Merino wool: what the micron count actually means
Merino wool is not a single thing. The label '100% merino' tells you the fibre type but nothing about the fineness of the yarn, which is the factor that most determines how the garment feels against your skin. Two merino rollnecks at the same price point can feel completely different, and the micron count is usually why.
What a micron count measures
A micron is one thousandth of a millimetre. In wool, the micron count refers to the average diameter of the individual fibres. Finer fibres have a lower micron count and feel softer against skin; coarser fibres have a higher count and are more durable but can feel scratchy, particularly at the neck and wrists.
The threshold at which most people stop noticing scratchiness is around 18-19 microns. Below that, the fibre is fine enough that it bends rather than pricks when it contacts skin. Above 22 microns, some people find it uncomfortable for extended wear directly against the skin.
What this means in practice
A rollneck or a garment worn directly against the neck needs to be at the finer end of the range. 18-19 microns. To be comfortable for most people. A jumper worn over a shirt can be slightly coarser without causing discomfort. A heavy-knit outer layer can be coarser still, because it's not in direct contact with skin.
The merino rollneck we carry is an 18.5-micron yarn. We chose that specification because it sits at the fine end of what's comfortable for most people at the neck, without being so fine that the garment is fragile. Finer yarns. 15-16 microns. Are softer but pill faster and are less suited to daily wear.
Care considerations by weight
Finer merino (under 18 microns) should be hand-washed or machine-washed on a wool cycle at 30 degrees, laid flat to dry. It's more susceptible to felting if agitated when wet. Mid-range merino (18-20 microns) is more forgiving and can usually handle a gentle machine cycle. Coarser merino (above 20 microns) is the most durable and can often be tumble-dried on a low setting, though we'd always recommend checking the care label first.
Pilling is a function of friction and yarn construction, not just micron count. A loosely spun fine yarn will pill faster than a tightly spun coarser one. The best indicator is how the garment looks after six months of regular wear, which is why we keep samples of everything we carry and wear them ourselves.
If you're unsure which weight is right for you, bring a merino garment you already own to the shop and we can compare it directly to what we carry.