The main issue with wet filament is that the water in the filament meets a 200+°C hotend when printing. It then quickly turns into steam, which you hear as a popping sound while printing.
This then causes little holes in the extruded filament where the water steamed up. Looks like miniature swiss cheese. This causes all sorts of trouble. The print becomes brittle and weak, almost foam-like, and can be broken by applying little force. Layer adhesion and first layer adhesion will be much worse. It often causes lots of stringing.
It’s usually not an issue for PLA (unless you have really high relative air humidity), but it’s a big issue for PETG, TPU and Nylon.
If you print any of these filaments, you really should get a heated filament dryer.
cmnybo@discuss.tchncs.de 2 days ago
The filament absorbs moisture and that causes print quality issues. It can cause things like bubbles, stringing, poor layer adhesion and a rough finish. PLA will get brittle when it absorbs too much moisture.
clay_pidgin@sh.itjust.works 2 days ago
Excellent to know. Thank you!