Fleece and Fiber

While body conformation, head shape, and dental structure primarily concern the quality of life of breeding animals, improved fleece translates into higher economic value. Textiles made from alpaca fleece offer a level of wearing comfort that is unique among natural fibers. The alpaca’s ancestor, the wild vicuña, produces the finest fleece currently processed in the entire animal kingdom. Thanks to its sustainable and environmentally friendly production, alpaca even surpasses cashmere. The luster of Suri fiber can even rival that of silk textiles.

We owe today’s high-quality fleece to the people who domesticated the wild vicuñas in South America long before the Inca era. They improved the animals so significantly over generations that even today’s breeding still lags behind their achievements. The fiber fineness of alpacas and llamas was just one aspect of Incan breeding expertise. Far more impressive was the uniform quality of the fleece they produced.

The fleece of all New World camelids consists of two layers. Colloquially, this is often referred to as “double coated.” These two layers are the outer and undercoat. The outer coat, also known as guard hair or primary fibers, protects the camelids from environmental influences such as weather and moisture, while the finer undercoat regulates body temperature. The highest proportion of guard hair among New World camelids is found in llamas, which were primarily bred as pack animals. Guard hair is practical for llamas as it increases durability and working capability. Their ancestor, the guanaco, also has more guard hair than the finely coated vicuña. However, alpacas are an exception. They are often described as “single-coated,” although this is only partially accurate. Over the course of domestication, the outer hair layer regressed significantly, acquiring properties similar to the undercoat—a deliberate breeding goal even before colonial times. Though not entirely gone, the guard hair has become so fine through controlled breeding that it is nearly indistinguishable. It remains potentially present but—depending on breeding success—is invisible within the undercoat. Thus, the extent of outer hair in alpacas today varies greatly. Top-tier fleeces are characterized by highly refined and unobtrusive guard hair.

Larger cuticle scales, spaced further apart, are crucial for fiber quality. When a fiber has fewer scales per unit length, the cuticle is more continuous. This results in a more unified surface area that reflects light more evenly, creating the characteristic alpaca luster—an especially important quality criterion in Suri fiber. The structure of the cuticle also affects how the fiber—and ultimately the resulting textile—feels. The flatter the scales, the softer the touch. If the scale edges protrude more, they create tiny hooks. Although these are changes measured in fractions of microns, the differences are noticeable. Fiber splitting analysis is a key determinant of quality—especially in Suri fleece. Suris are famous for their strong luster: thanks to their shallow cuticle scales, the fiber feels like it flows through your hands.

The cortex, the central shaft of the hair, is fully surrounded by the cuticle and also influences the fiber’s appearance. Two different cell types—paracortical and orthocortical cells—determine the fiber’s form. In Huacaya fleece, these cells are aligned on opposite sides of the fiber. This division causes the fiber to curl, creating what’s known as the crimp. It functions much like combining materials with different tensions: the tighter side pulls, while the relaxed side absorbs the force, resulting in uniform waves. The relaxed side always faces outward to maximize surface area. In fibers, the paracortex lies on the inside and the orthocortex on the outside. Differences in cell length cause differences in curliness.¹¹ However, crimp is not formed in a single fiber but rather through the collective structure of densely packed fibers that form a unified wave. In very fine and dense fleeces, this produces a beautifully defined fiber structure. In Suris, however, the two cell types are mixed throughout the cortex and not positioned on distinct sides. As a result, crimp is absent. The fiber instead falls in softly twisted locks along the animal’s body.

The final layer, the medulla—or hollow core inside the fiber—also plays a significant role. It influences fiber diameter and is primarily present in the more visible, coarser guard hairs. In finer fibers, the medulla may be partially present or completely absent. Conversely, it’s possible for coarser fibers to lack a hollow core. Without specialized equipment, it's difficult to determine if a fiber is medullated. Only the presence of coarse guard hair can be easily examined by eye.

¹¹Harland, D. P. et al. (2018): Intrinsic curvature in wool fibres is determined by the relative length of orthocortical and paracortical cells. In: The Journal of Experimental Biology, p. 221.

Excerpt from: PASSION FOR ALPACAS – CARE, BREEDING & SHOWS by editor and author Show Judge Robin Näsemann, 2020