How to Store Your 3D Printing Filament Properly

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There are a lot of issues and natural factors that you need to contend with as 3D printing professional, but none of it is probably more intrinsic to the environment as humidity. Why would such a naturally-occurring phenomenon be a problem? It all comes down to how humidity affects filament performance, which is why proper care and storage of your filament is a very important practice. In this article, we list down the best and most reliable methods to store your 3D printing filament.

Why do I need to store my filament?

Most 3D printing filament materials have this peculiar characteristic of being hygroscopic, meaning they tend to absorb moisture from the environment. While different hygroscopic materials also have different mechanisms that promote moisture uptake, polymers (such as the materials that filaments are made with) are especially prone due to their long-chain structures. Along the chain of these polymers are “polar” or charged segments, to which water molecules in the air readily bond to.

Of the common filament materials, PLA and nylon are especially notorious for being very hygroscopic. However, all materials used in 3D printing need to be stored deliberately to avoid the effects of moisture pickup.

Consequences of a poor filament storage

To emphasize how important proper filament storage is, these are the possible problems you can encounter when you neglect proper storage practice.

1. Filament degradation

Prolonged interaction of the filament material with moisture leads to a reaction known as hydrolysis. This process breaks down some of the bonds that constitute long-chain polymers, resulting in increase brittleness. For 3D printing filaments, the loss of flexibility can be especially problematic considering the convoluted path that these filaments take from the spool to the extruder. Having your filament breaking apart in the middle of the printing process will result in a ruined print and will require that you spend a lot of time cleaning out your extruder setup.

2. Sputtering during printing

The most common sign of a filament that has been stored poorly is sputtering, bubbling, or hissing during printing. This happens as the trapped moisture in the filament heats up along with the rest of the filament material, eventually resulting in vapor formation. This can happen just as the filament leaves the hot end or even after the filament has already been laid down on the build platform. How this affects the quality of your print is unpredictable, but we’re pretty sure it’s not going to do favors to your print’s durability and overall finish.

3. Nozzle blockage

This is probably the worst consequence of a poorly stored filament. Related to the issue of sputtering, a trapped bubble of vapor in the filament can expand as the filament gets heated. This can lead to the filament “swelling” inside the extruder setup. In a worst-case scenario, this can happen right before the filament enters the nozzle. The accumulation of filament material right at the nozzle can easily block it. This means stopping the print, disassembling your nozzle, and cleaning it out. In other words, it will be a huge headache.

Filament storage options

Knowing how problematic it can be when you don’t store your filament properly, it’s time to determine your best storage options. Fortunately, storing your filaments doesn’t have to be a complicated matter. You won’t need any sophisticated materials or equipment. You should be able to get all the stuff you will need in your local grocery store.

1. Store in zip-lock or vacuum bags

The first order of business is to keep your filaments away from moisture in the atmosphere. The simplest way to do this is to store the filaments in easily accessible vacuum bags. Since they play such a crucial role in filament storage, we recommend getting high-quality vacuum bags made of a thick plastic layer and with double-zipper mechanisms.

To make sure that you have as little air as possible inside the vacuum bag, we recommend getting one of those space-saver bags with a vacuum valve for sucking the air out, such as these from Ziploc and Hibag. A single vacuum bag should fit two to four regular-sized filament spools and are infinitely reusable.

2. Use a filament clip

The end-point of a filament tends to be pretty sharp and can easily pierce through the vacuum bag in which it is stored. A simple and elegant solution to this is to use a filament clip, a small piece of plastic that clips to the spool and holds the filament end-point in place. It also keeps the spool from unraveling. The best thing about using a filament clip is that you don’t need to buy it – you can just print it yourself.

3. Store with desiccant

The thing about vacuum bags is that there’s no way that you can suck out all the moisture from inside it, no matter how long and how often you vacuum it out. The most common practice is to throw in some desiccant inside the vacuum bag. A desiccant is a  highly hygroscopic substance that will draw the water to itself and away from the filament.

There are a lot of desiccant compounds available, but the most popular and the one you can most easily get your hands on is silica gel. You’ve probably encountered silica gel, even if you weren’t aware of it. Silica gel is found inside those packets that come with your brand-new shoes or bags when you buy them. They perform the same function, keeping the leather or polyester in these products from absorbing moisture and getting brittle.

The great thing about silica gel is that it so inexpensive. A bundle of 250 small packs will set you back less than $15. Throw in three to five of these packets inside every vacuum bag with your filaments, and you’re good to go. Just replace the silica gel packets after every couple of months to keep your filaments nice and dry.

4. Use humidity indicator cards

If you want to be certain that your filaments are kept moisture-free while in storage, you can throw in a humidity indicator card inside each vacuum bag. This card has color-changing indicators that you can use to easily check if the desiccant in each bag needs to be replaced. This is not a necessary step, but it’s worth considering since these cards are very cheap and can be used multiple items.

Final thoughts

It sounds mundane, but proper care and storage of your filaments play a big part in having a hassle-free 3D printing experience. The filaments may be sensitive to moisture in the air but preventing moisture uptake isn’t very hard at all. All the stuff you’ll need to keep your filaments dry are readily available and are all quite affordable.

Warning; 3D printers should never be left unattended. They can pose a firesafety hazard.