We say "microns", what we mean is AFD or average fiber diameter, which just happens to be measured in microns since the fibers are so small. Two contributors to the feel of wool as defined by AFD are:
- The smaller the fiber diameter, the softer the wool is.
- If there are high diameter fibers mixed in with low diameter fibers in the same fleece, the wool product you produce from it will feel scratchy.
|Many years of micron data...|
We do this just before shearing so we get a full year growth to be tested. We do take samples of lambs in early fall before we put together our sales list just to get a data point to determine if a lamb has fallen out of our breeding program - based on micron numbers as well as other equally important criteria like handle, staple length, conformation, color, pattern, bloodlines etc. It is very unusual for us to sell lambs, as they change so much over the year - you might sell something that can really make a nice contribution to the flock, and we can't afford to make too many mistakes with our small flock size.
Anyways, each sample has to come from a specific location on the sheep's body - 5th rib back, vertically centered on the body. This is so you can compare sheep to sheep, flock to flock. Everyone who does this is on the honor system to make sure they take from the same location. If you take from the neck wool that is cheating as neck wool is the softest on the body. Sometimes we take samples from the britch, neck and 5th rib to see how consistent a fleece is on one sheep, but we don't claim those when we are publishing our results, unless we define it carefully.
|A fiber sample bagged, labelled and ready to ship out|
Texas A&M use their equipment to measure a sample of fibers from each of our samples. They measure the diameter of the staple, taking measurements along the entire length of the staple, and they do multiple fibers from each sheep. They also measure the staple length. Then they calculate the statistics of the sample, and provide you with the data and a histogram to go with it.
|AFD Summary Report from 2017 - this is the first page of the report, each row is data from one sample of wool. The far left column is the ear tag ID for each sheep|
This link takes you to a post where Rich nicely defines the terms used to measure fiber diameter. Its actually an outdated sales post from 2015, but if you scroll to the bottom you will find the definitions:
And these are really good posts Rich wrote about Shetland wool, I think they are very interesting, you might like them:
We use micron data as one of many data points to determine who gets sold and who becomes breeding stock as well as who to breed with who (whom?). I also publish the micron data for the wool I sell - it goes on every label of everything I sell.
|Label for some batting I have for sale, row five provides the micron data|
We don't typically purchase breeding stock without micron data, if the breeder doesn't have it, we obtain a sample from the breeder and send it in ourselves.
Hope this helps! Let me know if you have other questions.