The guide to wool – Part I

As you may know, I originally hail from Italy. I was raised in Torino, but my entire family is from a tiny village in the alpine province of Biella.

Biella doesn’t offer anything particularly appealing, excluding incessant rain and a penchant for being stingy (or, as we say, “careful with money”), but, due to a combination of opportunity and abundant presence of water sources, the wool industry of Italy was born in Biella. There is significant evidence that textile manufacturing started there in pre-roman times, and survived several changes, from industrialization to off-shoring. While researching this article, I discovered that to this day, 40% of the global manufacturing of premium-grade wool still happens in these rainy and humid valleys. Incredible!

Needles to say, I was myself raised with wool. Lots of it. Full body underwear was a constant of my childhood, along with a lot of scratching. Relatives working on the looms would trade leftovers or slightly damaged cloth for other services, and no matter the reason, my grandma would always have a piece of cloth to give you to make an outfit for whichever occasion you needed.

Once I started sewing, I realized that all the knowledge I’ve accumulated over the years was really not obvious! I often get asked how to treat this or that wool, what’s the best for each project…

I am by no means an expert, but to share what I know I’ve decided to write a blog post on the basics of wool, especially for suits.

So let’s start, shall we?

What is wool?

Wool is the textile fiber which can be obtained from a variety of animals. Sheep (of which there are different breeds, such as Merino), goats (mohair and cashmere), rabbits (angora), and several camelids (alpaca and vicuña) are the most common, but other animals such as musk ox also give a woolly coat.

Now, you may have noticed that RTW in wool may state “virgin wool” or other marking. What are those, you ask?

Virgin wool is brand new wool, directly from the sheep to you (plus or minus some trivial steps like spinning, wearing, carding….). Generally speaking, this is the best wool, but its quality depends on the length of the fibers. Virgin wool from sheep too young to be sheared leads to short fibers which will wear poorly.

Reprocessed wool, on the other hand, is made by re-spinning and weaving wool scraps or articles which were never used. That said wool is a partially reusable resource.

Finally, re-used wool is made from used items. Because the process breaks down the fibers a lot, re-used wools have to blended with other fibers to give satisfactory results.

Worsted vs Woolens

Now that we have the basics covered, let’s move on to another major difference: that between worsted and woolens.

This difference arises from two different treatments the raw wool undergoes, namely carding and combing.

Carding takes the fluffy wool apart, cleans it, and reassembles it in a “sliver” (a loose strand of wool). Both long and short fibers are preserved by this process. Importantly, all wool undergoes carding before moving to subsequent downstream treatments. Fun fact: the name “carding” comes from the cardoon, as the dry flower of this plant was traditionally used for carding and in many cases it still is, as you can see from the picture below.

Carding at Zegna in 2018. Yes, those are actual cardoons!

After carding, a wool may undergo combing. Combing does exactly what the name suggests: it combs the fibers so they lay in the same direction and eliminates fibers which are too short.

To simplify, let’s say that carded wool, if spun, gives rise to a fabric called Woolen, whereas combed wool gives Worsted fabric.

Woolens are soft and hardwearing (generally speaking at least), they don’t wrinkle but also don’t hold a press. Because woolen yarns are made of coarser, mixed (long and short) fibers, only crisscrossed in the yarn, the weave is slightly open and the finish is soft. Most woolen yarns are one-ply (ply = twisted strands), and are loosely twisted.

Here are some examples of woolens.

Personally, I love the look of a nice tweed jacket, and have a Shetland suit in the works. Flannel is a very popular option too, thought if you are on the market for a flannel suit (or pants) I’d recommend a worsted flannel (like the one I used for my McCall’s 7726) which still retains the same coziness of flannel, but it’s much stronger and thinner (being a worsted). Alternatively, an old-school, thicker woolen flannel (13 oz or more) provides both durability and comfort…unless you are making fitted pants. In such a weight, a woolen flannel suit wears well and the trouser would be expected to only need an occasional repressing. Ultimately, it really depends on you and what style you are looking for. Because the fibers are not uniform in their length, they tend to wear out in high friction areas. They are fuzzy and nappy, a look which makes them more casual.

Now, worsted wools are a completely different game. If you remember from earlier, after carding these wools are combed parallel, and twisted into strands or”ply.” Two or more strands are then twisted together, making yarn that is even, strong, and firm. Both lengthwise and crosswise yarns have the same number of ply to make a fabric which is balanced for good wear. As with woolens, worsted fabrics come in different shapes and forms. A few examples are in the picture below.

Worsted suitings are generally close-woven, hard-finished, smooth, and supple. Crumple a piece in your hand; it will feel alive and springy, and will not hold wrinkles. Worsteds wear well but those without nap, such as serge and gabardine, become shiny. In general, worsted wools have excellent recovery, so it’s generally enough to hang your garment overnight to get rid of wrinkles.

After choosing between a woolen or worsted fabric, and in the case of the worsted also selecting a weave, the next thing to consider is the weight of the fabric. As with other fabric types the weight of wool cloth is given by the meter or the yard. Traditionally, this would be in ounces per yard (because the metric system has not reached tailors yet) at the typical suiting bolt width of 60″ or 150 cm. It is now also common to see the weight quoted in grams per meter (thank you!).

For worsted suiting, a good weight for a 3 season suit for most climates is in the range of 10-12 oz (240-270 g per meter, though this measurement is obtained in a slightly different way), depending on personal preference. There is now a trend towards lighter and lighter weights, even 8 oz or below, but this comes at the cost of hardiness, drape, and the ability of the garment to hold a press well. Such a light weight cloth will indeed be like wearing air, but it will also be a wrinkled mess after a few wears, and it won’t have the drape and body of a heavier cloth.

In fact, many argue that for a weight of 13 oz or more is better for a sharply tailored garment which will stand many years of wear. For winter a flannel or tweed at a weight of 13 oz or more is a good starting choice. For perspective, these same fabrics could in the past be found in the range of 15 to 16 oz.

An important point to consider, is that if being too warm is a problem, in the case of a summer suit for example, then impact of the fabric weave is more important than the weight. For example, a high-twist Fresco of 11 to 12 oz will be both breezier and better wearing than a 9 to 10 oz twill weave.

For worsted fabrics you may have also noticed the so called “super number” Sxxx which is sometimes noted on the selvedge of these fabrics. These numbers, ranging from S80 to S250 (!!!) indicate the maximum diameter of the fibers, measured in microns. A higher number means a lower diameter, which in theory leads to a finer cloth.

NameFiber diameter
SUPER 80’s19.75 µm
SUPER 90’s19.25 µm
SUPER 100’s18.75 µm
SUPER 110’s18.25 µm
SUPER 120’s17.75 µm
SUPER 130’s17.25 µm
SUPER 140’s16.75 µm
SUPER 150’s16.25 µm
SUPER 160’s15.75 µm
SUPER 170’s15.25 µm
SUPER 180’s14.75 µm
SUPER 190’s14.25 µm
SUPER 200’s13.75 µm
SUPER 210’s13.25 µm
SUPER 220’s12.75 µm
SUPER 230’s12.25 µm
SUPER 240’s11.75 µm
SUPER 250’s11.25 µm

Now, in my opinion, manufacturers have engaged in a “Super war” to get higher and higher S number as a marketing ploy, despite the fact that this does not offer a better cloth. This is mostly achieved by selective breeding of sheep, as different breeds naturally produce fleece with fibers of different diameter – Merino sheep naturally produce S80 – and sorting of the wool fibers. The issue is that a cloth above S150 will be more expensive, very light, will wear out more easily, require special treatment. At the same time, the main benefit, that being the difference in the fabric hand, is barely palpable (pun intended). For all intents and purposes, a worsted of around S100 will suit most needs, while a suiting of S80 or lower (i.e. no super number) can be a better choice for a garment which will get more wear (such as an everyday suit).

Now all the basics are covered! In part II I’ll talk about which wools to choose depending on your project, as well as how to care for your wool garments. If you have requests don’t hesitate to leave a comment below.

See ya!


7 thoughts on “The guide to wool – Part I”

  1. Very interesting and informative! I learned a lot. Thanks for taking the time and sharing!! les

  2. Wow! Thanks so much for writing this! So curious about whether you know some specialty techniques passed down from your family that we non-Italians don’t know! I’m staying tuned!!

    1. Thank you for reading! I’m not sure about special techniques, except maybe how to correctly sew buttons, haha! I’ll talk more about wool soon so maybe you’ll discover something you didn’t know 🙂 I surely have while researching this!

    1. Hi! That is an excellent question! I treat my woolens the same as my worsted garments. I don’t pre-wash my wool. Wool doesn’t need to be washed frequently, if not at all, and simple aeration is enough to eliminate bodily odors. When I’m making a suit, or pants, I don’t wash it. I line the front of the pant, and I hang after wear. I spot clean when necessary and always, ALWAYS brush my garment after use. I dry clean maybe once every couple of years. If wrinkles appear I generally press the area with dry iron+ironing cloth. Hope this helps!

  3. […] A common misconception, for example, is using high super number fabrics (more on the “super” here) as those fabrics tend to be lighter in weight. High super number textiles are, however, very […]

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