Filament Storage Calculator — Desiccant & Container Sizing

Many filaments (especially Nylon, PETG and TPU) are hygroscopic — they absorb moisture from the air. Wet filament causes popping, stringing, poor surface quality and weak layer adhesion.

The general rule is 1-2g of silica gel per litre of sealed container volume (industry desiccant guides cite roughly 28-56g per cubic foot, which is 1-2g/L). Our calculator uses 2g per litre — the upper end, sensible for the humid UK climate. In practice a typical multi-spool dry box of 15-25 litres needs around 30-50g total, so for a single 1kg spool in a small airtight box you only need a 20-50g pack.

Yes. Colour-indicating silica gel changes colour when saturated (orange-to-green or orange-to-pale-yellow types are common). Regenerate it by spreading it on a tray and heating in a vented oven at 120-150C for 2-3 hours until the original colour returns, then store it airtight while it cools. It can be reused many times.

Large airtight plastic storage boxes with clip-on lids work well. IKEA SAMLA or Really Useful Boxes are popular choices. Add a hygrometer to monitor humidity.