Merino Standards
Merino, measured in microns.
Merino is bought and sold on mean fiber diameter. A one-micron difference changes the price of a bale and the way a garment feels on bare skin.
REF-01
Merino Trade Bands
Common trade usage for merino fiber classes. Mills and wool brokers draw the lines slightly differently.
| Class | Mean diameter | Typical end use |
|---|---|---|
| Ultrafine | ≤ 17.5 µm | Luxury knit, premium base layers |
| Superfine | 17.6–18.5 µm | Next-to-skin apparel |
| Fine | 18.6–19.5 µm | Midlayers, suiting |
| Medium | 19.6–22.5 µm | Sweaters, socks |
| Strong | ≥ 22.6 µm | Blankets, outerwear |
REF-02
Why Wool Prickles: Comfort Factor
Prickle comes from the coarsest fibers in a yarn, not the average. Fibers thicker than roughly 30 µm are stiff enough to trigger nerve endings in the skin.
- Comfort factor — the percentage of fibers finer than 30 µm. Around 95% or higher is generally comfortable against skin.
- Coefficient of variation (CV) — how much diameters vary within a lot. Two lots with the same mean can feel different if one has a wider spread.
- Spin and knit — a tight, smooth fabric hides fiber ends better than a loose, hairy one.
REF-03
Bradford Count to Micron
The Bradford (or "quality") count is the number of 560-yard hanks one pound of combed top could spin. It still appears on suiting labels as Super 100s, 120s and so on.
| Bradford | ≈ Micron | Typical use |
|---|---|---|
| 90s | 17.0 | Luxury suiting |
| 80s | 17.7 | Next-to-skin knit |
| 70s | 19.1 | Fine knitwear |
| 64s | 21 | Suiting, sweaters |
| 60s | 23 | Sweaters, socks |
| 56s | 27 | Outerwear cloth |
REF-04
Base Layer Weights
For knit merino garments, fabric weight (grams per square meter) matters more than micron for warmth.
| GSM | Use |
|---|---|
| 120–150 | Warm weather, high output, layering under shirts |
| 170–200 | All-season base layer |
| 230–260 | Cold weather, lower output |
| 280–320 | Heavy midlayer |
Responsible Wool Standard (RWS) and ZQ certifications cover animal welfare (including non-mulesed sourcing) and land management.