Fiber Reference
Wool and specialty fibers, side by side.
Every animal fiber has its own diameter, crimp, luster and memory. Those properties decide whether it belongs next to skin, in a sweater, or in a coat that has to last thirty winters.
REF-01
Sheep Breeds by Fiber Diameter
Fiber diameter is measured in microns (µm, thousandths of a millimeter). Lower is softer. Ranges below are typical; individual flocks vary.
| Breed | Typical µm | Character | Best for |
|---|---|---|---|
| Merino | 15–24 | Fine, dense crimp, very elastic | Base layers, fine knitwear |
| Cormo | 17–23 | Merino × Corriedale; uniform, springy | Next-to-skin knits |
| Rambouillet | 19–24 | French-bred merino line, lofty | Sweaters, hand-spinning |
| Corriedale | 24–31 | Medium, even crimp, easy to spin | Sweaters, felting |
| Bluefaced Leicester | 24–28 | Long, lustrous, drapey | Shawls, socks, sweaters |
| Shetland | 20–30 (wide) | Light, airy, many natural colors | Fair Isle, lace |
| Romney | 29–36 | Long staple, lustrous, durable | Outerwear, rugs, felting |
REF-02
Specialty Animal Fibers
Fibers from goats, camelids and rabbits behave differently from sheep's wool: less crimp, less spring, more drape or halo.
| Fiber | Source | Typical µm | Notes |
|---|---|---|---|
| Cashmere | Cashmere goat undercoat | ≤ 19 | US labeling requires an average of 19 µm or finer |
| Alpaca | Alpaca | 18–30+ | No lanolin, very warm, drapes and can grow |
| Mohair | Angora goat | 23–40 | High luster, halo, takes dye brilliantly |
| Angora | Angora rabbit | 11–15 | Extremely soft, heavy halo, usually blended |
| Yak down | Yak undercoat | 15–20 | Cashmere-like hand, natural browns |
REF-03
Blends & Treatments
- Wool / nylon (sock yarn) — typically 20–25% nylon for abrasion resistance. See Sock Yarn & Wool Blends.
- Superwash — scales are smoothed or coated so the fiber can't felt in a machine. More in Superwash Wool Explained.
- Wool / silk — adds luster and strength; slightly less elastic.
- Wool / alpaca — sheep's wool gives the bounce and memory alpaca lacks.
- Bouclé & novelty yarns — looped, metallic-wrapped or slubbed constructions; texture comes from how the plies are twisted, not the fiber itself.
REF-04
Choosing a Fiber
| If you need… | Look for |
|---|---|
| Next-to-skin softness | Merino or cashmere under ~19.5 µm |
| Durability and abrasion resistance | Romney, Corriedale, or wool/nylon blends |
| Warmth without weight | Alpaca, Shetland, or lofty woolen-spun yarn |
| Drape and sheen | Bluefaced Leicester, mohair, or silk blends |
| Machine washability | Superwash wool (check the label) |