The pleasing softness felt when alpaca fiber is placed next to the skin can be attributed to a number of factors. The scale frequency and height refer to the structure of the individual fibers. Crimp is a measurement of the fiber's natural waviness. Sheep's wool typically has more crimp than alpaca fiber. Though it has been widely perceived that higher crimp per unit length is related to fineness and softness, fibers with decreased crimp have been shown to actually feel softer.
Higher crimps yield a thicker, rougher feel which is less pleasing to the touch.
Alpaca is considered a specialty fiber due, in part, to its luxuriously silky-smooth handle and also because it is rare and very much in demand. Sheep's wool, on the other hand, is found in abundance throughout most of the world. Alpaca fleeces tend to yield a higher percentage of clean fiber. Alpaca is lanolin-free and can be spun directly off of the animal. Sheep's wool requires cleaning proir to spinning.