25/06/2026
💦💦 MOISTURE LESSON #1 💦💦
Most common plastics like PLA, PETG, ABS, ASA and TPU absorb moisture from the air, between 0.3 to 0.5% of their weight in water. This moisture turns to steam and ruptures during extrusion, resulting in stringing and inconsistent extrusion.
This moisture can be removed through filament drying, where we heat the plastic enough to break the bond between the polymer and the water molecule.
Users with evaporative air-conditioning will experience more issues with moisture than those without. Climate also matters.
If PLA absorbs moisture as well, why don't we see as much impact compared to with PETG, TPU, ABS or ASA?
Very simple! Even when dry PETG and TPU will have a higher tendency to ooze due to their viscosity. Add moisture to the equation and this is worsened. For filaments like ABS and ASA, the hotter nozzle temperatures result in more erratic boiling of the moisture.
While we don't agree with how often the internet will diagnose issues as being caused my moisture, moisture is certainly something you want to rule out early (and keep spool dry during further testing) to keep your sanity. It only takes a few hours of exposure before filament will absorb moisture again (see comments).
If you see printing issues and are confident the filament is dry. Remember that incorrect temperatures / flow rates, printing speed (tool head, layer height or layer width) nozzle blockages & partial blockages, worn PTFE tube (or worn coupler), plastic residue in extruder gears, mishandling of filament (tangles) and filament drag will also impact extrusion.
