Filament Storage Guide: Keep Your Filament Dry

Moisture destroys print quality. UK humidity makes proper storage essential. Here's how to keep your filament dry and printing well.

Why Moisture Matters Most filaments absorb water from the air (hygroscopic). Absorbed moisture vaporises during printing, causing: - Popping and hissing sounds - Stringing and poor surface finish - Weak layer adhesion - Brittle prints - Inconsistent extrusion

Some materials are worse than others. Nylon absorbs moisture in hours. PETG takes days. PLA takes weeks but still absorbs eventually.

Material Sensitivity High sensitivity (store sealed always): Nylon, TPU, PETG, polycarbonate Medium sensitivity (seal after opening): PLA, ABS, ASA Lower sensitivity (but still benefits): PETG when new

If you're not sure, treat it as sensitive. Better over-protected than ruined.

Storage Solutions

Budget: Vacuum bags with silica gel (around £10-20) Resealable vacuum bags work well. Add 50-100g of silica gel per spool. Squeeze out air or use a hand vacuum pump. Effective and cheap.

Mid-range: Sealed containers with desiccant (around £30-50) Plastic storage containers with gasket seals hold multiple spools. Add colour-indicating silica gel that changes colour when saturated. Bake silica in oven at 120°C to recharge when needed.

Premium: Dry boxes with active drying (around £60-150) Dedicated filament dry boxes maintain low humidity and can feed filament directly to the printer. Worth it for serious users or if you print moisture-sensitive materials regularly.

**Signs Your Filament Is Wet** Listen: Popping, crackling, or hissing during printing indicates moisture vaporising Look: Excessive stringing, rough surfaces, or steam from nozzle Feel: Brittle filament that snaps instead of bending (especially PLA)

**Drying Wet Filament** Wet filament can be saved. Drying options:

Dedicated filament dryer (around £40-70): The SUNLU Filament Dryer S2 is purpose-built with 360° heating, temperature control, and feeds directly to the printer. You can print while drying. The best solution. *(Price when reviewed: ~£45 | Check price)*

Food dehydrator (around £30-50): Works well at low temperature settings. Ensure it reaches required temperatures.

Oven: Works but risky. Most ovens can't hold accurate low temperatures. Overheating damages filament. Not recommended unless you verify temperature with a thermometer.

Drying times: PLA: 45-50°C for 4-6 hours PETG: 65°C for 4-6 hours Nylon: 70-80°C for 12+ hours TPU: 50°C for 4-6 hours

UK Humidity Challenge UK indoor humidity typically ranges 40-70% depending on season and heating. Most filaments want storage below 20% relative humidity.

Winter (heating on): Indoor air is drier, less urgent Summer and autumn: Higher humidity, more attention needed Bathrooms and kitchens: Never store filament here

A cheap hygrometer (around £5-10) in your storage container tells you if your solution works. Target under 20% RH inside sealed storage.

Workflow Tips Keep only your current spool on the printer. Return spools to sealed storage when switching.

Don't leave spools out overnight. Even a few hours in humid conditions affects sensitive materials.

Date your filament. First-in-first-out prevents old spools degrading in storage.

Throw away badly degraded filament. If prints consistently fail despite drying, the damage may be permanent.

Prevention Beats Cure Drying filament works, but prevention is better. Seal new filament immediately after opening. Store opened spools properly. Check storage humidity periodically. Consistent habits mean consistently good prints.