Filament is cheap to store badly and expensive to store badly: a $25 spool ruined by humidity is $25 + failed prints + wasted time. Here's the storage system professionals use.
Know your enemy: humidity
Hygroscopic materials (PA, PC, PETG, TPU) absorb water from air. Targets: below 40% RH for PLA/PETG, below 20% RH for PA/PC. A $10 hygrometer tells you if you're safe.
The three-tier storage system
- Short-term (days): resealable bags with silica desiccant — keep the bag the spool shipped in
- Medium-term (weeks): airtight bins with desiccant + hygrometer inside
- Long-term (months): vacuum-sealed bags with fresh desiccant
Print-from-dry-box for critical jobs
For PA/PC long prints, feed from a dry box so the material stays dry during the job — drying first, then printing from open air, is wasted effort on humid days.
Desiccant maintenance
Silica gel absorbs until saturated. Recharge it: 2 h at 120 °C in an oven, then cool in a sealed container. Mark your desiccant with a recharge date.
Bonus: the 1-year test
Can't remember when you bought the spool? If it hisses or strings, dry it before printing — use our drying chart.