When should you dry filament and how do you do it?
All filaments absorb moisture from the air; some in just a few hours. Drying is the most effective maintenance task for the time it takes.
What the failure looks like
Popping sounds and bubbles during extrusion, visible steam, rough surface finish, severe stringing, and parts that snap easily.
Causes, most likely first
- 01
Open-air storage
A spool left open on a shelf will absorb moisture in a few weeks.
- 02
Hygroscopic materials
Nylon, TPU and PETG absorb moisture much faster than PLA.
- 03
Humid environment
In coastal areas, this is an ongoing issue.
Step-by-step fix
1. Identify moisture
Extrude into thin air: if it crackles, emits steam or the strand has bubbles, there is water present.
2. Choose temperature and time
See table. The rule of thumb is 10-15 °C below the softening temperature of the material.
3. Use a filament dryer or a dehydrator
A food dehydrator is the best cheap solution for this. An oven works fine if you use a separate thermometer.
4. Print directly from the dryer
For highly hygroscopic materials, print with the spool inside and the strand exiting through the side.
5. Store it properly afterwards
Airtight bag with indicating silica gel; it can be regenerated in the dryer itself.
| Material | Temperature | Time | Absorption rate |
|---|---|---|---|
| PLA | 45-50 °C | 4-6 h | Slow |
| PETG | 60-65 °C | 4-6 h | Medium |
| ABS / ASA | 70-80 °C | 4 h | Low |
| TPU | 50-55 °C | 6-8 h | High |
| Nylon (PA) | 70-80 °C | 8-12 h | Very high |
So it doesn't happen again
- Airtight bag + silica gel for any spool not currently on the machine.
- Indicating silica gel (colour-changing) to know when to regenerate it.
Related questions
Does the silica gel from shoe boxes work?
It helps, but it is almost always saturated. Buy indicating silica gel and regenerate it in the oven or dryer.
Can over-drying ruin the filament?
Exceeding the recommended temperature will: the spool deforms and the windings fuse together. Stick to the table.
Keep reading
What if it isn't worth your time?
Sometimes the part is more urgent than the learning curve. We're a workshop in Viladecavalls: send us the file and we'll print it with the right material and settings.
Still not working?
Tell Marco which printer and material you use and he'll tell you what to change.
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