Dehydrating your filament: Moisture in 3D printing filament, and how to avoid it

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We’ve all been there before: starting up a print after a few weeks’ break from printing, only to realize something changed and your prints seem …. just bad. What could possibly cause such a decline in print quality? 

Usually, the culprit is moisture. Most 3d printing filaments are hygroscopic (the filament loves to absorb moisture), and many, such as PETG, are incredibly hygroscopic. This leads to the filament absorbing a significant amount of moisture, and thus causing the decline in print quality you may observe. In order to solve this, we need to dry the filament.

Stringing happens when your filament isn't dry!
One of the main symptoms of wet filament – filament stringing

“Wet” filament can cause many issues, such as stringing, poor print quality, and a much rougher surface finish. If the amount of moisture in the filament is great enough, there may be bubbles inside the filament that will cause uneven extrusion. This is bad, because it can make prints weaker and overall, make your printing experience worse. Now, you may be wondering, is there anything that can be done about this?

What can be done to remove moisture?

There are ways to dehydrate your filament, getting rid of moisture and bringing the filament back from a near unusable state. I’m going to split these methods into two categories: passive dehydration, which includes storage techniques and ways of keeping filament dry. However, if your filament is already “wet”, I’m also going to cover active dehydration, which includes ways of removing moisture already present in filament.

Passive Dehydration

In this section, I’m going to cover storage techniques you can use to store your filament and keep it from going bad in the first place.

  1. Airtight storage with desiccant

This is the easiest way of keeping your filament dry. Simply using airtight storage bins can make a huge difference in long-term storage. Personally, I bought some pet food holders, as they have a big storage volume and wheels, so I can easily transport all my filament at once if necessary. I also bought rechargeable desiccant for these airtight containers. I chose an 8lb jug of desiccant beads, which I poured into my airtight container. This absorbs moisture before the filament does.

This is my favorite airtight storage option. It’s marketed towards food storage, but it works perfectly with desiccant beads and filament.

  1. Vacuum seal bags

This is the ideal option if you’re trying to store specific filament spools for long period of time. This solution is foolproof, however it is more difficult to initially store and access your filaments. You’ve probably seen this done before, usually by the manufacturer before they ship out the filament. You can purchase reusable vacuum sealed bags on Amazon, which will provide you with a good amount of long-term filament storage.

Active Dehydration

What if your filament has already absorbed moisture, and you need to get rid of it? Luckily, there are ways of removing moisture from your filament. The best way of doing this is to purchase a filament dehydrator on a website like Amazon. Personally, I use the EIBOS Cyclops 3d printing filament dryer, which works incredibly well and can dehydrate two spools of filament at once. However, the choice is up to you. I have linked many filament dehydrators below, as well as the one that I use, for you to compare and contrast and determine which is the best for your needs. If you don’t want to purchase a filament dehydrator, you can use your oven or even your own print bed to dehydrate filament, however this method is less fool-proof and buying a dedicated filament dryer is best.

Buy the EIBOS Cyclops!

Overall, dehydrating filament is essential to achieve good print quality, and avoid common issues such as stringing. This is stuff I had to painstakingly learn with trial and error during my first year 3D printing. I hope you’ve learned a lot from this blog post so you can avoid the mistakes I made storing filament.