Most filaments come in a vacuum sealed bag to keep out moisture. If you have many rolls of filament, some not yet used, it is best to keep them in their sealed bags until ready for use. That said, once open there is a possibility for them to begin absorbing moisture from the air.
The amount of water that the plastic will absorb depends on the type of plastic, and the humidity in your area. In my experience Nylon has the most issue absorbing moisture, followed by ABS. I haven't really had issues with moisture in PLA, but it can be an issue for some people. As I understand PETG is one of the least susceptible to moisture, and one of many the reasons I prefer to print with it.
Filament that has absorbed moisture can exhibit bubbling/popping noises from your heated nozzle as the water turns to steam. You may even be able to see little puffs of steam. This bubbling can adversely affect your print quality, leaving a rough surface finish, poor interlayer adhesion, and reduced part strength.
To restore rolls of filament that have absorbed moisture, or to avoid that absorption in the first place, we can make an airtight chamber filled with dessicant to store our filament in.
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This setup consists of 3 parts.
- 5 Gallon Bucket - This will be our chamber, holding filament and dessicant.
- Gamma Seal Lid - This product converts a 5 Gal bucket into an airtight container with a convenient screw-on lid. If you've ever struggled with hammering on or crowbar-ing off a typical 5 gal lid, this is the opposite of that. It has a bottom adapter ring that snaps onto the top of a standard 5 gal bucket; this ring provides threads which the lid then screws down onto. The lid has a large O-ring seal around the perimeter that keeps it air tight.
- Renewable Mini Dehumidifier - You've probably seen little bags of silica gel included with filament or electronics produces saying "DO NOT EAT". But besides being inedible, did you know that silica gel is also re-usable? Just apply heat to drive off moisture and silica gel can be reused countless times. This unit contains about 1lb of silica gel and a built in heating element. Under normal operation it just sits wherever you want to absorb moisture. When it becomes saturated and you want to renew it, plug it in to a wall socket for 8-10hrs and the heater drives off the moisture (do this in some area where the extra moisture is not as issue, not in the same spot you are trying to dry out!).
There's really not much to do besides put them all together. Snap the adapter ring onto your bucket. Drop the dehumidifier in, and fill with rolls of filament. I was able to fit 4 1kg rolls, and 3 1/2kg rolls all at the same time.
The dehumidifier has a small window with color-indicating silica beads. These change to purple/pink when saturated, which means time to plug it in and renew it. I also like to monitor how much water is absorbed by weighing it before putting in the bucket, then every few days or so. You can get an idea of if it is continuing to absorb moisture or when it has pretty much gotten all of it!