Drying filament and desiccant

I was chatting with some other 3D printing geeks earlier, and the topic of wet filament came up. It’s a funny topic in the 3D printing world. Some people think it is never a problem, while others believe drying filament is essential for quality prints. I fall somewhere between the two.

An example of dehydrating saving the day

Tree printed after filament was dehydrated.

I can give an example of when drying filament is important Recently I had a roll of white PETG from Sunlu. I’ve printed this stuff quite often with no problems. But this latest roll was different. I could hear popping almost right away when I started printing. My first layer was also looking like crap and had stringing. I took the PETG out and put it in the dehydrador. Two hours later I tried again. The picture on the right is the print I did after dehydrating (I forgot to take a picture of the bad print). The print looks fine and there were no strings present.

The filament probably didn’t get wet at my house.

Most likely, the filament in question became wet during shipment. I used to work for one of the package shipment companies and have seen first hand what these packages go through. Amazingly, we don’t have more problems due to how things are shipped. I bring this up because often people say they live in a relatively dry climate, so they never need to dehydrate filament. Unless you can always be assured of getting dry filament to your house, then chances are you will eventually deal with damp filament.

I’ve also had problems with filament samples I get from various places being wet upon arrival. That has been particularly true for nylon samples. Wow, that stuff gets wet fast!

The dehydrator I use

Dehydrating some desiccant.

Currently, I use a Rosewill food dehydrator I bought off of Amazon. I cut the insides out of three shelves to easily put a 1k roll of filament in there. I left two shelves intact so that I could use the dehydrator for desiccant packs as well. The picture below shows the dehydrator with desiccant loaded up.

The first dehydrator I used was a disaster. I had some filament melt after only an hour in the dehydrator. At first, I thought I chose too high of a temp. But after testing the dehydrator, I found out it was heating in a range and would go from up to about 15C over the set temp to 15C under the set temp. Going 15C over was a disaster.

With this new dehydrator, I did some testing. It generally keeps within a few degrees of the set temp. During testing, I never saw it go more than 4C over the set temp.

The temps and times I use

Below is a table of temps and times I’ve been using. I don’t remember where I got this originally. But I know I’ve slightly adjusted it over time as I gained more experience drying out the filament. These temps are all in Celcius. If anyone uses my temps and times, I would keep an eye on your dehydrator just in case. You can tell if it is too hot because the filament will start to warp. If that happens, your likely drying at too hot of a temp.

Before drying a filament, I check out the manufacturer’s website to see if they have a recommended temp for drying. Most don’t, but I’ve seen a few that do. If nothing else, they may publish the glass transition point of the filament. No matter what, you need to make sure to stay below the glass transition point, or you will ruin your filament.

FilamentDurationTemperature
PLA2-4 hours45C
PETG2 hours65C
ABS2 hours60C
Nylon6-12 hours70C
ASA3-4 hours60C
Desiccant2 hours80C
Times and temps I use to dehydrate filament.

Again, the above times and temps are what I’ve used successfully. Depending on the dehydrator you use and the type of filament, the times and temps may vary.

My use of desiccant

When a roll of filament is not in use, I keep it in a ziplock baggie with a desiccant packet. I haven’t had enough problems with wet filament to look at other solutions. The baggies seem to work fine for me. Whenever I use a filament roll, I put the desiccant pack in a container to dehydrate later. I always make sure to use a dehydrated desiccant pack each time I put filament away. The container that came with the desiccant works great to store the packs after being dehydrated.

I don’t dehydrate most of my filament.

I don’t normally dehydrate my filament. Usually, I only use the dehydrator if there is a reason. The example above was an obvious one. But I’ve also dehydrated filament when I get strings I can’t get figured out. Sometimes wet filament is the cause of those strings. I would say that most of the filament I’ve dried comes from samples I get and don’t print right.

Song of the day: High ‘N’ Dry

Ok, this is a different kind of dry. But this Def Leppard song rocks!

Bonus Song: Saguaro

If you live in a dry desert, filament moisture probably won’t be a huge issue. Which leads into this track from Hacienda Brothers.

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