All FDM 3D printing filaments are hygroscopic. What does that mean? Well, it just means that all filament material absorbs moisture over time. This moisture can ruin 3D printing filaments and as a result, your prints. Plastic polymers are made of chains of molecules tied together. Hygroscopic means that moisture introduces water molecules in between these chains, breaking the structure and ruining the plastic. This can cause a host of problems during printing.
Is there a solution to this problem? Why yes there is! Spools that have sat for a while, not properly stored, and have absorbed moisture can be dried. Filament can be dried in the oven, modified food dehydrators or in specially designed filament dyers like the ones from PrintDry. To prevent/lessen the need for this, opened filament should be stored in sealed containers with desiccant. I like the desiccant pouches that can be recharged like the Wisedry brand available on Amazon. They are not that expensive and shipping times are reasonable.
So, now that we have discuss hygroscopic, does this mean that all filament that has sat out is useless unless dried? I didn’t really know the answer to this until I tested it. I had a couple different spools of filament that have been sitting on shelves for roughly two years, not properly stored. That’s two years of absorbing moisture and breaking those chains. Based on common theory, that filament should be garbage and should either be dried for hours or just tossed. Well, I decided to run some test prints by printing some Among Us characters and since it’s Halloween, a vase Skull. The first test filament was some old Flashforge PLA that came with an Adventurer 3. As you can see from the prints above, the prints came out rather nice. If you look closely, especially with the Among Us print, you can see that there are some surface imperfections that could be due to moisture but overall, not a bad print. The skull came out great!
The second print was using Hatchbox PLA in Cool Gray, my favorite filament. I stock a ton of this stuff and usually have a few half rolls sitting around. This roll had been sitting on a shelf for a long time, untouched. I loaded it into one of my Ender 3 machines and printed a Mandalorian right thigh armor. My son and I are working on a full Mandalorian cosplay costume! As you can see from the photo, it is printing really well.
So, I didn’t do this test or right this post to imply that moisture isn’t a problem or that you shouldn’t store your filament in a sealed container with desiccant. Afterall, I have experienced “wet” filament and had prints fail because of it. I just wanted to see if I accidentally left a filament out, unprotected from the elements, could I use this in a pinch without spending hours drying it ahead of time.
Well the answer seems to be yes. At least for old FlashForge and Hatchbox filament. Make’s one think…are there filament manufacturers who’s product is less affected by moisture than others?
Thanks and happy printing!