Bottom line: moisture absorbed by nylon or PETG turns into steam inside the nozzle, creating bubbles, crackling and unstable flow. Drying and dry storage solve the cause; temperature adjustments only mask it. Drying must be followed by immediate sealing.
How it happens
| Stage | Process |
|---|---|
| Absorption | Material takes up atmospheric moisture |
| Heating | Water vaporises in the melt |
| Expansion | Bubbles form in the extrusion |
| Rupture | Surface blisters, noise, defects |
Practical drying
- PA: 70–90 °C for 4–12 h, per TDS.
- PETG: 60–70 °C for 4–6 h.
- PC: 80–120 °C for 4–8 h.
- Seal immediately after drying.
- Print from a dry box for long jobs.
Costly mistakes
- Raising temperature to hide the issue.
- Leaving filament exposed after drying.
- Over-drying at excessive temperature.
- Not monitoring storage humidity.
- Judging only by appearance.
Buyer / engineer checklist
- Is the material dry?
- Is it kept dry while printing?
- Is storage humidity controlled?
- Are drying cycles logged?
- Was a test part compared?
Tell us the material and storage conditions and we can help define the drying cycle.Drying advice