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So, now that you have got the results of a fleece test, what does it all mean? The following is a list of commonly used terms for fibre testing.


Micron: Unit of measurement for describing diameter of fibre. 1,000 microns = one millimetre.
Fibre diameter is the single most important fibre trait with regard to commercial processing.
It is also one of the most heritable fibre traits

Mic Dev: (Micron Deviation) The extent to which a sample deviates from the herd’s average.

SD: (Standard Deviation) A measurement to show how much a set of individual results from within a sample vary from the overall sample’s average. One standard deviation is how far from the average you need to go to capture about two thirds of the sample. For example, a staple has an average diameter of 20.0 microns with a SD of 5.0 microns. In this case, about two thirds of the fibres in the staple are between 15.0 and 25.0 microns. The lower the SD, the less variation in fibre diameter. SD is the preferred measurement for determining fibre diameter variation on individual animals. Alpacas with low SD generally have a softer handle, greater tensile strength, and less variation over the fleece area.

CVD: (Coefficient of Variation of Diameter) Is the standard deviation expressed as a % of the sample’s average. For example, if the average diameter is 20.0 microns with a SD of 5.0 microns, the CVD is 25.0%. (5/20 x 100)

CF: (Comfort Factor) Percent of fibres in a sample that are equal to or less than 30 microns. Fibres greater than 30 microns are generally responsible for the prickle sensation when worn next to the skin.

CE: (Coarse Edge) The % of fibres in a sample that are greater than the sample’s average by 10 microns.

<15%: The percent of fibres in a sample less than 15 microns.

CRV: (Fibre curvature) expressed in degrees/millimetre. Generally, higher curvature is associated with higher crimp frequency.

SF: Spin Fineness: Calculation using micron and CVD to represent the spinning quality.

Micron Profile: A graph showing the variation of fibre diameter along the staple.
Can be used for analysing the nutritional intake over the growing season.

Histogram: A bar graph depicting the distribution of fibre diameter for the sample. On the horizontal (y) axis of the graph is the micron of the fibre counts. On the vertical (x) axis are a series of numbers which represent the frequency of distribution of those fibres counted.

SL: Staple length expressed in millimetres. Staple is another term for fibre bundle

Max Mic. The broadest point along the staple, expressed in microns.

Min Mic. The finest point along the staple, expressed in microns.

FPFT: (Finest point from the tip) Millimetres from the tip to the finest point in the staple. An indicator for the ‘point of break’.

MFE: (Mean fibre ends) The average fibre diameter of the fibre ends [tip and base] expressed in microns.

Hauteur (predicted): The estimated length of fibres after scouring, carding and combing.
As a rule, the two most important properties of wool for processors are diameter & hauteur.