FilamentFix

FilamentFix

Diagnose. Dry. Store. Print.

STORAGE PLANNER

Keep dry filament dry—and know when storage is not enough.

Storage prevents new moisture exposure. It does not magically reverse a spool that is already wet. Use the interactive planner to choose a sensible storage level for your material and workflow.

Interactive storage recommendation

Build a storage plan in under a minute.

Choose the material, how you use it and whether the spool already shows moisture clues. The result separates active drying from storage so you do not use the wrong tool for the job.

Illustrative comparison showing a heated filament dryer actively removing moisture and a sealed dry box preserving dry filament

First question: is the spool already showing moisture symptoms?

Yes — popping, bubbles, rough extrusion or several clues together

Storage alone is not the fix. Diagnose first, then follow exact-product drying guidance when available. After drying, move the spool into controlled storage.

No — I just want to preserve a good spool

A sealed box or resealable bag with maintained desiccant is the right starting point. Add a hygrometer when you need to verify the internal environment rather than guessing.

Choose your material

PLA — lower storage priority, still protect it

Prusa’s USS Drybox documentation lists below 30% RH for PLA inside that drybox, with short-term tolerance up to 40%. BCN3D recommends dry, cool storage in a resealable bag and avoiding direct sunlight. If you print PLA regularly, sealed storage with desiccant is usually a sensible baseline.

PETG — give storage more attention

Prusa lists below 20% RH for PETG in the USS Drybox. BCN3D recommends keeping PET-G in an airtight container with desiccant when not in use. Bambu PETG HF specifically asks for below 20% RH while printing/keeping.

TPU / Nylon / PVA — high storage priority

These materials deserve stronger moisture control. Prusa identifies polyamide, PVA and TPU as materials that more often need drying. For TPU and PVA, the USS Drybox table lists below 20% RH, with TPU ideally below 15% in that system.

Engineering / composite material

Do not assume a generic target. Check the exact product’s TDS, support page or handling instructions. Some engineering polymers need much tighter control than hobby materials.

Pick the system that matches your use

Occasional printing

Best starting point: resealable bag or sealed container + regenerated desiccant. Keep exposure during handling short.

Frequent printing

Useful upgrade: sealed dry box + desiccant + hygrometer so you can print while limiting exposure and actually monitor RH.

Already wet / highly hygroscopic

Different job: use an appropriate dryer first, then move the spool into controlled storage. A dry box is not a substitute for active drying.

Reference RH values from Prusa’s USS Drybox

These values are published for humidity measured inside the Prusa USS Drybox. Treat them as system-specific reference points, not universal limits for every sensor, box and filament formulation.

MaterialMaximum recommended RH in USS Drybox
PLABelow 30% RH; short-term tolerance up to 40%
PETGBelow 20% RH
TPUBelow 20% RH; ideally below 15%
PVABelow 20% RH
PCBelow 20% RH
BVOHBelow 30% RH

Sources checked September 13, 2026: Prusa USS Drybox · BCN3D filament storage.

Storage guides