Recover bad filament for better 3D Printing

When you use the same filament but get different results on the same gcode, you probably have moisture in your filament.

We often don’t think about filament being the issue when we help each other dial in a 3D Printer. Its mostly talks about adjusting settings, temperatures, types of material and etc.

Not often are we talking about what can happen to your filament if you leave it hanging on the machine while you troubleshoot other issues.

I’m talking specifically about moisture buildup in filament.

Notice the red areas in the dry and moist filament!

Moisture affecting your filament

A lot of printing issues are actually due to bad filament caused by moisture. What happens is that your filament absorbs moisture over time when left opened in a room or inside the 3D printer.

The moisture will then boil inside the 3D printer and when moist turns into steam it expand, causing expansion inside the hot-end and push filament out at a higher than intended rate.

This unintended extrusion leads to 3D prints looking blurry with a lot of stringing.

What’s causing the moisture to build up?

Different material types (like ABS, PETG, PLA and Nylon) are somewhat hygroscopic and will absorb water molecules into the material.

Basically they are absorbing moisture from the air.

In this article I try to somewhat scientifically test different materials and how they behave after printing.

How to fix moisture in bad filament

When it comes to fixing the bad filament caused by moisture it’s more or less one thing you can do. Dry the filament!

There are many ways of doing this, and in the video above I go through them in detail.

Basically having a modified fruit dryer is the best option as it allows you to set a exact temperature (depending on what material you’re drying) and have it on for a long time.

Usually you need to modify the fruit dryer and remove all but the lowest shelf. Then load up your spool and start drying!

Drying procedure

Depending on material you want to adjust temperatures in the dryer. Here’s a list of different drying temperatures of different materials. These are generalisations.

  • PLA – 30-40°C
  • ABS: 50-60°C
  • TPU: 40°C
  • PETG: 40°C
  • Nylon: 60-70°C
  • PVA: 40-50°C

Note that specially some “professional” PLA filaments might actually harden if you dry them at too high temperature, so always be more carefull with PLA.

Luckily PLA usually absorbs very little (or none) moisture.

Hopefully this helps you recover bad filament and get 3D Printing again!

Let me know if you have any questions or ideas!

About The Author
- 3D-visionary enthusiast exploring the world of 3D-printing.With 12+ years of 3D experience from visualization, VFX and CAD-design and the industry itself, I tend to find interest and ideas from the world around me.

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