivity
TPU (Flexible Filaments)
Flexible filaments like TPU absorb moisture much faster than rigid materials.
When TPU is wet, prints can become:
• Extremely stringy
• Rough and inconsistent
• Difficult to extrude smoothly
Keeping TPU dry can make a huge difference in print quality.
High to Extremely High Moisture Sensitivity
Some filaments are extremely sensitive to moisture and benefit greatly from controlled storage.
These include:
• Nylon
• Polycarbonate
• PVA
• PVOH
These materials can absorb moisture quickly enough that they often need active drying before printing, especially if they’ve been sitting out for a while.
Signs Your Filament Is Wet
If you’re not sure whether moisture is the problem, look for these common symptoms:
• Popping or sizzling from the nozzle
• Excessive stringing
• Rough or bubbly surfaces
• Inconsistent extrusion
• Prints suddenly getting worse without changing settings
If you hear the filament crackling during printing, moisture is almost always the cause.
How to Keep Your Filament Dry
The good news is that moisture problems are one of the easiest 3D printing issues to fix.
Use Sealed Storage Containers
Plastic storage bins with gasket seals work great for filament storage. These containers help keep humidity from entering while your filament sits on the shelf.
Add Desiccant Packs
Silica gel or other desiccants help absorb moisture inside storage containers. They’re inexpensive and can make a big difference for long-term filament storage.
Use a Filament Dryer
For moisture-sensitive materials like nylon or TPU, a filament dryer actively removes moisture before printing. Many dryers also allow you to print directly from the dry box.
Control the Room Humidity
One of the best solutions—especially if you have a lot of filament—is a room dehumidifier.
Lowering the humidity in your workspace helps prevent moisture from affecting all of your materials at once.
Just make sure the dehumidifier is sized correctly for the room. A unit that’s too small won’t remove enough humidity, and one that’s too large may heat the room unnecessarily.
The Big Takeaway
Some filaments are far more forgiving than others when it comes to moisture.
Most forgiving
PLA
ABS
ASA
Moderate sensitivity
PETG
TPU
High sensitivity
Nylon
Polycarbonate
PVA
PVOH
Sometimes improving your print quality isn’t about changing slicer settings or upgrading your printer.
Sometimes it’s as simple as keeping your filament dry.
Because a great print actually starts long before the nozzle heats up.
It starts with dry filament.