That means separating the unwanted coarse outer hair of the goats from the valuable ultrafine cashmere underfleece, which measures just 12 to 18 microns in width (one sheep wool fiber is more like 25 microns wide).

FORBES: Magazine Article

And understand that even a single wearing (or probably a lot of try-ons with your new sweater) means your natural-fiber clothes (wool, silk, cotton, cashmere, fur including blends) are no longer sterile when it comes to insects.

WSJ: Ask Teri: How to Keep Moths From Eating Sweaters