I see a lot of people wondering why their 3d prints have little zits and voids in them. One of the potential reasons is because their filament has collected moisture. Filament is porous and collects moisture over time. Most filament manufacturers do a pretty good job of ensuring that filament is dry when it gets to you, but not always. Usually, moisture is absorbed when filament sits around in the house for a while.

When water is heated to 200 °C, like when you are printing with PLA, it turns to steam and then escapes, leaving little pockets on the surface of the project.

To ensure that you don’t have to worry about this, make sure that your filament is dry. You can do this by vacuum packing your filament if you aren’t going to use it for a while, using a filament dryer or food dehydrator to dry out filament before use, and keeping desiccant near the filament to absorb the moisture from your filament.