Yarn Microns And Softness


The holy man on the left is wearing a hair shirt?

We’re going to talk about yarn microns and softness, I promise. But first, we have to establish some standard of comparison. We’ve chosen the hair on your very own head as a place to start. Have you ever heard the term “hair shirt?” Apparently, monks in the middle ages would make shirts out of hair and wear them under their clothes as a subtle form of self torture. These were itchy and coarse enough to scrape the skin and cause minor bleeding. Yikes! If you run your hands through your own hair, you won’t find it so very unpleasant, but have you ever gotten a piece of your own hair caught on your eye? Or on your own tongue? Of course you have, and very unpleasant it is, too. And once you cut it, there is a sharp end that pokes into your skin in a nasty way.

What does this have to do with yarn and microns, you ask? Well, let me tell you. Since it isn’t pleasant or practical to make clothing or other fabric from our own hair, human beings began to consider using hair from other animals. Something softer and more comfortable. They looked around them and thought, “Horse hair? Nope; too coarse and not enough of it. Cow? Surely not. Goats? Well, their outer hairs are at least as bad as our own, but they do get a nice soft under coat in winter. Not much of it, but great if we can get it. Hmmm…maybe sheep?” And the rest is wooly history.

But that still doesn’t explain the whole micron to softness connection, right? Well, let me give you just a little bit more history and it will become clearer. When humans first started using sheep fleece for clothing, the sheep hair wasn’t as soft as we’ve come to know it. It was just a darn site better than horse or cow or human. These early sheep hair gathering humans began to notice that some of their sheep had hair that was softer to the touch than others. So, some humans started breeding soft haired sheep to other soft haired sheep and creating breeds with fine, soft wool.

As the breeds got established, even within breeds there could be variance. Just like human beings, sheep can have finer or coarser hair than their wooly cousins. The climate where they live, their diet, and how clean they keep can have a great effect on the softness of their hair. And if the softer wool was more prized, the breeders should be able to get a higher price for it, right? Of course. So, who gets to determine how much a particular fleece should be worth? Well, the buyers, of course.

But, rather than having each and every person who wanted to buy a fleece fondle each and every fleece available, experts with sensitive finger and a vast experience of wool would run a few lock through their fingers and give it a grade. Coarse, medium, fine, super fine, expialidocious, a fleece would get a grade, and price would be agreed between the seller and the buyer based on that grade.


For a long, long time, this was called  The Bradford Scale. To quote that fount of all internet wisdom, Wikipedia, “English wool handlers in the city of Bradford described wool by estimating (with experienced eyes) how many 560-yard hanks of single strand yarn could be made by a good spinner from a pound of “top.” (Top is cleaned combed wool with the fibers all parallel) The finer the average diameter of a single wool fiber, the more hanks could be spun. From a pound of “64s,” for example, sixty-four such hanks could be made (more than 20 miles!). From the finest wools, more than 80 hanks could be spun; from the strongest, perhaps 36 or fewer. Using ranges denoted by the stronger end (that is “44s” ran up to “46s”) wool lots were classified and prices derived.” So this is a somewhat complicated assessment, and completely subjective. It’s also only one of several systems. While the English used the Bradford Scale, the American system was based on breed or blood in an even more complex and subjective scale.

Now we have microscopes and lasers that are capable of measuring the exact diameter of a single hair from an angora rabbit. The unit of measure is the micron, which is one millionth of a meter or 1/25,000 of an inch. Really, really tiny, right? Well, yes. And this is where the softness part come in.


This chart shows a human hair as the largest fiber at 70 microns, and an angora rabbit hair as the smallest at 13 microns. You can get a better view of it in our newsletter.

We are able to distinguish the size and texture of small things, but not infinitely small. There is a limit to the diameter of fibers that we can feel. As we noted above, a human hair is coarse enough, and sharp enough if cut, to be clearly felt. But sheep have hair that is thinner in diameter than human hair. Some breeds of sheep even more than others. As the diameter, in microns, of the individual hairs gets smaller, we are less abel to distinguish one fiber from the bunch of fibers. The feel starts to blur into a single sensation rather than a thousand separate ones. The more we experience this blurring of sensation of individual fibers, the more we experience it as soft.





There are other factors that determine softness. The length of the fiber, how curly or crimpy it is, how sharp the cut ends are, how tightly it is spun, etc, will all have an impact on how much we can feel an individual hair out a bunch of hairs. But the size of the hairs is the biggest contributing factor.

This is why we like to feel a yarn before we decide whether we want to make something that’s going to go next to our skin. You’re probably aware that some parts of the human body have more, and more sensitive, nerve endings than others. Fingers rank really high in the number and sensitivity of nerve endings. But fingers can’t tell you how something is going to feel on the underside of your chin. This is why we encourage you to gently run a skein of yarn against your neck or under your chin if you’re planning on making a cowl out of it.

Also keep in mind, it’s not just a marketing ploy to get you to value baby alpaca more than merino. Baby hair on any animal is going to be finer than on an adult. And extra fine merino is not a subjective assessment. It’s smaller in microns and, therefore softer.

Written by mim


9 Comments on “Yarn Microns And Softness

  1. Very Nice…I always learn something reading these blogs. Thanks so much. Now how about the subtle shade differences in yarns? How do they make such even skeins of color from sheep who have so many different shades at once? The natural colors of greys and creams and naturals. I wonder this often and you do not have to answer…but Mim you probably do know as it seems you know all things wool.

    • I’m not sure I know EVERYTHING, Bridget, but I do know that. As the graders are grading for softness they are looking at other qualities as well, like crimp, staple length, and, yup, color. They sort colors with like colors so that when the fleeces are combed or carder together, they blend into a fairly uniform color consistency. But this years, or weeks, or even single day’s, fleeces may not be identical to the batch that came before it. Hence a “dye lot” kind of effect even when the wool is not dyed. You’ll get less variation if you have sequential fleeces from the same sheep, just like humans, a sheep’s hair won’t change color all that much from one year to the next unless they are exposed to a hugely different amount of sunlight. But the graders do a pretty good job of putting the creamy white with the creamy white and the slightly yellow with the slightly yellow, etc. At some mills, they might re-blend certain natural neutrals to make color variants…like light gray, or pale brown. It’s all in how you mix it. Does that explain it?

      • Certainly does explain it and that answered another wonder I have had for years. Life is amazing and there is so many tiny things to think and know about. Thanks dear one!

  2. Always so interesting and fun to read. Thank you again for another enjoyable and informative post!

  3. Great article! Thanks for posting. Your reply to Bridget in August 2016 is excellent. A great response to use when customers ask why two skeins of the same undyed yarn type (my main stock) are different. Kudos!

  4. Thank you so very much for the educational article.
    We live in Northern WI, US. I’m searching for Yak yarn, in a bulky weight, to knit boots for my husband. He’s in a wheelchair and is missing his toes on one foot.

    It’s “impossible” to find warm boots for him. I’ve written to companies and asked if they’d sell me 2 different sizes of boots and all responses were “No”.
    I thought I’d use Yak wool for the outside of the boot and incorporate soft roving wool for the inside.

    Do you have Yak wool in #5 weight that you might recommend for this project?
    I’d really appreciate any help you may give me.

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