Before you choose
- A dry box maintains conditions; active drying removes moisture under defined conditions.
- Use the grade and spool temperature limits.
- Moisture symptoms also have other possible causes.
Check the symptom without jumping to a diagnosis
Popping, rough extrusion, stringing or a change in surface finish can justify checking moisture. Temperature, retraction, flow and mechanical issues can produce overlapping symptoms. Change one variable at a time and compare a recorded test before and after controlled drying.
Use the complete drying instruction
Confirm temperature, duration, air circulation and whether the spool itself is suitable. A dryer display measures its sensor location; the material may not reach that condition immediately. Avoid copying a high-temperature engineering-grade cycle to a low-temperature polymer or spool.
Keep dried material dry
Seal the spool for storage and control the feed path when the grade is moisture sensitive. Desiccant needs replacement or regeneration under its own instructions. A low air-humidity reading does not directly measure the moisture remaining inside the polymer.
| Step | Purpose | Record |
|---|---|---|
| Active drying | Reduce absorbed moisture | Grade, equipment, temperature and time |
| Sealed storage | Limit reabsorption | Bag/container condition and desiccant |
| Controlled feeding | Maintain conditions during a long print | Feed path and exposure duration |
| Comparison print | Check the effect | Same geometry and relevant profile settings |
Put storage into the purchasing brief
Ask for the supplied pack condition, closure and storage instructions. For recurring engineering production, define how an opened spool is identified and handled. If a batch dries differently from a retained sample, keep the lot and test records for investigation.
Questions buyers ask
Does a vacuum-sealed bag prove the filament is dry?
It shows a packaging method. Request the supplier’s product-specific condition and follow the required pre-print drying guidance.
Can a dry box replace a dryer?
Check the device’s function. Maintaining a low-humidity atmosphere and performing an active drying cycle are different tasks.
Sources
- Prusa — drying filament
Drying, storage and spool temperature limits; use the actual grade instructions.
- Polymaker — filament selection guide
Grade-specific equipment, drying and annealing requirements.