Symptom and Cause

The PTFE tube connecting the printhead to the dry box isn’t fully sealed. When the printer sits idle, filament in the tube absorbs moisture from the air, causing the first few millimeters of the next print to appear wet.

Open

First 1 mm of the print looks “crunchy”, but otherwise flawless, a sign of moisture ingress in the filament path.

If the next print runs immediately after and does not exhibit this defect, it confirms the issue lies in filament moisture rather than an insufficient first layer. Notably, the defect correlates with filament length rather than a specific height.

Approximately the first 1 meter of filament from the printhead to the spool box can become moisture-contaminated. For example, in a print with many parts, the initial layer will have a large material volume, so the defect may only affect the first couple of layers. However, in smaller prints (e.g., a 1-inch cylinder), the defect can persist for several layers, sometimes as high as 5–10 mm.

Solution

The most effective way to address this defect is to remove the first meter of filament before starting a print.

As of January 20, 2025, our machines feature an Auto Wet Filament Purge, a macro that automatically extrudes 1.2 meters of filament on the left side of the bed before starting the print file.

This macro activates only if the printer has been idle for more than 12 hours. If the purge macro has already run within the past 12 hours, it will not activate for subsequent prints.

Open

Auto Wet Filament Purge Setting

This functionality can also be toggled off in the extruder menu.