3D filament is expensive, and when we buy it, we tend to hope it will last us a long time. But, as with many things, this simply might not be the case.
3D printing filaments will go bad, especially if they are exposed to humidity. They can last anywhere from two months to two years depending on the ambient humidity. The best way to prevent filaments from going bad is to store them in an airtight sealed container with a desiccant or silica.
So, what do you do with all of those filaments you have lying around on your desk, and how do you protect them from water damage? Also, what is it that makes filaments vulnerable to humidity in the first place, and are the things you make with them vulnerable as well? We’ll cover all of this and more below!
The Life of a Filament
Many filaments have a structure that tends to absorb water when put in contact with it. Even if they absorb even a tiny bit at a time, that will add up to cause not only a slight swelling in the filament itself (which can damage its nozzle) but also some structural damage that can cause the builds that use the damaged filament to become brittle or lose strength. This property of being absorbent is known as being hygroscopic.
Several different kinds of filament are commonly used in the United States. Most of these can go bad when exposed to humidity. Here is a list (that is by no means comprehensive) of the different ways that a filament can go bad.
PLA
The only way to tell that PLA has been damaged is to start printing with it. If it damages the nozzle of your printer, creates a print with dark splotches on it, or makes a weak product, it might be expired. Water-damaged filaments can create bubbles, air pockets, and stringy buildup, none of which are ideal for 3D printing.
You can prevent your PLA from going bad by storing it in a cool, dry place or an airtight container with a desiccant or silica. This will prevent your filament from coming into contact with water entirely, making it less likely to sustain any kind of water damage.
A PLA filament can spend about two months in a hot humid spot or two years in a cool dark one before it goes bad.
PETG
PETG is similar to PLA, but it’s designed to be less sensitive to water. Because of this, it can survive for around a year before receiving any sort of damage from it. It will still end up getting destroyed by humidity, however, and so correct storage is very important if you plan to keep the filament for longer than that.
ABS
ABS is another fairly common kind of filament that can easily expire. Unlike PLA however, you might be able to discover that an ABS filament has gone bad because the color has faded. Exposure to moisture causes it to develop hairline fractures which can cause the products to be vulnerable to mold or bacteria, which will smell bad and potentially cause structural damage.
That being said, ABS can last for over a decade with the proper storage, especially if you dry it out before using it. Just watch out for discoloration and bad odors.
PVA
PVA is actually soluble in water, which means that humidity can destroy it beyond repair. PVA needs to be stored in a place where water can’t get to it, or else it will go bad quite quickly. Other filament types can usually be dried, but water is a death sentence for PVA.
Nylon, Polycarbonate, and Copolyester
All of these filaments are so hygroscopic that just two days in humid weather is enough for them to be completely ruined. These filaments all need to be treated with extreme care if they are to be used. Proper storage and care will prevent them from receiving moisture damage and will remove the need for them to be dried out before they can be used.
Most filaments are both hygroscopic and biodegradable, which means that they can in fact go bad when they have too much moisture. They can even break down over time if you leave them out for too long.
But if filaments can degrade, then what about the things we make with them?
Can 3D Printed Objects Go Bad?
Focusing on PLA, the answer is technically yes. Because PLA is made from biodegradable materials, it will break down over time and eventually decompose.
When stored at room temperature in a relatively dry place, it will take 15 years for the object to show any signs of decay. In fact, unless it’s left out in the sun, dunked underwater, or buried deep underground, it’s very unlikely to start breaking down before that time. It takes such a long time to decay that there’s really no need to worry about it.
The only exceptions would come if you choose to bury your print in the dirt and heat it up to about 140˚ Fahrenheit (60˚ Celsius) at which point it will start to degrade extremely quickly, showing signs of cracking and tearing after only six months.
Of course, there’s no way that anyone would do that on accident, so you won’t need to worry about PLA projects wearing down when they are used for regular circumstances.
While sunlight won’t make the object decay much faster, it will cause it to lose some of its color, especially if you’ve applied paint to it. However, this can easily be fixed with a quick touch-up to the paint job, and it won’t damage the structural integrity of the object.
That being said, the warmth from the sunlight can speed up the process of decay, so if you like playing with your 3D printed projects outside, you might want to keep that in mind.
Most 3D printing filaments are biodegradable, although the time that each one takes to break down might be quite different. Some will last longer than others.
But fifteen years is a long enough time that you’ll probably be able to replace the object long before it ever starts to be a problem. Given proper maintenance and care, you can probably keep them for even longer than that. As long as they’re in a relatively cool, dry place, they’ll be fine.
As a sidenote, PLA is actually recyclable under the right circumstances. Of course, you’ll need to clean any dirt and grime off of the print thoroughly and make sure that it’s made of 100% PLA. You can even recycle it at home to use for your next project if you really want to! You’ll need a specialized recycle extruder for your printer, but otherwise, you can do it yourself with only the printer and a shredder to break the print down into tiny parts.
Use the shredder to shred the print into 0.7 cm strips. Then, set up the recycled filament on your printer. You can now load the printer with the strips, which will come out as a filament thread. You may have a way to spool this thread up, but if not, you’ll just want to make sure that it coils itself as it hits the ground.
You can do this by pushing the new filament to one side as it hits the ground. This should help it coil pretty nicely if you do it right.
When you have it coiling the way you want it to, you can start fine-tuning to get the process. You’ll be recycling old PLA in no time, and that should save you quite a bit of money.
Can You Restore Bad Filaments?
Most filaments will end up going bad because they’ve taken on a large amount of water. This is actually a solvable problem much of the time. All you have to do is dry out the filament and it should be usable again. But how do you do that?
The best way to dry your filaments is with a filament dryer. Filament dryers are easy to use and reliable, as they have specific settings for each of the different filaments that you might need to dry. All you need to do is put the spool of filament into the dryer, pick the appropriate setting, and wait for it to dry!
The next best choice is a food dehydrator. Food dehydrators just happen to do the exact thing that we’re trying to do here, which is getting all of the water out of something that is wet. For PLA, run the dehydrator at 45˚ Celsius (112˚ Fahrenheit). For ABS, you’d want it to be much hotter, around 80˚ Celsius, or 176˚ Fahrenheit.
Finally, you could use an oven to dry out the old filaments, but ovens are rather unreliable at these sorts of things as they often aren’t exactly the temperature they say they’ll be. If the oven isn’t hot enough, then the filament won’t get dry. If it’s too hot, the filament can be permanently damaged. That makes ovens a fairly risky choice for filament restoration.
You can also sometimes dry out a filament by applying desiccators, but will only work if 1) the desiccator is already dryer than the filament and 2) you use a lot of desiccators.
Desiccators work by being so dry and so absorbant that water flows into them, but it turns out that if there’s enough water in an object, it will actually attract water better than the desiccator will!
Because of this, and the fact that even the strongest desiccator can only absorb up to 20% of their mass in water, desiccators are usually not especially feasible for use in drying out waterlogged filaments. They’re great preventative measures though, and it’s a good idea to store your filament with some desiccators nearby.
How to Prevent Damage
Of course, it’s usually better to prevent damage from occurring than it is to fix it after it’s already happened. If you don’t have the proper equipment, restoring wet filaments can be a tricky process that’s more trouble than it’s worth. So how do you prevent the need for drying entirely?
The answer is simple: store your filaments in a dry place. No matter what kind of filament you’re using, you can never be too careful about its storage location.
The first step is to find the coolest, dryest part of your home. This might be a basement if you live in a place where there are basements, or it could be a closet or a pantry that doesn’t have any windows and will never see the light of day.
Now that you’ve found your ideal location, you’ll want to move all your filaments there. But they aren’t safe quite yet! Your next step is to find either airtight bags or containers to sequester them away in. Some filaments come in airtight storage bags. If these are reusable, then great! You can keep your filaments in their original bag as long as you still have a silica packet to go with it.
You can also use storage bags as long as you have desiccants and humidity meters to go with them. These are fairly durable, and the desiccants can suck up any excess humidity. All you’ll need to watch out for is dust!
You can even use vacuum bags if you have them. These are great because they prevent any water from getting into the bag and damaging the filament. There can’t be any humidity if there isn’t any air.
Airtight storage boxes can also work well for keeping out the damp if used correctly. They can have quite a high storage capacity, meaning that you don’t have to store all of your filaments separately, which can be nice. You do need to make sure that the container has a sufficient amount of desiccant inside it, however. Even if new air won’t enter the box, there is still air inside the box.
Finally, you could buy a filament storage box. These are actually designed to store filaments, which makes them a perfect choice. Because they’re climate-controlled and perfectly dry inside, your filaments should last for their full shelf life when they’re kept inside.
However, these containers can be kind of pricey, and it might be cheaper to use more DIY methods. It’s up to you, as long as the filaments are stored safely.