PLA filament is one of the most popular materials in 3D printing, loved for its ease of use, environmentally friendly nature, and consistent results. However, every 3D printing enthusiast eventually encounters a frustrating issue: PLA filament that snaps unexpectedly or becomes so brittle it’s almost impossible to work with. Understanding why this happens, how to fix it, and what you can do to prevent it in the future will save you time, money, and countless failed prints.
Understanding Why PLA Filament Becomes Brittle or Snaps
The first step to solving any problem is understanding its cause. PLA filament is generally quite flexible and sturdy, but under certain conditions, it can lose these properties. Brittleness often shows up as filament breaking with very little force, cracking during unspooling, or shattering during the feeding process. If you notice your filament breaking frequently—especially if it’s occurring in multiple places—it’s time to investigate and address the root cause.
Immediate Steps to Take When Your PLA Filament Snaps
If your filament snaps in the middle of a print, pause your printer and carefully remove the broken segment from the extruder and Bowden tube (if you’re using one). Avoid forcing the filament, as this could damage your extruder or clog your hot end. Check for additional weak spots or breaks along the filament and set aside any sections that appear compromised. Taking care at this stage will make the repair process easier and help you avoid further complications.
Causes of PLA Filament Brittleness
The most common culprit behind brittle PLA is moisture absorption. PLA is hygroscopic, meaning it naturally draws in moisture from the air over time. Even a few days outside of its original packaging in a humid environment can cause PLA to become weak and snap easily. Another factor is the age of the filament—older filament, even if stored properly, will gradually degrade and lose flexibility. Storage conditions are critical; filaments exposed to sunlight, heat, or drastic temperature changes can become brittle. Finally, in rare cases, manufacturing defects can result in a spool of PLA that is more prone to snapping, even when new.
How to Revive and Repair Brittle PLA Filament
The good news is that brittle PLA filament can often be saved. The most effective solution is drying. Place your filament spool in a filament dryer or a standard food dehydrator at 40–50°C (104–122°F) for four to six hours. If you don’t have a specialized dryer, an oven can also work, but be sure to monitor the temperature closely to avoid melting the filament. After drying, most filaments regain a significant portion of their flexibility and can be used reliably again.
If your filament has snapped, you can also splice the ends together. Use a lighter or soldering iron to gently melt the two ends and press them together, rolling the joint until it’s smooth and uniform. Allow it to cool fully before feeding it back into your printer. For filaments that are particularly brittle or have snapped in multiple places, consider rewinding the spool carefully, removing all compromised segments as you go.
Best Storage Practices to Prevent PLA Filament Snapping
Prevention is key when it comes to maintaining your filament’s longevity. Always store your PLA filament in an airtight container with a generous amount of desiccant packs to absorb excess moisture. Vacuum-sealed bags are another great option for long-term storage. Keep your filament away from windows, radiators, or any sources of heat and direct sunlight. If you live in a particularly humid area, consider investing in a dedicated dry box or filament storage system to keep your supplies in optimal condition year-round.
When to Replace Your PLA Filament
Even with the best care, no filament lasts forever. If your PLA continues to snap even after drying and rewinding, or if you notice persistent issues with print quality—such as under-extrusion, rough surfaces, or inconsistent layers—it may be time to retire that spool. Old filament can cause clogs, poor adhesion, and a lot of wasted time, so replacing it with a fresh spool is sometimes the best option. Remember, safety comes first: never force brittle filament into your printer, as this can cause hardware damage and more serious repairs down the line.
Conclusion: Ensuring Long-Lasting PLA Filament Performance
Dealing with brittle or snapping PLA filament is a common challenge, but it’s one that’s easily manageable with the right knowledge and tools. By understanding the causes of filament degradation, acting quickly to repair or revive your spools, and practicing proper storage habits, you can keep your 3D printing projects on track. With these practical solutions, you’ll ensure that your PLA filament remains reliable, flexible, and ready for your next creative idea. Take care of your filament, and it will take care of your prints.