How to Dry Wet Filament: The Complete Guide

Why Filament Absorbs Moisture

Most 3D printing filaments are hygroscopic — they absorb moisture from the air. This isn't a matter of "if" but "when." Even in relatively dry climates like Utah, an unsealed spool left out for a few weeks will absorb enough moisture to noticeably affect print quality. Nylon absorbs the fastest, followed by PETG, TPU, and PLA. Even PLA, which people assume is immune, degrades when wet.

Symptoms of Wet Filament

Before you start drying, confirm moisture is actually your problem. Here are the telltale signs:

• Popping or crackling sounds: The most obvious symptom. You'll hear small pops as moisture turns to steam inside the hot end.
• Excessive stringing: Wet filament oozes more, creating strings and wisps between features.
• Rough, bubbly surface: Steam escaping creates small bumps and an uneven texture on print surfaces.
• Poor layer adhesion: Moisture disrupts the bonding between layers, making prints weaker.
• Dimensional inaccuracy: Steam expansion causes inconsistent extrusion, leading to dimensional variation.
• Brittle filament: Some materials, especially PLA, become brittle when they've absorbed moisture over time.

Drying Methods

Dedicated Filament Dryer

The best option for most people. Filament dryers like the Sunlu S2 or eSun eBox are purpose-built with the right temperature range, a spool holder, and even a filament feed port so you can print directly from the dryer. They cost $40–$80 and are a worthwhile investment if you print regularly.

• Set-and-forget operation
• Consistent, controlled temperature
• No risk of melting your filament
• Can dry while printing

Kitchen Oven

An oven works but requires caution. Most kitchen ovens have poor temperature accuracy at low settings and can have hot spots. If your oven runs even 10°C too hot, you'll melt PLA into a solid blob. Use an oven thermometer to verify actual temperature, and never leave filament unattended in an oven.

Warning: Do not use a food oven for materials like ABS that off-gas when heated. Use a dedicated dryer or a secondary oven for those materials.

Food Dehydrator

A budget-friendly alternative. Many dehydrators reach the temperatures needed for PLA and PETG. You may need to modify the trays to fit a spool. Temperature control is usually limited, so verify it can reach the required range for your material.

Drying Temperatures and Times

Getting the temperature right is critical. Too low and you're wasting time. Too high and you'll deform or fuse the filament on the spool.

• PLA: 45–50°C for 4–6 hours
• PETG: 65°C for 4–6 hours
• ABS: 65–70°C for 4 hours
• ASA: 65–70°C for 4 hours
• TPU: 50–55°C for 5–8 hours
• Nylon: 70–80°C for 8–12 hours
• Polycarbonate: 80°C for 8–12 hours

These are starting points. Severely waterlogged spools may need longer. If you still hear popping after the recommended time, continue drying in 2-hour increments.

Prevention: Keeping Filament Dry

Sealed Storage

The single best thing you can do is store filament in airtight containers with desiccant. Large plastic bins with gasket lids work well. Vacuum bags are even better for long-term storage. Replace or regenerate desiccant regularly — color-indicating silica gel makes this easy.

Climate Considerations

Utah's low humidity helps, but it's not a free pass. Indoor humidity from cooking, showers, and humidifiers still affects filament. A hygrometer in your printing area helps you monitor conditions. Aim for below 30% relative humidity in your storage containers.

Print from a Dry Box

For critical prints or hygroscopic materials like Nylon and TPU, feed filament directly from a sealed dry box with desiccant. This is the gold standard for moisture-sensitive materials.

We Can Help

If you're dealing with filament moisture issues, bring your spool into Forgely Roy. We can test your filament, advise on the best drying approach, and stock dedicated filament dryers and desiccant supplies. We also carry fresh, factory-sealed filament in every material type — so if your spool is too far gone, we'll get you a fresh one.

📍 Forgely Roy — 5519 S 1900 W, Roy, UT 84067
📞 385-449-2694
⏰ Mon–Fri 11–6 • Sat 11–3