Guard hair
Also searched as: outer coat, coarse hair, underdown
Coarser outer hair in an animal coat, distinct from a fine undercoat.
In detail
Guard hair refers to the coarser outer component of a coat where it is distinguished from a finer undercoat. The distinction is especially useful when discussing cashmere preparation. The mixed raw coat and the selected fine textile fraction should not be treated as the same material specification.
The science and numbers
In double-coated goats, primary follicles grow coarse guard hair and secondary follicles grow the fine down sold as cashmere. The two populations barely overlap: in one study of Changthangi goats guard hair averaged about 68 microns in diameter against about 13 microns for down, and guard hair in Bakerwal and Kargil goats exceeded 100 microns. Proteomic comparison of cashmere, guard hair and sheep wool detected 159, 204 and 70 proteins respectively and pointed to the keratin KRT85 and the keratin-associated proteins KRTAP15-1 and KRTAP3-1 as candidate markers of diameter differences. Within a herd, guard-hair length correlates positively with guard-hair diameter and with down length. Guard hairs are often medullated, and an air-filled core raises light reflection and gives a chalky appearance, one reason residual coarse fibers are measured rather than judged by eye.
A practical example
For a fine animal-fiber purchase, ask whether the sample represents the raw coat or the dehaired product. A supplier’s fiber-diameter data should be interpreted alongside that description. A single average may not communicate the entire distribution of fine and coarse fibers.
What to distinguish
Guard hair is not a synonym for all animal hair, and the term alone does not identify an animal species. Its relevance depends on the coat and the intended product.
Origins and history
The distinction matters commercially wherever the underfur, not the outer coat, is the product. Beyond cashmere, researchers applied wool and cashmere test methods to qiviut, the down of the muskox, sampling 299 wild animals harvested on Banks Island, Canada, in 1997. They reported a theoretical yield defined as the percentage by mass of fibers of 30 microns or less, the same threshold US law uses to limit coarse fibers in cashmere.
Related terms
Sources & further reading
- Cashmere and Camel Hair Manufacturers Institute: Fiber definitions
- Gene: Characterization and polymorphism of keratin associated protein 1.4 gene in goats (2012)
- Frontiers in Genetics: Identification of the key proteins associated with different hair types in sheep and goats (2022)
- Animals: Phenotypic correlation between guard hair and down hair in Chinese Alashan Left Banner White Cashmere goat (2023)
- Journal of Animal Science: Fiber characteristics of qiviut and guard hair from wild muskoxen (2001)
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.