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Is My Filament Too Wet?

Filament Moisture Dribble Test Calculator

Extrapolating from Pantheon Design's nylon test procedure (YouTube).

How To Do The Ooze Test

1
Preheat Set your nozzle to the print temperature for the filament you're testing. If the filament has been sitting in the printer exposed for more than a day, remove the first meter above the extruder and reload from the spool so you're testing the protected filament.
2
Prime and Start Timer Extrude a short length of filament to build hotend pressure, about 5 clicks on a Bambu printer. The moment the extruder gears stop, pull the strand off the nozzle, discard it, and immediately start a 30-second timer.
3
Measure the Ooze When the timer hits 30 seconds, pull the ooze strand off the nozzle and measure it with a ruler. Compare the length against the thresholds below for your filament and nozzle size.
What you're measuring: Moisture trapped in the filament boils into steam inside the hotend. The steam expands and forces molten plastic out the nozzle. Drier filament means less steam and less ooze.

Test Parameters

Very Dry
< 20mm
Optimal condition
Some Moisture
35-50mm
Usable, minor defects possible
Too Wet
> 50mm
Dry before printing
Expansion Ratio
2,702:1
Temperature
320C / 608F
Specific Volume
2.702 m3/kg

Reference Tables

MaterialTempNozzleDryMarginalWet
TempExpansion RatioFilaments at this range

How This Extrapolation Works

Reference point: Pantheon nylon test at 320C, 0.6mm nozzle, 30s wait.
Dry: <20mm, Marginal: 35-50mm, Wet: >50mm

Combined formula:
threshold = ref_length x (expansion / 2702) x (d / 0.6)^2 x (t / 30) x (1 / viscosity)

Limitations: First-order approximation. Calibrate with known-dry filament on your printer.
Sources: NIST Chemistry WebBook, Pantheon material handling, and Bambu filament TDS pages used for CF/GF viscosity examples via melt index: PET-CF, PAHT-CF, PA6-GF, PPA-CF, PA6-CF, PLA-CF.

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