After 6 or more months, PLA Filaments become brittle and break easy. This make the filament not suitable for use. In our observation we found it happens irrespective of your region/climate or manufacture. Only the time may wary based on atmospheric parameters of the place where the filaments are stored.
The main reason for brittleness of filament is due to moisture absorption. ABS, PLA, and other common filament materials are mildly hygroscopic, so they will readily absorb moisture from the air. This is especially true if you live in a humid environment.
Below are the some of the most common symptoms that your filament has absorbed some moisture.
2. PLA filament swell and cause your hot end to jam. In worst case jams require hot end replacement.
3. Trapped moisture inside the PLA filament, becomes stream inside hotend which then interfere with the flow of plastic
4. Printed objects are weak
5. Makes a rough/grainy surface on finished prints
6. Filament is making a popping/cracking/hissing sound
If your filament is making a popping/cracking/hissing sound, or makes a rough/grainy surface on finished prints, your filament has probably absorbed some moisture. ABS, PLA, and other common filament materials are mildly hygroscopic, so they will readily absorb moisture from the air. This is especially true if you live in a humid environment.
The most simple way to remove the moisture is to place the entire roll in an oven for 2-3 hours at 185°F (85°C).
Warning: Many ovens do not have a temperature setting this low. If the oven temperature is much higher than 200°F, the fibers can cling to each other and ruin the roll.
A safer, but less effective treatment is to place the roll in a airtight container or bag with desiccant packs, salt and/or rice for several days or more.