Why PLA Filament Becomes Brittle and How to Prevent It

 

You may notice your 3d printer filament snapping or shattering unexpectedly. This happens because pla is sensitive to environmental problems. Exposure to moisture, sunlight, or temperature swings can turn pla into brittle pla filament. Many users face pla brittle issues, especially after storing filament for a while. Problems like poor storage or rough handling often make pla more brittle. If you want strong, reliable prints, you need to protect your pla from these problems.

Key Takeaways

• PLA filament becomes brittle mainly due to moisture, sunlight, and temperature changes that break down its structure.
• Store PLA in airtight containers with desiccants and keep it in a cool, dry, and dark place to prevent brittleness.
• Handle PLA gently by avoiding sharp bends and tension to reduce stress and prevent filament breaking.
• Dry old or moist PLA filament at low temperatures before use to restore flexibility and improve print quality.
• Replace PLA filament if it snaps easily after drying, as it may be too damaged to print well.

PLA Brittle Causes

PLA filament brittle issues are common in 3D printing. You may notice filament breaking, snapping, or shattering, especially after some time in storage. Understanding the causes of brittle PLA filament helps you prevent print failures and wasted material. The main causes include environmental factors, storage and handling problems, and mechanical or printing stress.

Environmental Factors

Environmental conditions play a major role in making PLA brittle. PLA absorbs moisture from the air because it is hygroscopic. When you leave filament exposed to humidity, water molecules enter the material. This process, called hydrolysis, breaks down the polymer chains inside PLA. As a result, the filament loses flexibility and becomes brittle. Over time, you will see reduced strength and durability in your prints.

Tip: Always keep PLA away from excessive moisture exposure to avoid moisture problems.

UV light also damages PLA. If you store filament in sunlight or near windows, UV rays break the molecular bonds in the plastic. This leads to more brittle PLA filament and increases the risk of filament breaking during printing. Even though PLA resists UV better than some plastics, long-term exposure still causes problems.

Temperature fluctuations can weaken PLA as well. If you store filament in a place where temperatures rise and fall, the material can expand and contract. This weakens the structure and leads to brittle PLA filament. PLA’s glass transition temperature is about 60°C. Above this, the material softens and loses shape, which causes more breaking and reduced strength.

Common Environmental Causes of Brittle PLA Filament:

• Humidity and moisture absorption
• UV light exposure
• Temperature swings and heat

Storage and Handling Problems

Storage and handling problems often lead to brittle PLA filament. If you keep filament in a poor storage location, such as a damp basement or a room with high humidity, you increase the risk of moisture problems. PLA needs airtight containers with desiccants to stay dry. Leaving filament out in the open or in a box without a lid allows moisture to enter, causing age and storage effects that make the filament brittle.

Rough handling also creates problems. When you try to straighten filament that has become stiff, you may cause filament breaking. Pulling or bending the filament too much puts stress on the material, especially if it already absorbed moisture. Low-quality materials can make this worse, as they break more easily under stress.

Note: Always handle PLA gently and store it in a cool, dry place to avoid storage and handling problems.

Best Storage Practices Table:

Printing and Mechanical Stress

Printing and mechanical stress can also cause brittle PLA filament. If you use incorrect print settings, such as printing at too low a temperature, the layers do not bond well. This makes your prints weak and brittle. Printing at too high a temperature can degrade the filament, leading to more breaking and reduced durability.

Mechanical stress happens when you pull filament straight from the spool. PLA is stored in a curved shape, and forcing it straight puts tension on the material. This stress can cause filament breaking, especially if the filament already has moisture problems or has aged in poor storage conditions.

You may also see problems if you use high print speeds or excessive cooling. Fast printing does not give layers enough time to fuse, and too much cooling can make the layers brittle. Both issues lead to filament breaking and poor print quality.

Key Printing and Mechanical Stress Factors:

• Incorrect print temperature (too high or too low)
• High print speed
• Excessive cooling fan speed
• Mechanical tension from straightening filament
• Using old or brittle PLA filament

Remember: Adjust your print settings and handle filament carefully to avoid the most common causes of brittle PLA filament.

Solutions to Prevent Brittle PLA Filament

PLA filament can become brittle if you do not store or handle it correctly. You can avoid most problems by following a few simple solutions to prevent brittle PLA filament. These methods help you maintain filament quality, reduce waste, and ensure strong prints.

Proper Storage Methods

You need to focus on storage to keep PLA filament in good condition. Moisture is the main cause of brittleness, so you must keep your filament dry and away from humidity. The best way to do this is by using airtight containers or vacuum-sealed bags. Add desiccant packs, such as silica gel, to absorb any stray moisture inside the container. This combination creates a humidity-controlled environment that protects your filament from problems caused by water absorption.

Here are some effective storage solutions:

• Store PLA filament in airtight containers with tight seals.
• Use vacuum-sealed bags for long-term storage.
• Place desiccant packs inside containers or bags to keep humidity low.
• Keep filament in a cool, dry, and dark place, ideally between 15°C and 25°C (59°F to 77°F).
• Retain the original packaging if possible, as it often includes moisture barriers.
• Use a dry box or a filament dryer for extra protection, especially if you live in a humid area.

Tip: Regularly check the humidity inside your storage containers with a hygrometer. Replace or recharge desiccants when needed to maintain optimal conditions for storing PLA.

Desiccants work well for keeping humidity low, but they do not remove moisture already inside the filament. Always dry your filament before storing this material if you suspect it has absorbed water.

Handling Best Practices

Proper filament care goes beyond storage. How you handle PLA filament also affects its durability. Rough handling can create microcracks or stress points, which lead to brittle filament and print failures. You should always handle filament gently, especially when loading or unloading it from your printer.

Follow these best practices for handling:

1. Avoid bending or pulling filament sharply.
2. Gently unwind filament from the spool to prevent tension.
3. Keep filament away from direct sunlight during use and storage. Sunlight can heat and degrade PLA, especially dark colors, causing more problems with brittleness.
4. Inspect filament regularly for signs of aging, such as cracks or discoloration. Cut off any brittle sections before printing.
5. Use high-quality filament brands, as low-quality materials break more easily.
6. Track the age of your filament and use older spools first to minimize degradation.
7. If you notice brittleness, dry the filament at low temperatures (around 50°C) before use.

Note: Direct sunlight and high humidity during handling can quickly damage PLA. Always work in a shaded, dry area to avoid these problems.

Environmental Controls

Maintaining the right environment is key to proper storage and handling of PLA filament. You should store filament in a place with stable temperature and low humidity. The ideal temperature range for PLA is between 20°C and 25°C (68°F to 77°F). Relative humidity should stay below 40%, with 20-25% being even better for long-term storage.

To create optimal conditions for storing PLA filament:

• Use sealed polypropylene boxes with gaskets for the best moisture protection.
• Place bone-dry desiccants inside storage containers.
• Monitor humidity with a hygrometer and replace desiccants when needed.
• Store different filament types separately to avoid cross-contamination of moisture.
• Avoid storing filament near windows, heaters, or in rooms with frequent temperature swings.
• Regularly inspect your storage setup for leaks or signs of moisture.

Reminder: Problems like steam or bubbles during printing often signal moisture in the filament. Controlling humidity and temperature helps prevent these issues and keeps your PLA strong.

By following these solutions to prevent brittle PLA filament, you can avoid most problems and enjoy reliable, high-quality prints. Proper storage and handling, along with environmental controls, form the foundation of good filament care.

Restore Brittle PLA Filament

PLA can become brittle after absorbing moisture or sitting in poor storage. You do not have to throw away every old spool. You can often restore brittle PLA filament with the right drying techniques and a few simple tests.

Drying Techniques

You can remove moisture from PLA using several methods. The most effective way is to use a filament dryer. Set the dryer to 45°C to 50°C and let it run for 4 to 6 hours. This temperature range stays below PLA’s glass transition point, so you avoid softening or deforming the material. If you do not have a filament dryer, you can use a conventional oven. Set the oven to the same temperature range and monitor it closely. Some users also use a food dehydrator. For aged PLA, mild heating below 40°C for up to 24 hours can help release internal stresses and improve flexibility.

Tip: Always check the temperature with an oven thermometer. Never exceed 60°C, or you risk damaging your PLA.

Testing Filament Usability

After drying, you should test if your PLA is ready for printing. Start by inspecting the filament for bumps, scratches, or discoloration. Use a caliper to check the diameter at several points. Consistent thickness means smoother feeding. Try bending a small piece. Good PLA bends before breaking, while brittle filament snaps right away. Print a small test model, like a cube or boat, to check layer adhesion and strength. Adjust your print settings if needed and observe the results.

• Look for neat winding on the spool.
• Store dried filament in a vacuum-sealed bag with desiccant to keep it dry.

When to Replace Filament

Sometimes, you cannot restore brittle PLA filament. If your filament keeps snapping after thorough drying and gentle handling, it is too far gone. PLA exposed to open air for several days often becomes too brittle to save. If you notice the filament breaking during loading or printing, even after drying, you should replace it. PLA’s natural brittleness limits how much you can revive it. When drying and stress relief do not help, new filament is the best solution.

If you cannot restore flexibility or print quality, do not waste time—replace the spool for better results.

You often face pla brittle issues because humidity, heat, and poor storage break down the material. The consequences of brittle pla filament include weak prints and wasted supplies. To prevent these problems, use airtight containers, desiccants, and dry boxes. Keep your pla in a cool, dry place and check it often for signs of damage. Regular maintenance and smart storage help you avoid brittle pla filament and keep your prints strong. Make it a habit to inspect and care for your filament so you get the best results every time.

FAQ

Why does PLA filament become brittle so quickly?

PLA filament brittle issues often happen because the material absorbs moisture from the air. Sunlight and temperature changes also weaken the filament. You need to store PLA properly to slow down this process and keep your prints strong.

Tip: Always check your storage area for humidity and sunlight.

How can you store PLA filament to prevent brittleness?

You should use airtight containers or vacuum-sealed bags with desiccant packs. Keep your filament in a cool, dry, and dark place. This method protects against moisture and sunlight, which are the main reasons for PLA filament brittle problems.

• Airtight container
• Vacuum-sealed bag
• Dry box

Can you revive old or brittle PLA filament?

Yes, you can often revive old filament by drying it in a filament dryer or oven at 45–50°C for several hours. This process removes absorbed moisture and restores flexibility. If the filament still snaps easily after drying, you should replace it.

How do you know if PLA filament is too brittle to use?

Try bending a small piece of filament. If it snaps with little pressure, the PLA filament brittle issue is severe. You can also print a small test object. If the print breaks or layers separate, the filament is likely unusable.

What are the signs of moisture in PLA filament during printing?

You may hear popping sounds or see bubbles in your print. The surface might look rough or stringy. These signs mean your filament has absorbed moisture. Drying the filament can help solve these problems and improve print quality.