And more strangely, does it suddenly go bad?
I printed this pair of glasses with a roll of ugly bright green PLA I use to print prototypes or silly things with - because, well, it’s ugly - at the last minute to go to a party where the idea is to not look too serious.
But it took me three tries: the nose bridge readily broke off the first print without even trying very hard, and one hinge split in the middle before I could even drive a pin through it. I was really careful with this third print and I managed to complete the assembly and leave to go to the venue.
But it’s really weird: this roll of PLA had been in the printer’s room for at least 2 years, I and others have printed a million things with it without any problems as recently as last week - including multiple iterations of these glasses - and today the prints feel “dry”, or less “waxy” that other PLA parts when I file them smooth, and they’re really brittle.
Also, it’s winter and here up north, it gets really dry in the winter - like 15% humidity - so I’m pretty sure the material is quite dry.
What gives? Any idea?
Just because it ran through the hotend doesn’t mean the moisture magically vanished. It’s not droplets of water in the plastic evaporating, it’s molecular water vapor. It’s still there, just probably less of it after being heated. Also, some plastics have volatiles that help with flexibility that disappear over time. Dunno if PLA or cheaper PLA has that issue, but it’s a possibility. I’ve found the same issues you have with PLA cracking when old after printing. Not sure what the cause is.