As a 3D printing enthusiast, a wet filament is the biggest threat to your creativity (and wallet). I’m pretty sure you’ll be careful not to spill your drinks on your spools. But what you should be worrying about is the humidity in the air. That’s why we need to have this quick discussion on how you should store 3D printing filaments.
And if you need any help with choosing 3D filaments, check out our 3D filament buying guide.
Why 3D Printing Filament Storage Matters
Fused Deposition Modelling (FDM) filaments are plastic-based. So, what’s all this fuss about proper filament storage? Well, the thing with most filaments, particularly Nylon, PVA, PETG, ABS, and the oh-so-popular PLA, is that they are hygroscopic. This means that they readily absorb water droplets from the air to become ‘wet.’
The filament doesn’t get ‘soggy’ as you’d expect. On the contrary, it gets brittle to the point that it breaks even before you load it onto the machine.
This poor quality is also transferred to your printed objects. When you try printing with a ‘wet’ filament, the water is heated into steam, causing the filament to bubble during extrusion. These bubbles end up on your print’s surface, causing blemishes, inconsistency, and weakness.
Note that as the filament absorbs moisture, it also tends to swell, and this causes irregular diameter across the spool. This diameter augmentation affects the flow rate during extrusion leading to extruder jams and irregular gaps between individual extrusions. This causes poor surface quality or, put simply, failed prints.
How Long Can You Leave PLA Filament Out?
I believe the biggest determinant here will be the humidity level in your printing station and your region.
Generally, the higher the humidity, the higher the filament’s moisture absorption rate will be. It’s important to note that the absorption rate also varies between brands and between spools (from the same manufacturer).
I’ve had filaments that started breaking in the printer after sitting out for around 3 days. I’ve also heard of makers who’ve had no problems printing with filaments that have been out for several months and even a year. If you’re actively printing, I don’t think leaving your PLA filament out for a day or two would pose any major problems. But depending on the humidity level in your home, you may want to consider an effective storage system.
Is it OK to Leave Filament in My 3D Printer?
I don’t think this is a problem if you have a way of protecting the filament from absorbing too much moisture. Again, this will depend on the humidity level in your studio and how long you intend to leave the filament in the 3D printer. One thing that’s for sure is that removing a broken piece of filament in the Bowden tube can be painstaking. If you aren’t printing for some days, you’re better off storing the filament safely.
How Do You Store 3D Printer Filament?
There are three major ways of storing 3D printing filaments at your disposal:
1. Dehumidifying Dry Boxes
These are advanced drying boxes that are engineered purposely for keeping 3D printing filaments dry. Although these boxes vary slightly in design, pretty much all of them have drying capabilities, a digital hygrometer, and a temperature indicator. Most of them also have ball-bearing rollers that allow you to feed the filament into the printer while still in the storage.
When purchasing a 3D printing filament storage box, you’ll first need to consider its capacity. How many spools can it accommodate at once? For instance, the Sunlo Dry Box accommodates a single 1-kg spool of filament at a time. On the other hand, the Polymaker Polybox can accommodate two 1kg spools, one 2kg spool, 1kg and 2kg spools together, or one 3kg spool. Both of these dry boxes are a solid buy, it just depends on your needs or preference.
Secondly, you need to consider how the drying box lowers the humidity. Some units have a heating unit and will allow you to preset the desired temperature range and heating time. However, others use desiccant pouches to absorb moisture in place of a heating element. For professional printing, you’ll need a separate dehydrator to accompany non-heating drying boxes.
The Sunlo Drybox
The Polymaker Polybox
2. Dehumidifying Dry Cabinets
Dehumidifying cabinets are another excellent option for 3D printing filament storage. These are tightly sealed storage units with a built-in humidity control unit. They are used for storing Moisture Sensitive Devices (MSD) and items, including cameras, lenses, telescopes, binoculars, photographs, and even coffee.
If these cabinets can be used for all the above electronics and items, they can also be safely used to store 3D printing filaments. They are notably pricey. The smallest units (around 30L) will cost you around $150 on Amazon – check out dehumidifying dry cabinets on Amazon. On the upside, there won’t be consumable parts to worry about or desiccants to replace.
Most of the dehumidifying cabinets on Amazon are designed particularly for electronics and camera gear. Although they can also be repurposed for filaments, there is no way to print with the filament while drying. But some brands have started developing filament-oriented dehumidifying cabinets. One such brand is Eureka Dry Tech. I’ve not yet interacted with its products, but I believe they are worth checking out.
3. Vacuum Bags
If a dehumidifying box or cabinet isn’t so necessary for your printing needs, then these vacuum bags may be just what you need. The best plastic 3D printer filament storage bags are relatively inexpensive and easy to use. Most of them cost $15-$20 for a pack of 5-10 storage bags.
Most of them have a straw through which you suck the air out. Some cool brands will go the extra mile to include an exhaust pump, so you don’t have to use your mouth. These 3D filament storage bags also come with desiccant packets and humidity indicator cards to keep the humidity levels in check.
As a 3D printing enthusiast or professional, the quality of your prints will depend not only on your expertise in the machine, but how you store your printing materials. Mind you, you don’t have to invest in a premium dehumidifying cabinet or dry box if your budget doesn’t allow it. There’s also an option to build a DIY filament dry box if you’re feeling crafty. All you’ll need is a plastic box with an airtight seal (should be big enough to hold your spools) and a bag of rechargeable silica gels. This might not be the most effective 3D printing filament storage method. But it will certainly help if you don’t intend to store a lot of filament.