The value of an alpaca's fleece is determined by several factors including the fineness (hair diameter), density, staple length, and comfort factor (uniformity of fiber diameter, the handle and lack of guard hairs).

 

• Fineness:
  Fineness is calculated by measuring the diameter of the fibers. Diameter is measured in microns. Alpacas with micron counts below 18 are considered Royal, 18-20 is Superfine/Baby, 20-24.9 is Fine, 25-29.9 is Medium and over 30 is Strong. For comparison, human hair has a micron count of 40-100.  The main factors that influence an alpaca's fineness are color, genetics, nutrition and age.  An alpaca's first fleece is usually it's finest fleece. If an alpaca retains a low micron count as it ages, then its fiber genes are considered very good, and it is said to "be holding its fineness". Generally, an alpaca's micron count will increase with age. Usually, lighter color fleeces have an overall lower micron count than dark fleeces. Remember, micron counts are just one component to evaluating the overall value of a fleece.
   

• Density:
  This measurement refers to the number of fibers per square inch. This measurement can be determined scientifically by doing a skin biopsy. In a show, judges can press down on the fleece to see how much it resists pressure. The more density (or more fiber) the alpaca has, the better. A seven-pound heavy, consistent fleece may be more valuable than four pounds of a lower micron count fleece. Of course, the ideal is to have both!
   

• Staple Length:
  This defines the length of the fleece from the skin to the tip of the fiber. Alpacas usually produce 3-6" of fiber in a year. A longer staple length will usually increase the overall weight of the fleece. However, many mills have restrictions on fiber that is either too long or too short.
   

• Comfort Factor:
  This addresses the overall "feel" of the fleece. Excess medullation (course guard hairs) will diminish the overall soft.
  feel of a fleece. Also, uniformity is critical for a good "feel" or "handle". If the standard deviation of the fiber diameter is low (meaning most of the hairs have a similar micron count), the then the fleece will feel softer. For instance, if the micron counts of fibers in the fleece range from 16-35, the fleece is likely to feel far less soft than another fleece where most of the fibers are 19-22 microns and there are few guard hairs (30 plus microns). Most breeders send a 2"x 2" fiber sample from the middle side of the alpaca to a lab to have the fleece tested each year. This test generally does not cover density or staple length but focuses on the micron count and related statistics.
   

• Crimp
  This relates to the curvature of the fiber, or the number of waves per inch.  A high frequency crimp would have many shallow waves, whereas a low frequency crimp would have fewer, yet deeper waves. Most breeders prefer fleeces that have fiber arranged in neat bundles. (The photo top center of this page is of Christiano's deep, bundled crimpy fiber.) Although fiber mills do not typically take crimp into account when purchasing fiber, many experts believe that crimp correlates to fineness. According to Dr. Julio Sumar of Peru, “In the Peruvian conditions of alpaca breeding, crimpness is highly appreciated for the breeders. They used to say, “In 90% of the cases a crimped fiber is a visual indicator of fineness.” 
  
  
  Below is an example of Yokum-McColl fiber test. Remember, lower numbers are more desirable than high numbers.