Imagine you are planning for your 3D print; you slice it and adjust all the settings in your printer. Now, all you have to do is wait for a few hours before it is done printing, anticipating your perfect 3D print.
But when your 3D printer stops, the object that comes out is different than usual. What happened? Where did the error occur? It might be difficult to understand but one of the problems could be in your filament.
Many 3D printing beginners do not know that their filament has a shelf life. Meaning, the filament can go bad or ‘expire’ if exposed to the environment under a certain period. But do all filaments have a shelf life? What about PLA, specifically?
PLA, like any other 3D printing filament, does indeed have a shelf life ranging from two months to two years when left exposed to the environment. PLA shelf life is highly influenced by the exposure of air moisture. When properly stored in air-tight containers with silica packets, PLA filament can possibly survive several more years.
Also check out our article on Why Does a 3D Print Become Brittle? How To Fix It!
Shelf Life of PLA VS ABS
According to 3DPrintingAdvice, PLA’s “expiry date may range from one month to two years” when it is kept outside, exposed to the air. So, the shelf life of PLA depends on the exposure to its surrounding environment.
I also assume that lower-quality, cheaper PLA might have a shorter or unreliable shelf life. This is not set in stone. However, to be on the safer side, you can invest in higher quality PLA to avoid printing problems.
To better understand the span of PLA’s shelf life, we can contrast with other common 3D printing filaments such as ABS and PETG. Compared to PLA, ABS lasts significantly longer, surviving around 10 years.
PLA is also considered less durable and weaker when compared with ABS for 3D printing. Similarly, PETG is also estimated to last a long time before its quality starts to go down.
The difference in the shelf lives of these filaments primarily lies in the properties of the materials they are made out of. Most filaments are hygroscopic. This means that they have the tendency to absorb moisture from their surroundings.
PLA is no exception. It is a hygroscopic, biodegradable thermoplastic that is made out of renewable resources such as corn starch and sugar cane. This makes the filament relatively environmentally friendly. (Source)
How long PLA holds up its quality before going bad mostly depends on how it is stored. The shelf life of exposed PLA can be altered by keeping it in a proper storage system. You can potentially prolong the shelf life of PLA by making sure it is not exposed to the environment.
Proper Storage Techniques for PLA
Like most filaments, PLA is advised to be stored in air-tight containers where there is no access to moisture. Persistent exposure to sunlight is also not good for PLA. So, you have to keep your roll of PLA somewhere that is not under direct sunlight.
For more on this, we recommend that you check out our post How Long Can Filament Be Left Out? Tips On Storing & Using Leftovers!
To keep your PLA spool fresh and ready for 3D printing, many enthusiasts suggest keeping them in plastic cases with sealable lids. These can be made from any plastic food container. As an alternative, vacuum storage bags are another good option.
OR for a budget option, You could go for a Cheap filament Storage Bag (Amazon Link)
Also, check out Can You Leave Filament In A 3D-Printer? How To Deal With It!
Keeping silica packets in there along with your spool is also a great idea. Because the silica gel helps soak up any excess moisture that might be left in the container.
If you do not mind spending money on quality filament storage, then there are special filament storage and dry boxes you can buy. The PolyBox and SUNLU Storage Box are the top choices for this category.
The good thing about these specifically made filament boxes is that they do not only work for storing but also drying your filament. The PolyBox gives live temperature and humidity readings while SUNLU can heat up your roll of filament and get rid of any excess moisture.
The filament can be fed directly into your 3D printer, without having to remove it from the boxes through a little opening on the top. All storage boxes also help in preventing dust particles from accumulating on your filament.
Reasonable prevention is also to not over-buy spools of PLA. And only open the packaging of the filament when it is expected to be used in the same month or two. Because, if the filament is just sitting out and not being used, it is more likely to start deteriorating and go to waste.
Also check out this post on What Is A Filament Oiler In 3D Printing? Should You Lubricate Your 3D Printer
Why Does PLA Expire/Go Bad?
Why is there a certain shelf life for filament anyway? What are the reasons behind PLA, or any filament for that matter, ‘going bad’? There are a couple of important key responses to these questions.
One of them is moisture. As said before, PLA is a hygroscopic thermoplastic. It loves to absorb moisture from the air. But this is not a good thing. Moisture makes PLA turn brittle, weak, and easy to break.
That is the reason why it is so very important to store your filament properly and in dry boxes. It is also the reason why people living in tropical regions tend to experience their 3D printing filament expiring faster than those in other areas.
Regions with greater humidity are a problem for PLA as well. Humidity exposure for PLA can lead to lower quality 3D prints. It can cause the moisture-absorbed filament to increase in diameter and weight. So, make sure to keep your filament in a room where the humidity level is on the lower spectrum.
Your 3D printer’s extruder can also experience jams if you feed it PLA that has absorbed a lot of water. It also weakens the entire structure of the filament and, as a consequence, the structure of your 3D printed time as well. (Source)
To read more on brittle filaments and 3D printed items, check out our article: Why Does a 3D Print Become Brittle? How To Fix It!, on another note, you may also think about the life span of 3D printed homes, which is covered by us in How Long Do 3D Printed Homes Last? Materials Used, Durability & Lifespan.
How To Tell If PLA Has Gone Bad/Brittle?
Now that you know the what and why of the problem, it is time to know the how. How do you recognize when your filament, or PLA, has gone brittle?
There are a few recognizable ways to distinguish a good and useable PLA from one that has gone bad. Signs that point out your PLA might have started to break down:
- The appearance of holes in your 3D printed item: The moisture trapped inside your PLA transforms into steam when it comes into contact with the intense heat of the 3D printer. This can cause irregular flows of filament and make holes or gaps in your print.
- Weaker filament/3D prints: This is fairly straightforward. When you print, your finished model would bend and snap easily if you apply little to no pressure on it. The same goes for the filament, if your PLA snaps easily when you pinch an end of it off from the spool, it has gotten weak.
- Jammed 3D printer: This is a bit of a late sign but if your 3D printer’s hot end or extruder is jammed, it might be because of your bad PLA. The PLA probably has an inconsistent diameter along its length that can clog up the extruder.
- ‘Weird’ noises from your 3D printer: When you try to print with the bad suspected filament, you will hear “sizzling” or “popping” sounds during the process. This might be due to the excess moisture escaping from the intense heat experienced on the hot end of your 3D printer.
Also check out our writing on How Much Does It Cost To DIY 3D Print? Filament, electricity, post-processing…
How long does a 3D printed item last when it is made from PLA?
According to the Ecoreprap 3D printing blog, “an object made of PLA will at least 15 years when kept indoors.” That is, of course, if there is not any persistent exterior damage, heavy load, or harsh conditions you put your PLA print through.
Comparatively, ABS prints are expected to last longer since the material is more temperature and shatter-resistant than PLA.
Can I print with old PLA?
Yes, you can. But before you can begin to 3D print with your old PLA, there are some additional steps you need to take. You would have to cook your PLA at a temperature of around 40 to 45°C to remove any moisture and dry it completely.
This ensures precaution so your printer will not jam when you feed it old PLA. You also have to take extra care to use it up quickly and not expose it to further moisture. Because cooking the moisture out of it is not a permanent solution and might not work every time.
To sum up everything, PLA does have a shelf life. Particularly, one that lasts somewhere around a month to two years under an exposed environment. But you can alter this shelf life by storing it properly and keeping it away from moisture. Because moisture and humidity can ruin your PLA and cause poor quality and weaker prints.
Also, we highly recommend that you check out our post “How Much Weight Can A 3D Printed Object Hold? Can You Make It Stronger!“