Wool size is primarily measured by its fiber diameter, expressed in microns (µm), also known as micrometers.
Understanding Micron Measurement
A micron (µm) is one-millionth of a meter. Because wool fibers are very fine, this unit provides a precise way to quantify their diameter. The smaller the micron count, the finer and softer the wool. Fiber diameter is arguably the most important characteristic when determining the value and end-use of wool.
Significance of Micron Count
The micron count directly affects the following properties:
- Softness and Handle: Finer wool with a lower micron count feels softer and less prickly against the skin.
- Spinability: Finer wool is generally easier to spin into fine yarns.
- Drape: Finer wool drapes better in garments.
- Price: Finer wool generally commands a higher price.
Wool Grade Classifications Based on Micron Count
While there isn't a universally standardized system, wool is generally classified based on its micron count:
| Wool Grade | Micron Range (µm) | Characteristics | Typical Uses |
|---|---|---|---|
| Ultrafine Merino | 11.5 - 18.5 | Extremely soft, luxurious | High-end apparel, next-to-skin garments |
| Fine Merino | 18.6 - 19.5 | Very soft, high quality | Fine apparel, knitwear |
| Medium Merino | 19.6 - 20.5 | Soft, versatile | Apparel, knitwear, blankets |
| Strong Merino | 20.6 - 22.5 | Good balance of softness and durability | Apparel, upholstery, carpets |
| Fine Crossbred | 22.6 - 24.5 | Durable, good for a variety of applications | Apparel, blankets, outerwear |
| Medium Crossbred | 24.6 - 26.5 | Strong and resilient | Carpets, upholstery, industrial uses |
| Strong Crossbred | 26.6 - 30.5 | Coarse and durable | Carpets, rugs, industrial textiles |
| Coarse/Carpet Wools | 30.6+ | Very strong and durable, often with a hairy handle | Carpets, rugs, heavy-duty industrial uses |
Note: These ranges can vary slightly depending on the source and region.
Other Factors Affecting Wool Quality
While micron count is the primary determinant, other factors also influence wool quality:
- Yield: The percentage of clean wool after scouring (washing).
- Staple Length: The length of the wool fibers. Longer staples are generally preferred for spinning.
- Strength: The resistance of the fibers to breakage.
- Color: A consistent, white color is generally preferred.
- Crimp: The natural waviness of the wool fibers. Crimp contributes to elasticity and insulation.
In summary, wool size is most accurately measured by its fiber diameter in microns. This measurement is critical in determining the wool's softness, quality, and end-use applications. The lower the micron count, the finer and generally more valuable the wool.
