Fibre Classification
The coarse, thick outer coat of fleece-bearing animals protects the undercoat from moisture and physical abrasion. This protective fibre is known as guard hair, and it differs from the fine undercoat in diameter, stiffness, and internal structure. In luxury animal fibres like cashmere or camel, these thick fibres must be separated to isolate the soft down.
The presence of these outer hairs in the spin lot degrades the value of the finished yarn.
Industrial Removal
Mechanical dehairing processes use specialized cards to separate the coarse strands from the soft undercoat based on weight and flexibility. Because guard hair has a hollow medulla and a thick diameter, it does not bend easily and can be thrown out by centrifugal forces. When the dehairing is incomplete, the remaining coarse fibres remain in the batch and compromise the yarn quality.
Fabric Defect
Coarse hairs that remain in the wool cause an unpleasant prickle on the skin when the garment is worn. This is because guard hair is much stiffer than the surrounding undercoat fibres, so it does not bend easily under pressure.
Quality Standard
Buyers of raw cashmere specify the maximum allowable percentage of coarse fibres before signing purchasing agreements. Lab tests are conducted by counting the fibres under a projection microscope or by using image analysis.
