How to Dry Wet Filament: Methods and Tools

Drying Temperature And Time Reference (Common Filaments) [a]
Filament Type	Drying Temperature (°C)	Typical Time (Hours)	What This Setting Is Trying To Do
PLA	50	4–6	Evaporate surface and near-surface moisture without softening the coil.
PETG	70	6	Push moisture out of a more hygroscopic polymer that often “hisses” when wet.
ABS	80	8–12	Deep drying for reliable extrusion and fewer bubbles in the bead.
TPU	50	6	Reduce micro-bubbles that show up as rough walls and inconsistent flow.
PC	80	8	Lower moisture for stable melt flow and cleaner bridges.
PVA	80	6	Dry aggressively; water-soluble supports can load moisture fast.
PA / Nylon (example: PAHT)	70	8	Bring moisture down before printing; nylon performance is moisture-sensitive.

These are manufacturer-style reference settings, not a universal law. Spool materials, pigments, fiber fill, and how tightly the filament is wound can change how fast moisture leaves the coil.

Wet filament is sneaky. The spool can look perfect, yet the melt behaves like it’s full of tiny landmines. The goal of drying is simple: remove enough water that extrusion becomes quiet, walls become cleaner, and your printer stops fighting random artifacts.

Moisture turns into vapor in the nozzle
Vapor makes bubbles and surface pitting
Drying is about temperature, airflow, and time
Storage matters as much as drying

Signs Of Wet Filament

Why Moisture Matters

What Drying Actually Does

Methods And Tools

Temperature Discipline

Material Workflows

How To Tell It’s Dry

FAQ

🔎 Signs Of Wet Filament

What You See On The Print

Random surface roughness that wasn’t there with the same profile.
Small pimples or craters that look like “micro-explosions” in the bead.
Stringing that feels unreasonably stubborn even after retraction tuning.
Weak layer bonding when the model should be solid.

What You Hear Or Notice At The Nozzle

Crackling, popping, or a faint hiss during extrusion.
Occasional bubbles and wisps while the filament flows.
Extrusion that alternates between “normal” and slightly foamy.

These symptoms are especially common with more hygroscopic families like polyamides, water-soluble supports, and many flexible materials [b].

💧 Why Moisture Matters

Inside the hotend, water does not stay “water”: It flashes into steam. Steam expands, creating micro-voids and pushing molten polymer away from where it should settle.
Moisture changes flow consistency: Even when the slicer is perfect, the extrusion can look inconsistent because the melt is literally outgassing.
Some polymers are more sensitive than others: Nylon is famously moisture-sensitive, and managing it is a whole process in industrial plastics because properties depend on staying within a moisture window [d].

Moisture Doesn’t Need A Lot Of Time To Become A Problem

Filament absorbs water from ambient air over time. For certain materials, just being out on a desk can be enough to show artifacts on the next long print. That’s why “dry once” often isn’t the final move; you dry, then you store properly.

🧠 What Drying Actually Does

Drying works when you get three things aligned: heat (to energize moisture), air exchange (to carry vapor away), and time (because inner layers of the spool dry slower than the outside).

The Coil Is The Real Challenge

Outer wraps dry first. Inner wraps are shielded and need longer exposure.
Airflow matters because trapped humid air slows evaporation.
Uniform temperature matters because local overheating can soften filament and cause adjacent turns to lightly fuse.

Why “Dehumidified Air” Is A Big Deal For Nylon

In industrial nylon processing, dryers are specified not only by temperature but also by the dew point of the air entering the hopper. One DuPont nylon molding guide calls for very dry air (dew point around −18 °C or lower) during drying, and shows how moisture absorption rises quickly in humid conditions [c].

🧰 Methods And Tools

Tool Comparison For Drying Filament (Real-World Use)
Tool	Temperature Stability	Airflow / Exchange	Capacity	Best For	Watch Outs
Dedicated Filament Dryer	Usually steady	Moderate	1–2 spools typical	Routine drying, printing directly from the box	Some units run hot; verify actual chamber temp with a thermometer.
Food Dehydrator	Good (model-dependent)	Often strong	Often multi-spool with mods	PETG, TPU, nylon, long drying cycles	Height clearance; avoid layouts that block airflow around the coil.
Convection Oven	Varies widely	Strong	High	Big batches when you can control temperature precisely	Temperature swings can soften low-temp filaments; measure with an external probe.
Vacuum / Industrial Dryers	Excellent	Engineered for drying	High	High-value hygroscopic polymers (especially nylon)	Overkill for casual use, but unmatched consistency for sensitive materials.

Oven note: Many home ovens are not accurate at low temperatures. If you use an oven, treat measurement as mandatory, not optional [b].

Dedicated Filament Dryers

Great when you want a single-purpose tool that keeps the filament enclosed.
Works best when the unit has real airflow, not just heat.
Bonus points if you can route filament out while staying sealed.

Food Dehydrators

Often the best balance of stable heat and airflow.
Typically easier to hold mid temperatures for long periods.
If you remove trays to fit a spool, make sure air still circulates around the coil (not only above it).

Oven Drying (When You Can Control It)

Convection mode can help because it mixes air and reduces hot/cold pockets.
Use an external thermometer or probe, and place it near the spool, not on a far wall.
Keep the spool away from direct radiant elements.

🌡️ Temperature Discipline

Two Rules That Save Spools

Do not exceed the material’s recommended drying temperature. Filament can soften, deform, and stick to itself when overheated [b].
Respect the spool. Some spool constructions can loosen or deform when heated; even within safe filament temperatures, the spool design matters [b].

Why “A Little Hotter For Less Time” Can Backfire

Moisture inside the spool doesn’t leave instantly. A hotter blast can soften the outer wraps before the inner wraps have a chance to dry. The result is a spool that feels “dry-ish” on the outside but still prints rough.

Avoid guesswork with low-temperature filaments. If your tool can’t reliably hold the target temperature, choose a different tool rather than “riding the dial.”

🧪 Material Workflows (Practical, Not Magical)

PLA

PLA is often more forgiving than nylon, but it can still pick up enough moisture to cause artifacts.
Use conservative temperatures; long, gentle drying is usually safer than aggressive heat.
Example setting for Prusament PLA: 45 °C for 6 hours [b].

PETG

Moisture commonly shows up as extra stringing and inconsistent extrusion texture.
Example setting for Prusament PETG: 55 °C for 6 hours [b].
If your dryer has strong airflow, PETG tends to respond well to steady drying rather than spikes.

TPU (Flexible Filaments)

TPU can benefit a lot from drying; wet TPU often prints with a rougher surface and “foamy” extrusion.
Example setting for Prusament TPU: 60 °C for 4 hours [b].
Store TPU sealed between prints if you want consistent results.

ABS And ASA

ABS/ASA typically tolerate higher drying temperatures than PLA.
Example setting for Prusament ASA: 80 °C for 4 hours [b].
Drying helps stabilize extrusion and can reduce surface pitting caused by moisture.

Nylon / Polyamide

Think Like A Materials Tech (Just A Little)

Nylon absorbs moisture readily and its behavior can shift as moisture changes.
Industrial nylon guidance focuses on very dry air, controlled temperature, and measured moisture levels [c].
If you print nylon regularly, a tool with controlled airflow (dehydrator or serious dryer) is usually worth it.

PVA / Water-Soluble Supports

These materials can become problematic fast because they love moisture.
Dry them before critical prints and keep them sealed during use.
When in doubt, follow the brand’s own drying profile and keep exposure time to ambient air minimal.

📏 How To Tell It’s Dry Enough

The “Print Behavior” Test

Listen for the nozzle: fewer pops and less hiss is a great sign.
Watch extrusion: the bead should look smoother, with fewer micro-bubbles.
Compare a small calibration print before/after drying using the same g-code.

The “Weight Change” Idea (Simple, Useful)

If you have a decent scale, weighing a spool before and after drying can show whether moisture actually left the material. It won’t tell you the exact moisture percentage, but it gives a real-world signal that drying did something.

Moisture Measurement (If You Want Numbers)

Industrial nylon workflows use instruments for moisture measurement. Teknor Apex describes two categories: gravimetric (loss-by-weight) analyzers and moisture-specific analyzers such as Karl Fischer, noting that moisture-specific methods can avoid confusion from other volatiles and referencing alignment with ASTM D7191 practices [d].

📦 Storage After Drying (So It Stays Dry)

Storage That Actually Works

Use a sealed box or bag and add desiccant. Simple, effective.
Vacuum bags can be surprisingly good, especially for materials that you don’t print daily [b].
If you print directly from a dryer or dry box, keep the filament enclosed from spool to extruder whenever practical.

A nice mental model: drying removes water from the polymer, and storage prevents the polymer from reloading water. Both steps matter.

❓ FAQ

How Long Does It Take For Filament To Get Wet Again After Drying?

It depends on the material family, ambient humidity, and how the spool is stored. Some materials are relatively forgiving, while hygroscopic materials (like many polyamides and water-soluble supports) can start showing print artifacts much sooner if left exposed.

Can I Dry Filament In A Regular Kitchen Oven?

You can, but only if you can control low temperatures reliably and verify them with an external thermometer. Many home ovens fluctuate enough to risk softening low-temperature filaments, so careful measurement is the difference between “works” and “ruins a spool.”

Why Does Wet Filament Pop Or Hiss While Printing?

Moisture trapped in the filament turns into steam inside the hotend. That expanding vapor forms bubbles in the melt, which can cause popping sounds, surface pitting, and inconsistent extrusion.

Is A Food Dehydrator Better Than A Filament Dryer Box?

Often, yes for raw drying performance. Many dehydrators provide steady heat and strong airflow, which helps moisture leave the coil evenly. A filament dryer box can still be great for convenience, especially if you print directly from it.

Do I Need Special Tools To “Measure” Moisture?

Not for everyday printing. Print behavior and a simple before/after weight check can be enough. If you work with nylon frequently and want moisture numbers, industrial workflows use analyzers (including moisture-specific methods such as Karl Fischer) to avoid ambiguity [d].