5 Signs Your PLA Filament Has Gone Bad

PLA doesn't last forever. Even sealed spools degrade over time, and open spools can go bad in just a few months. Here are 5 signs it's time to replace that roll.

1. It snaps when you bend it Fresh PLA has slight flexibility. If your filament snaps cleanly with minimal bending, it's likely degraded from moisture or age. Brittle filament also breaks inside the extruder, causing mid-print failures.

2. Popping and crackling during printing That sizzling sound means moisture is boiling inside the hotend. Wet filament produces bubbly layers and heavy stringing. Try drying at 50 °C for 4–6 hours—if popping continues, the spool may be too far gone.

3. Visible discoloration or spots Yellowing, fading, or white specks mean UV damage or contamination. The color won't print true, and impurities can clog your nozzle.

4. Inconsistent diameter If you measure with calipers and see swings beyond ±0.03 mm, quality control was poor—or the spool has absorbed moisture and swollen. Inconsistent diameter causes under-extrusion and clogs.

5. Strange odors while printing PLA should have a mild, slightly sweet smell. A sharp, acrid, or burnt odor suggests degraded plastic or additives breaking down. Time to retire the spool.

The good news: proper storage (sealed, dry, cool, dark) extends PLA life significantly. And starting with a quality spool helps too.

Every Arkforge PLA spool is vacuum-sealed with desiccant and made from virgin resin—so it arrives fresh and stays fresh longer.

Shop fresh-batch PLA filament.

Happy printing!

– Arkforge Team