all yarn starts out its life as a pile of fiber. Whether it’s woolen spun, worsted spun, or single ply, that yarn is fiber before it becomes yarn.
Depending on the fibers involved, that fiber will be processed in different ways. Plant fibers need to be softened and broken down, while animal fibers usually need to be cleaned and carded. Depending on the yarn construction process, the fibers might be dyed at this stage or might be dyed after they’re spun.
What Makes a Woolen Spun Yarn
Woolen spinning is a process that spins yarn directly from carded fiber, resulting in a lofty yarn that is light and fluffy. This construction process leaves more room for lots of air pockets between the fibers, which can create a cozy insulating layer against the body. For extra-warm projects, a woollen yarn is a great choice.
Worsted spun yarns have an additional stage of fiber preparation before the fiber is spun into yarn. During this process, the fiber is combed and straightened in a way that causes the fibers to line up parallel against each other very tightly. If woolen spun yarns have a lot of air in them, worsted spun yarns have almost no air inside them, thanks to this process that tightly compacts the fibers.
Both of the yarns we’ve covered so far usually have at least two plies of yarn that twist around each other. Single ply yarns, however, only have one ply of yarn. A single-ply yarn can be either woolen spun or worsted spun, but a worsted spun single-ply yarn will be more durable because the fibers have been packed together more tightly.
How to Spot Each Kind of Yarn
If you’re looking at an already finished knit garment, look for the stitch definition and fuzz factor (that’s a technical term). Fuzzier knits are more likely to involve woolen yarns, though bear in mind that fiber content can also play a role in fuzziness. A very smooth knit will almost assuredly be a worsted-spun yarn.
When you want a yarn with better stitch definition or a very durable construction, choose worsted-spun yarn. The multiple plies of yarn that have been combed smooth before spinning will give you yarn that is good for patterns with strong dimensional effects, like cables. The worsted style yarn is also good for garments or accessories where you want good drape, like a shawl or lace projects. This is also a good choice if you want a yarn with less air in it.
Woolen-spun yarns, on the other hand, are popular for knits where you want a little fuzziness but still need some durability. Colorwork or fair isle knitting is often worked in a woolen-spun yarn, and specifically, in nonsuperwash woolen-spun yarns. The woolen style gives the yarn some grippiness, which helps prevent the images from getting distorted as the yarn stretches with wear and washing. The fluffy wool in many woolen spun yarns is extra squishy, too, which many people find comforting.
Finally, a single-ply yarn is good for projects that don’t get a lot of friction while you’re wearing them. Think hats, scarves, and mitts for single-ply yarn. That’s because these yarns are more fragile, so will tend to wear out more easily with lots of rubbing. They can feel wonderfully soft, though, so are often an excellent choice for projects that come into contact with the more sensitive skin on our necks or faces.