How to Fix PLA That Gets Brittle & Snaps – Why Does It Happen?

The problem of PLA filament snapping isn’t one that goes unnoticed and it does affect many people. But the question remains, why does PLA filament snap in the first place? I’ve wondered this myself, so I decided to look into the causes and offer up some solutions too.

Why does PLA filament get brittle and snap? PLA filament snaps because of three main reasons. Over time, it can absorb moisture which causes it to reduce flexibility, from the mechanical stress of being curled up on a spool, then straightened out with pressure and generally low quality PLA filament.

Many people think it’s solely down to moisture absorption when it comes to PLA, but there are actually a few other reasons so keep reading to get the important details on why your PLA filament gets brittle and snaps in some instances.

If you are interested in seeing some of the best tools and accessories for your 3D printers, you can find them easily by clicking here (Amazon).

The video below shows you how to remove broken filament from your 3D printer’s extruder.

Reasons Why PLA Filament Gets Brittle & Snaps

1. Moisture

What many 3D printer users have done to save their PLA filament from snapping is to store the spool of filament in a big plastic bag which has a valve to suck out the air out of it, essentially in a vacuum-packing fashion.

They also use reusable moisture absorbing packs of silica beads.

If moisture absorption was the problem that made PLA filament brittle and snap, you would find that your filament would break along the parts of PLA which have exposure to the moist air, but it’s only the parts which are straightened that break.

This means that even when your PLA filament is sitting idle, it can contribute to the filament breaking so easily. Even if your filament doesn’t snap, moisture can still cause brittle PLA prints to be made, reducing the overall effectiveness of your models.

We know that there’s more to it than just moisture because some users have had PLA filament snap in very dry environments and ran a few tests to see whether holding the filament straight causes it to snap through the guide tube.

2. Mechanical Stress From Curling

Your spool of PLA filament has constant mechanical stresses of being straight after having been curled around a reel for a long period of time. It’s similar to when you ball up your fist then open your fist, you’ll find your fingers curling up more than its normal natural position.

Over time, the additional stresses applied to the filament can cause it to get brittle and this can be the case with many other filaments that are held on a spool. The ones that lack flexibility can be affected by this in the same way.

Sections of the filament which are held straight have a higher chance of breaking which is what makes it more fragile.

3. Low Quality Filament Brands

Depending on your brand of PLA filament, some will have more flexibility than others depending on the manufacturing processes so this curling stress of your filament may not be seen in some brands, but may be a common occurrence with others.

Fresh PLA filament seems to have a greater amount of flexibility and allows for a little bit of bending with snapping, but over time they just start becoming more prone to snapping.

So when looking at the overall picture, it’s mainly down to quality control issues. Low quality filaments that don’t have the same manufacturing care are going to be more likely to suffer from this issue.

It’s important to keep in mind though, quality filament isn’t always the more expensive one. It’s more so due to the reliability and trustworthiness of the brand of PLA. The best way to find this is to sift through online reviews and find one with consistent praise and high reviews.

I personally find the ERYONE Filament on Amazon to be a great choice and well-loved by thousands of 3D printer users. HATCHBOX is a big name in the filament space, but I’ve seen recent reviews saying that they have been having quality issues recently.

The takeaway here is that all factors working together is the most likely cause of filament becoming brittle and snapping.

When just one of these factors are isolated, you’re less likely to suffer from this issue but when filament has absorbed moisture, been straightened out past its normal curvature and is of low quality, you’re going to experience this a lot more.

So if this is happening to you, follow the solutions outlined in this post and the problem should be solved.

How to Fix PLA Filament Getting Brittle & Snapping

1. Proper Storage

The best way to store your filament is in an airtight container or sealed bag with packs of desiccant (silica bags) to absorb moisture in the air around the container. This way you know that moisture won’t negatively affect your filament and will be ready for use in optimal conditions.

When you take the proper steps to store your filament, you can avoid a lot of the headaches that come with imperfect PLA filament.

A great pack of desiccant with great reviews on Amazon is the Dry & Dry 5 Gram Packs and it’s amazing for humidity control while being very easy to apply. Simply get one of the packs and throw it in the container and let it work its magic.

It can be annoying to have to re-spool your filament each time, but if it’s a hygroscopic filament (meaning it absorbs moisture easily from the air) it’s a necessary step to get the best printing results.

The reason this method works is that dry PLA is more flexible than moisture-filled PLA so it has less chance of breakage and being brittle.

It’s important to also keep your filament out of the way of direct sunlight and not exposed to temperature changes so in a location which is fairly cool, dry and covered preferably.

A vacuum bag is a great option for keeping the filament dry. A good vacuum bag includes a vacuum valve which makes sure to get all oxygen out of the bag using a vacuum cleaner.

These bags have the ability to protect the filament from water, odor, dust, and many other micro-particles.

The standard would be the SUOCO 6-Pack Vacuum Storage Bags from Amazon. You’re getting 6 16″ x 24″ bags along with the hand pump to easily compress your bag around the filament, similar to how it’s done before being shipped to you.

• They are durable & reusable
• Double-zip and triple-seal turbo valve seal – leak-proof technology for maximum air expulsion
• Can be connected to a standard vacuum cleaner for speed – the pump is great to use while travelling.

If you think you’ll be using vacuum bags consistently, the premium option are the VacBird Vacuum Storage Bags with Electric Pump.

The really cool thing here is the powerful electric air pump which makes it much easier and faster to draw air out of the vacuum bags. Operation just takes the push of one button to start/stop.

You can get yourself a perfect sized Storage Container from Amazon. Some people get one large container, while others get a few smaller ones to hold each spool of filament.

It’s a good idea to also use these desiccants to keep your filament dry.

I’d recommend getting the Dry & Dry Premium Silica Gel Packets from Amazon for a great price. They are widely popular and work really well for all your moisture-absorbing needs.

They can significantly reduce the moisture levels in the immediate environment and within the filament, but you’ll need a proper drying solution to take more moisture out of your materials.

This is where specialized filament drying/storage boxes come in.

2. Drying Out Your Filament

A good indicator of filament full of moisture is when it makes a cracking/popping or hissing sound when extruded or creates a rough surface on your prints.

The hygroscopic level of PLA, ABS and other filament can be the difference between how much moisture it will absorb from the air and even more so when in a highly humid environment.

Instead of living with the issue of filament breaking and being full of moisture, you can proactively dry out your filament with a simple method.

A specialized 3D filament box is a great option as it includes a heating and drying mechanism. You just have to set up temperature and heating time and it will dry up your filament properly.

These boxes are designed to resist high temperatures which ensure to dry your filament without damaging it.

Specialized 3D filament boxes of high quality can be found easily on Amazon.

These boxes have openable lids on the upper side, you can open it and place your 3D filament inside the storage box. These boxes could be expensive but the best thing about these boxes is that they not only protect the filament from moisture but can also cure it.

The premium option here that I would recommend has to be the SUNLU Upgraded Filament Dryer Box from Amazon. With the item beside you, say goodbye to wet 3D printing filament.

• Can dry filament and print at the same time
• Easy temperature settings adjustments according to filament type, humidity etc.
• Manually set your drying times (the usual is 3-6 hours)
• Compatible with most 3D printer filament out there
• Ultra quiet so it doesn’t disturb your environment
• Comes with a cool 2-inch LCD monitor to display temperature and time

You can also use your oven to bake the moisture out of the filament.

The ideal way to set the temperature is to set it below the glass transition temperature of the filament.

• For PLA, set the temperature at 104°F – 122°F (40°C – 50°C) and keep it in the oven for 4 to 6 hours.
• For ABS, set the temperature at 149°F – 167°F (65°C to 75°C) and keep it in the oven for 4 to 6 hours.

Some people have even used their printer bed set at a temperature of 180°F (85°C) then cover the filament with a box to retain the heat and it works just fine.

A less invasive, but still effective method of removing moisture from filament is to place the spool into an airtight container with packs of desiccant, rice or salt for a few days.

Many 3D printer users have used this method effectively and it does the job just fine.

After you’ve done this, you want to take advantage of the previous method above of proper filament storage.

3. Reducing Moisture in the Air

This method is great because we know the possible causes, and we take action before it negatively effects us in the first place. You can measure moisture in the air with a few devices to know if this is affecting your filament.

Once you’ve identified higher levels of moisture in the air you can take a simple step to reduce it:

• Get a dehumidifier machine

You have three levels that you can go for depending on the size of your room and how bad your moisture problem is. It doesn’t only translate to filament and printing but environmental health issues in general.

The first level is the Pro Breeze Dehumidifier which is cheap, effective for a small room and has great reviews on Amazon.

The second level is the Homelabs Energy Star Dehumidifier, a bestseller and highly efficient machine that removes moisture, prevents mold and allergens from affecting you and your property. It’s perfect for medium to large rooms and has a lovely modern design.

The third level is the Vremi 4,500 Sq. Ft. Dehumidifier, just an almost perfect device with an extremely high rating of 4.8/5 stars. This is for the professional 3D printer users who have a whole designated workshop space.

Many buyers of this product rave about it’s amazing product experience and it’s ability to remove continuous moisture with ease.

4. Buying Better Quality PLA Filament

As previously mentioned, the quality of filament you get can make a difference on how brittle your filament is and how likely it is to snap while printing.

The manufacturing process may be similar, but there are differences which set some brands apart from others so make sure you have a reputable brand that you regularly purchase from.

It’s always a good idea to try out a few different brands before being loyal to one so search on some highly rated Amazon brands and find your favorite.

After some trial and error with 3D printer filament brands, I’ve decided to choose the ERYONE PLA Filament brand because it’s competitively priced, and goes above and beyond for quality and customer service.

They are also rated highly on Amazon and have a history of great functional use.

It’s always a great feeling to open up your newly purchased PLA filament and see that it’s perfectly wrapped around the spool and gives off bright, vibrant colors.

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It gives you the ability to:

• Easily clean your 3D prints – 25-piece kit with 13 knife blades and 3 handles, long tweezers, needle nose pliers, and glue stick.
• Simply remove 3D prints – stop damaging your 3D prints by using one of the 3 specialized removal tools.
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