Behind the Weave: What Makes Merino Worth It

Merino wool is not just warmer than cotton. It is warmer per gram, which is a completely different proposition when you are packing for a week in a carry-on.

The reason is fibre diameter. Merino fibres measure roughly half the thickness of a standard sheep's wool, and that fineness is what traps still air close to the skin. Still air is the actual insulator. The wool just arranges itself so the air stays put.

There is a second, less obvious benefit: wool manages moisture. It absorbs sweat vapour without feeling damp, then releases it once you are warm again. Cotton does the opposite — it holds water against your skin and stays cold.

The catch is care. Merino needs airing rather than washing, and it should never go in a tumble dryer. Handled correctly, a good merino sweater will outlast the fast-fashion layer you would have bought twice.