Wool Testing Techniques

Wool and fiber are harvested from many animals but when most average people say the word wool they think of sheep’s wool and grades of wool gauged by wool testing techniques. Sheep of varying breeds are spread across the world but some of the finest wool comes from Merino sheep.

An entire wool grading system was based upon the amount of Merino blood was in the bloodline of the sheep being tested. This system assumed that the greater the amount of Merino blood in the sheep, the finer their wool would be. Generally speaking this would be so, but with genetics having a bit of randomization, there were variables in that system. Obviously the finest wool would have full Merino blood and the braid or coarsest would have less than 1/4 or no Merino blood in their bloodlines.

Testing a sample of cleaned wool by spinning yard from it and measuring the amount of yarn spun was another way of testing and grading wool. This spin count system graded the wool in the amount of yarn produced measured in hanks. A hank is a measurement that is 560 yards long or roughly 512 meters long. Measurements in this way ranged from very fine wool gauged at finer than 80 spins, and very coarse or braid wool that was coarser thank 36 spins.

Both of these methods worked fine for their time but contained many variables. The other breed that Merino sheep were bred to make a difference and the type of spinning equipment used to spin yarn were not consistent. A system of precisely measuring the diameter of the fibers has a more consistent testing and grading ratio.

Computerized machines measure the diameter of wool fiber in measurements known as microns. A micron is one millionth of a meter or roughly one twenty-five thousandth on an inch. Sometimes only one two inch (5cm) sample from the sheep is submitted for testing. It is a better determining factor if two samples from each animal are submitted for testing. A sample from the side of the sheep midway from back to belly and at the last ribs and a sample from the britch which is just above the flank and half way between the flank and the rear gives a variation. Once the samples are collected, they are packaged and sent to laboratories to be computer tested for average fiber diameter, standard deviation, and/or coefficient of variation is determined. Very fine fiber is under 17.70 microns and braid or very coarse fiber is over 40.20 microns. These results of the wool testing determine how much the wool is worth and how it will be used.

By: Alan Stables

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Alan Stables trades in greasy wool. For this, Alan has to have an understanding of sheep skins , the characteristic of a merino fleece, types of wool and wool testing to produce accurate details of the product on sale.