You might think that the term 'woolen yarn' has to do with yarn being made from wool, but it actually refers to a spinning technique. The process creates a less than perfect yarn as compared to one that is spun with the worsted method. You will find that woolen yarn is fluffier, often has varying degrees of thickness, and creates warm, soft knitwear.
What is woolen yarn?
In the spinning world, woolen yarn refers to a particular way of preparing the fiber and a specific spinning technique that can be used on a variety of fibers.
In contrast to the worsted method of spinning, woolen fiber preparation isn't concerned with lining up all the fibers or making sure that the fibers are of the same length. When the fiber is spun in a woolen style, the twist is allowed in the drafting zone. This means that the twist is worked into the fiber before it is thinned out of the fiber supply.
Spinner's Lingo: The 'drafting zone' is the space between a spinner's hands where fibers are separated and evened out. In worsted yarn, the twist is worked after the drafting zone and in woolen yarn, it is within the drafting zone. It is also called the 'drafting triangle.'
Woolen spinning is fast and a little wild and untamed. Trying to control the yarn too much only results in trouble and a much slower process. Since the fibers aren't arranged before spinning, this yarn has air pockets that are not found in worsted yarns. That makes the woolen yarn much fluffier, softer, and warmer.
To further complicate matters, some yarns can be both woolen and worsted. This usually happens when a previously spun woolen yarn is respun using the worsted technique. These yarns may be called semi-woolen or semi-worsted, depending on the exact technique used by the spinner.
The Pros and Cons of Woolen Yarns
To the knitter, woolen yarns are nice to work with and can be used to create some of the warmest garments you can imagine.
However, this yarn does have a few drawbacks that are a result of the looser -- or more free-form -- spinning of the fibers.
Woolen yarns do not provide good stitch definition because it tends to produce a halo around the stitches.
Woolen yarns are not very strong, though plying can improve its strength. Again, plying requires a spinner and you can find plied woolen yarns. Simply keep the fabric's strength in mind when pairing yarns and projects. Weaker yarns may be great for a chunky scarf but not hold up to the wear of a sweater and certainly not socks.
Woolen yarns can felt or pill easily over time with normal wear. This is again due to the loose fiber construction and greater care should be taken when caring for garments made with woolen yarns.