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May 26, 2022 5 min read

Designing a yarn is a strange process. It’s a combination of skill, experience, and luck - and it all starts for us with the fibre.

A farmers hands open up a Ryeland fleece on the sheep to display its staple.

Fibre first, not yarn first

Most yarn companies will first think about their ideal yarn - will it be drapey or lofty? Smooth or woolly? Once they have these qualities in mind, it’s a case of working backwards, finding the perfect fibre blend, spinning process and specifications to achieve this.

We’ve always done things a little backward - we start with the raw fibre, and let that dictate the way it goes. By working closely with our supplier farms up and down the country, we’ve always got a good idea throughout the year of how the fleeces are doing - not just at shearing time. That gives us a great idea of how it will respond to various processes, and lays the foundations of a number of design considerations.


The first time we get our hands on the wool is during grading (also known as /classing/), the process whereby we calculate what the farmer will be paid. In grading, we’ll separate the fibre into similar types - namely breed, colour and fineness. We’re also starting to get an overall feel for the fleece, and how it’ll likely perform when spun, but that level of control really comes into its own during sorting.


The vast majority of global wool that’s been graded will then go straight into production, where enough wool of a similar type is bundled together to create an average that’s suitable for a particular product. Annoyingly for us, we’re control freaks here at Garthenor Organic, so we put each fleece through a secondary process known as sorting.

In sorting, each individual fleece is opened up again, and divided into multiple different types. Across a single fleece, we might find half a dozen or so unique types, from the fine shoulder wool to the coarse britch wool - and that’s before we even break up the individual shades from coloured breeds like Jacob and Shetland! By splitting these types, we’re able to re-blend them during manufacture, but in a known mixture to more accurately predict how the yarn will feel, look and perform.

During this process we’ll be looking for seven primary factors:

  1. Strength, which is actually the term used for how thick or thin the individual fibres are, measured in microns from the finest (thinnest) to strongest (thickest). Our Polwarth fibre sits at around 18-19 microns, right up to Welsh Mountain and Herdwick fleeces that can easily be upwards of 40 microns!
  2. Soundness, which describes whether a fibre has tensile strength. An unhealthy sheep will usually present a weak point in the fleece, so an experienced sorter can “read” the farming year from the fleece, spotting any weak or damaged sections which will break and cause problems during spinning.
  3. Staple Length, the measurement of fibre from base to tip. Longer fibres (generally at least 75mm/3”) can be destined for the worsted spinning process, and the shorter fibres will make their way into woollen spinning.
  4. Lustre, or the degree of shine and brightness in a fibre. High lustre breeds like a Romney or Cotswold have a brilliant sheen once spun, especially through the worsted system, so we’ll prize particularly lustrous fleeces in some cases.
  5. Handle, which describes the feeling of the wool, from soft through to harsh. This is one of those annoying parameters that’s particularly tricky to define, and comes through years of experience in wool handling.
  6. Colour sorting also happens here, and not just sorting black, grey, brown and white. A careful eye is cast over each fleece, spotting slight colour variations that help build an undyed yarn blend - in some cases as many as a dozen individual colours may make up a heathery shade. There are also seemingly limitless shades of white, ranging from crisp snow white through to rich and creamy yellow, passing a whole gamut of greys, reds and browns. Some of these are almost imperceptible in the field, but once spun into a yarn can make all the difference. We’re also looking for any stains, discolouration or paint markings that’ll impact how we sort it.
    Grease content is the final key assessment, and one that can only be picked up through experience. Whilst it’s possible to measure grease content through laboratory testing (and we regularly do), the experience needed to create an even mix throughout a scouring blend is essential. Lower grease content will lead to a higher yield in scouring, therefore being more cost effective, but higher grease content protects the fibres better, and can prevent brittle, damaged fibre.

Throughout sorting, we’re also on the lookout for any number of faults which can affect how the wool will spin, and what type of yarn it will become:

  • Discolouration, or stain, often caused by suint (sweat), urine staining, wet fleece (known as fleece rot).
  • Double cutting, whereby a shearer has cut the wool a second time to tidy up, but introduces excess very short fibres of only a few millimetres.
  • Daggings, or dried, hardened dung that won’t scour out of the wool.
  • Excess vegetable matter such as straw, hay and twigs that won’t always come out during manufacturing, especially in the woollen process.
  • Contamination - every wool grader will have a wonderful list of items found in the wool sacks, from the usual string and notebooks to the more exotic - car keys, wedding rings and even mobile phones!
  • Excessive marking with sprays, used to identify sheep in the flock will sometimes cause a problem, and may not scour out.
  • Shearing after the rise will create a weak point in the fibre - the rise, or break is present in the fleece when a sheep is naturally ready to shear, and appears as a weaker point that’s easy to cut. If this grows out and the sheep is shorn too late, the weak point will be part way up the fibre and therefore unusable for spinning.
  • Cotts are the term used for felted wool. Soft cotts may be opened up in stronger wools without damaging the fibre, but heavy cotting won’t be usable without tearing the wool - not much good for spinning!

All the while, grading and sorting is done with a consideration of the breed of sheep. We’re aiming to produce yarns that reflect the sheep themselves, not purely to select the finest, longest and most lustrous fibres those breeds to have to offer. Sorting is the extra step to help us accurately predict and repeat the perfect blends, and is a whole load of extra work before production starts. Grading will usually take a few seconds per fleece, but sorting will take several minutes. It adds time and expense to the process, but most importantly it adds quality, and it adds magic.

All these factors combine to carefully sort the wool - sometimes into dozens of individual types - to be re-blended during scouring, carding or gilling.

It certainly takes an incredible depth of knowledge, skill and care to be able to accurately sort the wool, and it’s the most vital step in designing or repeating any of our yarns. Luckily for us, we have our very own wool whisperer, Sally. When she founded Garthenor Organic back in 1999, Sally was starting from a foundation of a love of all fibre crafts, especially spinning and knitting. Since then, her expertise of the wool we handle has only got more impressive

Interested in finding out more? Read our process of making a yarn below!

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