Wool and merino

Fine merino can be worn for days without smelling, and a coarse wool jumper will itch whatever the label promises. The difference is the micron number.

Reviewed: 2026-10-13

Wool fibre is measured in microns. Most people find wool below roughly 20 microns soft against bare skin; coarser wool is fine for outer layers and knitwear worn over a shirt. If a brand names the micron count, you can judge itch before you buy.

Wool absorbs moisture vapour into the fibre itself, which is why it feels less clammy than synthetics and why odour builds more slowly. Airing a merino top overnight often does the job of a wash.

Machine-washable wool has usually been treated so the scales on the fibre don't lock together and felt. That convenience is real, but untreated wool washed by hand lasts just as well if you never put it in a hot cycle.