How should I store thread?

In a closed box or drawer, away from light and damp. Thread degrades slowly and invisibly, and the first sign is usually a spool that keeps breaking for no apparent reason.

Light is the main enemy. Sunlight weakens fibres and fades dye. A thread rack on a wall by a window looks attractive and it is the worst place in the room. If you want the display, keep the threads you are currently using there and store the rest in the dark.

Then humidity. Cotton in particular absorbs moisture, and damp thread weakens and can mildew. A dry cupboard is fine; a damp garage or loft is not.

Then dust. An open rack collects it, and dust on the thread goes straight into the tension discs and the bobbin race. Closed storage keeps the machine cleaner as well.

Practical arrangements. A lidded plastic box, a chest of shallow drawers, or a hanging organiser inside a cupboard. Sorting by colour is pleasant; sorting by type and weight is more useful.

Keep the thread end tucked in, in the notch on the spool or under the base, so spools do not tangle with each other.

Test old thread before using it on anything that matters. Pull a length between your hands. Good thread resists; degraded thread snaps quietly with very little force. That test takes two seconds and saves an evening.

Polyester lasts almost indefinitely in decent conditions. Cotton, silk and rayon do not.