How to Dry Filament: 3 Easy Fixes For Wet Plastic

All FDM filaments are hygroscopic, meaning they absorb airborne moisture. 

Moisture absorbed by 3d printer filament can lead to problems such as inconsistent extrusion, nozzle clogging, and poor surface quality. This article explores how to dry filament for optimal performance.

The techniques work on all types of filament, including PLA, ABS, PETG, and Nylon.

To determine if your filament needs drying, simply heat the nozzle on your 3D printer and extrude about 100mm. If you hear popping sounds or see steam released, it’s time to dry your filament.

There are several methods for drying filaments, and we’ll focus on practical and safe techniques that you can easily implement at home.

Signs of Wet Filament

All filament materials used in FDM 3D printing are hygroscopic. And even with proper storage, you’re filament may absorb some moisture—wet filament results in lower print quality.

Here are some tell-tale signs that your filament has absorbed moisture and may need to be dried:

• Popping/Cracking sounds: One of the most apparent indications of wet filament is hearing popping or cracking sounds when extruding. When the water inside the filament rapidly boils due to the hot extruder, the steam escapes creating the sounds you hear.
• Sizzling sounds: Similar to the popping sounds, sizzling noises during extrusion can also suggest that your filament contains moisture. The sizzling occurs when water trapped in the filament turns into steam and tries to find its way out.
• Inconsistent extrusion: Wet filament may lead to uneven extrusion lines. The moisture can cause the filament to swell and change diameter, resulting in an inconsistent material flow during the print.
• Stringing: The extrusion may produce stringing between gaps in your print when moisture is present in the filament. If you notice thin strands of plastic stretching between different parts of your print, creating a messy, unappealing finish, you may have a moisture problem.
• Brittleness: Noticing that your filament becomes brittle before or after printing can be a sign of moisture absorption.
• Layer lines: Wet filament can reduce layer adhesion and impair part strength. Moisture can cause the melted filament to cool rapidly and create poor interlayer bonding. You’ll notice it as visible layer lines or layers peeling apart in a finished print.

Now that you’re familiar with the signs of wet filament, it’s essential to take the proper steps to dry it out and prevent the associated printing problems.

The rate of moisture absorption depends on the filament materials.

Some of the most hygroscopic materials, like PETG and nylon, may have issues after just 24 hours out of storage.

We’ll cover storage methods later, but storing your filaments in a dry and cool place is best. Airtight containers with desiccants can help minimize the risk of moisture absorption.

How to Dry Filament

1. Using a Filament Dryer

Dedicated filament dryers are the best and safest method to remove moisture from your 3D printing filaments. They’re purpose-built for drying rolls of filament.

There are several designs, but they usually have adjustable temperature settings and built-in thermostats. Place your filament spool inside the dryer, set the appropriate temperature according to the filament type, and leave it to dry.

Filament dryers use heat to promote evaporation and remove moisture from the filament.

Depending on the model, you can dry by material type or set a timer.

If you’re looking for a good filament dryer, we recommend the upgraded Sunlu filament dryer (Amazon). They also have a lower-priced model (Amazon) that does the trick but doesn’t have advanced features like timed drying.

2. Using a Food Dehydrator

Food dehydrators are an effective method to dry your filament.

They work by circulating hot air around the filament, promoting evaporation during the filament.

To use a food dehydrator for drying filaments, ensure that it has adjustable temperature settings and enough space to accommodate your filament spool.

Place the spool of filament on the dehydrator tray and set the temperature according to the filament’s material. Here are our recommended drying temperatures:

• PLA: 40 °C for 4-5 hours
• ABS: 70 °C for 2-6 hours
• PETG: 70 °C for 4-6 hours
• Nylon: 80 °C for 4-6 hours
• TPU: 60 °C for 4-5 hours

You can get a cheap food dehydrator on amazon.

3. Using an Oven

Drying the filament in an oven is another option, but it requires more caution due to the higher temperatures and potential for damaging the filament.

First, preheat the oven to the correct temperature. Use the temperatures below as a general guideline based on your filament:

• PLA: 40 °C for 4-5 hours
• ABS: 70 °C for 2-6 hours
• PETG: 70 °C for 4-6 hours
• Nylon: 80 °C for 4-6 hours
• TPU: 60 °C for 4-5 hours

Once the oven has preheated, place the spool on a baking sheet and closely monitor the process to prevent overheating or melting of the filament.

It’s crucial to check that the oven temperature matches the temperature reading on the thermometer.

Many ovens overheat during the preheating process, which is why waiting for the oven to preheat before placing your spool on the racks is essential.

For additional safety, we recommend using a thermometer to check the actual inside temperature, as the oven thermostats aren’t always accurate. If the oven temperature is slightly higher than the desired drying temperature, the plastic could soften, making your filament unusable.

Some filaments, like ABS, give off an unpleasant odor and fumes. It’s something to remember if you plan to use the oven for cooking food. For this reason and the potential fire risk, we don’t recommend using a range if you can access a filament dryer or food dehydrator.

Proper Storage & Prevention

Proper storage of your dry 3D printer filament can go a long way in preventing filament moisture issues. By understanding and implementing the appropriate storage solutions, you will run into fewer problems caused by moisture.

Firstly, consider using airtight containers or zip-sealed bags for storing filament rolls.

Place your filament in a dry and cool area away from direct sunlight when storing it. Extreme temperatures and high humidity levels can impact its performance.

Consider using desiccants to eliminate airborne moisture further.

Desiccants absorb moisture in the container or bag, preventing it from affecting your filament.

Some popular desiccants include silica gel packets and clay sachets. Add a few of these to your storage container, and remember to replace them regularly to maintain their effectiveness.

Here are a few additional tips to keep your filament dry and in good condition:

• Always reseal your storage bags or containers immediately after use to minimize exposure to air and moisture.
• Label your filament rolls with the opening date so you know how long they’ve been exposed to air.
• Consider using a filament storage box with built-in desiccants for added convenience and protection.

By following these guidelines and investing in proper storage solutions for your filament, you can significantly reduce the need to dry your filament and ensure a smoother 3D printing experience.

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