This is the quietest failure in the tea trade and it is almost always the lid.

Flat, not stale

Dry tea leaf does not go off in any dramatic way. What happens is that the volatile aromatic compounds — the ones doing all the work in a good blend — escape, and oxygen slowly dulls what remains.

The result is a tea that tastes fine and unremarkable. The customer does not think “this has gone stale”; they think “this blend is a bit boring”, and they buy something else next time. You never hear about it.

Where the air is getting in

Not through the steel. Through the gap between the lid and the shoulder, which on a decorative slip lid is a real clearance rather than a seal.

That clearance is deliberate — it is what makes a caddy pleasant to open one-handed at a kettle. It is a feature on a refillable caddy and a liability on primary packaging.

The two fixes

Either fit a gasketed lid, which compresses against the rim and genuinely seals; or keep the pretty slip-lid tin and put a sealed foil sachet inside it.

The second one is often the better answer for a gift line: the customer gets a beautiful refillable tin and the tea arrives sealed. We suggest it regularly and it is cheaper than the gasket.

What else shortens it

Light, especially on green and white teas — which is the argument against windows. Heat, so not the shelf above the oven. And other smells, because tea absorbs them readily.

None of these is exotic. They are just never on the packaging brief, which is why the packaging brief is where they should go.