Storing filament in a cold garage or shed

Separate room damp, condensation risk and the condition inside the spool box.

By the Filament Drying Lab team · Checked 2026-10-25

Keep filament protected from the room air, and pay attention to temperature changes when moving a cold spool into a warm workshop.

Dew point explains the cold-surface problem

Dew point is the temperature at which air reaches saturation when cooled without changing its moisture content. A surface colder than the surrounding air's dew point can collect condensation. Source: National Weather Service, checked 25 October 2026.

The humidity calculator estimates dew point from your temperature and RH readings. Compare it with a measured surface temperature if you have one. The tool cannot know the temperature at the centre of a spool.

Make moving spools deliberate

Before opening cold storage in a warmer room, consider whether the spool may still be cold enough to collect moisture. Keep the container closed while conditions stabilise, then check it before loading.

Avoid storing a spool directly where water leaks or visibly condenses. A dry box also needs an intact seal; it doesn't make an unsuitable location suitable for electrical drying equipment.

Keep a useful record

Note room temperature, room RH and box RH separately. If damp conditions recur, inspect the enclosure and desiccant as well as the room. Don't interpret a lower RH reading during heating as proof that a filament has completed its drying cycle.

For the spool itself, follow the maker's drying and storage instructions rather than trying to predict a safe exposure time from the weather.