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Fragile: Keep Dry

How to Dry Filament: PLA, ABS and Nylon

Picture of Hironori Kondo
by Hironori Kondo
Nov 2, 2018

Moisture from the air can easily ruin your 3D printer filament, meaning it can also ruin your prints! Here's how to save a wet spool.

How to Dry Filament Filament vs Moisture

Plastic polymers are hygroscopic.
Plastic polymers are hygroscopic. Source: 3devo

All FDM 3D printing filaments are hygroscopic. That’s a fancy way of saying that the material likes to absorb moisture.

This hygroscopicity can wreak havoc on 3D printing filaments. As plastic polymers, they’re made of chains of molecules strung together. Moisture introduces water molecules that break up these chains, ruining the plastic and causing a whole slew of problems while printing.

But don’t fret. “Wet” spools of filament are easily saved, and proper storage can prevent future mishaps.

In the following, we look at how to identify wet filament, how to dry it, and finally, how to store the moisture-free result.

How to Dry Filament Identifying Wet Filament

"Fuzzy" surfaces are a sign of wet filament. Source: Matterhackers

Different filaments absorb moisture at different rates, but there are a few common signs that you’ve got a wet spool:

  • Popping/cracking sounds when extruding
  • Severely reduced part strength and layer adhesion
  • Uneven extrusion lines
  • Uncharacteristically severe stringing, blobbing, or oozing
  • Uncharacteristically textured or “fuzzy” surfaces on prints

If you’re seeing any of the above symptoms, it’s probably a good idea to dry out your filament. With especially hygroscopic materials like nylon, PETG, PVA, and flexibles, symptoms may appear after just one night left out in the open.

Dry out wet filament as soon as you identify it to preserve print strength and quality.

How to Dry Filament Method #1: Use an Oven

Oven-drying filament.
Oven-drying filament. Source: Thomas Sanladerer

Probably the easiest and most common way of drying filament is throwing it in the oven. Just set the temperature to right below the glass transition temperature of the plastic, and leave it in there for 4-6 hours for the moisture to cook out. The longer you leave it, the more drying you’ll get.

  • PLA: ~40-45°C
  • ABS: ~80°C
  • Nylon: ~80°C

Important note: Wait until your oven reaches the target temperature before placing the spool in. All ovens slightly overshoot the target temperature when heating up, so placing your spool in early may soften the plastic and fuse parts of the filament together.

You also want to make sure that your oven is capable of accurately holding the temperatures listed above. If not, you run the risk of melting all the plastic and fusing your entire spool together.

How to Dry Filament Method #2: Use a Food Dehydrator

Food dehydrators are great for drying filament.
Food dehydrators are great for drying filament. Source: Proctor Silex

Food dehydrators are also great tools for drying out filament, especially if you don’t have a nice oven. Originally designed for drying fruit, dehydrators are designed to operate at lower temperatures than ovens and are therefore easily repurposed for drying filament.

  • PLA: ~40-45°C
  • ABS: ~80°C (or highest available temperature)
  • Nylon: ~80°C (or highest available temperature)

At low prices, they can be found all over the Internet. Usually, they come with removable layers and meshing that you can add or remove to fit your spools.

How to Dry Filament Proper Storage of Dry Filament

Store filament away from moisture.
Store filament away from moisture. Source: SpannerHands / Thingiverse

Now that your filament is dry, you’ll want to keep it that way for as long as possible. To do that, store dry spools in a humidity-controlled environment. This can range anywhere from an airtight box with desiccant packs to dedicated commercial solutions. Usually, the former is more than enough, but use what suits your needs.

Just keep in mind that proper storage can’t dry filament for you — it can only preserve it. If your filament becomes wet again, you’ll have to re-dry it with the methods described above.

How to Dry Filament Final Thoughts

Get printing!
Get printing! Source: Ultimaker

Hopefully, this guide was helpful for learning how to identify and dry wet filament. It’s great knowledge to have, especially when printing expensive, specialty materials. And, in general, it should help to drastically reduce print failures.

For even more drying options, check out our article on filament dryers. Or, for more information on filaments, take a look at our extensive 2018 3D Printer Filament Guide.

Happy printing!

License: The text of "How to Dry Filament: PLA, ABS and Nylon" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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