Kemp is a

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Br ...

, weak fibre forming the residual traces of a secondary coat in some breeds of sheep, which may be mixed with normal fibres in a wool fleece. This hair is not desirable in a fleece, as it does not accept dye, minimising both the quality and the value of the wool.

References

Sheep wool Spinning {{Textile-stub