Sweater Yarn 101: Wool

fiber types wool

Welcome to the Sweater Knitting 101 FIBER series! Choosing a fiber type for your sweater will greatly affect the fit, comfort and wearability of your sweater. In this series we will be talking about the characteristics of the different types of knitting fibers and why you might like to knit a sweater with each one. Today we’ll be taking a deeper look at one of the most popular knitting fibers of all time, sheep’s wool.

Wool Basics

Technically speaking wool is “the fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, angora from rabbits, and other types of wool from camelids”. However, today we will be focusing specifically on sheep’s wool.

Wool has several qualities that distinguish it from hair or fur: it is crimped, it is elastic, and it grows in staples (aka clusters).

The amount of crimp corresponds to the fineness of the wool fibers. A fine wool like Merino may have up to 100 crimps per inch, while the coarser wools like karakul may have as few as one or two. In contrast, hair has little if any scale and no crimp, and little ability to bind into yarn.

Wool fibers readily absorb moisture, but are not hollow. Wool can absorb almost one-third of its own weight in water. It is generally a creamy white color, although some breeds of sheep produce natural colors, such as black, brown, silver, and random mixes.

Let’s take a look at some of the many great reasons to try knitting your project with wool.

Benefits of Sheep’s Wool

Sheep’s wool is widely available and highly versatile which makes it the most popular type of wool. Because it is so easy to come by it can also be quite inexpensive. Wool fiber has a ton of useful qualities when it comes to knitting garments including the following:


The quality that distinguishes wool fibers from hair or fur is the presence of a hard, water-repellent outer layer that surrounds each hollow fiber which overlaps like shingles on a roof. The fiber’s core absorbs up to 30% of its weight in moisture vapor without becoming damp or clammy, while the hard outer layer protects against outside liquid moisture. Water is repelled, but humidity is absorbed, and that helps with thermal regulation.


Besides keeping outside moisture away from the skin, wool also wicks away perspiration. When you sweat, that sweat cools your skin-which is not what you want when it’s cold outside. Wool fibers absorb perspiration and wick it away from your body, thus keeping you warm and dry.


The crimp of the wool produces insulating air spaces that retain body heat. These warm air pockets next to the skin are kept dry while the hollow wool fibers absorb moisture vapors and the hard outer surface moves liquid moisture away from the body.


Wool has a very wide comfort range, essential for adapting to changing weather conditions. This unique property makes wool the perfect fiber to be used for outerwear and heavier garments, because it has the versatile ability to warm in colder conditions and cool in warmer conditions.


Wool can be blended with many different natural and synthetic fibers to create a multitude of fabric options.
Wool’s scaling and crimp make it easier to spin the fleece by helping the individual fibers attach to each other, so they stay together. Because of the crimp, wool fabric tends to be bulkier than other fibers. The cool thing is that insulation works both ways: Bedouins and Tuaregs use wool clothes to keep heat out and protect the body.


Wool ignites at a higher temperature than cotton and most synthetic fibers. It has a lower rate of flame spread, a lower rate of heat release, a lower heat of combustion, and does not melt or drip; it forms a char which is insulating and self-extinguishing.


Because the sheep’s hair grows in a spiral, the fibers have an excellent “memory” when twisted into yarn. That just means that wool maintains its shape when stretched and will bounce back into shape after wear or blocking. This handy feature also means that wool naturally resists wrinkling and static.

Now that you know some of the many reasons why wool is great to work with lets take a look at some of the most common types of wool used for producing yarn and knitting sweaters.

Merino Wool

Merino wool has superior shine, legendary softness, great breathability, and a lot of warmth with minimal weight. Merino sheep are most often raised in the mountainous regions of Australia and New Zealand. The wool is prized for its easily dye-able pure white color. It is fine, strong, naturally elastic, holds dye well, and its softness resembles the hand of cashmere. Merino wool does not have the itchy feel of some wools, is odor absorbent, and provides high levels of UV protection.

Today, there are more than ten varieties of merino sheep worldwide. Some well known merino breeds are Australian, Peppin, Saxony, Rambouillet, Vermount, and South African.

fiber types merino wool

Merino wool is very finely crimped and soft. Ultra fine wool is suitable for blending with other fibers such as silk and cashmere. New Zealand produces lightweight knits made from Merino wool and possum fur.

Merino need to be shorn at least once a year because their wool does not stop growing. If the coat is allowed to grow too long, it can cause heat stress, mobility issues, and blindness.

The term merino is widely used in the textile industries, but it cannot be taken to mean the yarn in question is actually 100% merino wool from a Merino strain bred specifically for its wool. The wool of any Merino sheep, whether reared in Spain or elsewhere, is “merino wool”. However, not all merino sheep produce wool suitable for yarn or clothing, and especially for clothing worn next to the skin. This depends on the particular strain of the breed. Merino sheep bred for meat do not produce a fleece with a fine enough staple for this purpose.

Shetland Wool

Raised in the Shetland Islands off the northern coast of Scotland, Shetland sheep produce very fine, lustrous wool from the down of their soft undercoat. The warm, lightweight Shetland wool is only available in limited quantities and natural colors and is mostly used in the production of high-end knitwear.

For knitting, shetland wool refers to a type of fine loosely twisted wool from Shetland sheep. It is one of the finest and softest of any UK breed.

This soft, yet strong and durable wool is a delight to spin and is ideal for knitting. Traditionally, the finest of the Shetland yarns, spun from selected neck wool, were knit into lace shawls so fine they could be drawn through a wedding ring! But don’t worry, it also works wonderfully for cozy sweaters.

One of the marvelous aspects of the Shetland is its variability within the breed. A small spinner’s flock can produce ultra-fine Shetland yarn for handknits as well as coarser, but equally gorgeous yarns suitable for sturdy socks and warm outer garments and remarkable tapestry yarns.

Shetland wool comes in one of the widest ranges of colors of any breed. Everything from the purest white to the deepest coal black. There are 11 main colors and 30 markings, many still bearing their Shetland dialect names.

fiber types shetland wool

Unfortunately, many of these colors and markings have become rare as white wool is dominant and for the last two hundred years has been preferred by commercial mills.

In some Shetlands, the wool will shed in late spring. For many generations the Islanders have “rooed” or pulled the wool off by hand during this period. This tendency toward molting, along with a double coat and a rich variety of natural colors is associated with more primitive sheep breeds.

Shetlands are one of the few breeds that can produce a true black fleece. This black is so dramatic it requires no overdying.

Icelandic Wool

Icelandic wool is generally known as “Lopi” and is knitting wool made from the fleece of Icelandic sheep. Icelandic sheep develop particularly dense wool hair to protect them against the harsh climate. It is very warm, sturdy, firm and water repellent and the underhair is very soft and fleecy. The fleece is made up of two layers, each with a different kind of wool. The water-resistant outer coat contains long, coarse fibres, while the insulating layer beneath consists of soft, short fibres. These are processed together to create lopi roving and yarn.

The machine-carded roving is produced in disc-shaped rolls. This is the original unspun lopi first used for knitting around 1900. More recently, lightly spun lopi yarn in different thicknesses has been available.

fiber types icelandic wool

Most wool produced in Iceland is processed by Ístex, the Icelandic Textile Company. They manufacture 3 types of spun lopi yarn and also unspun lopi. It comes in a variety of natural fleece shades, and in a range of dyed colours.

Characteristic Icelandic lopapeysa sweaters are generally made from the thicker lopi yarns. Because the yarn is so thick and the sweaters so warm they are really only suitable to be worn in very cold, northern climates.

Lambs Wool

Lambs wool is the highest quality of sheep’s wool on the market. Lambswool is taken from sheep at their first shearing (usually at around seven months old). It is supremely soft, smooth, resilient, elastic, and has superior spinning properties. Because of its soft silkiness and warmth, lambs wool fibers are used in the production of garments worn close to the skin. Lambswool is the most hypoallergenic of all wools and is resistant to dust mites, making it an ideal choice for bedding and linens if made into a fabric rather than a knitted project.

fiber types lambs wool

Keep Learning!

Join us next time as we talk about the other types animals that produce wool. Each individual animal brings out different attributes in the fiber that you may want to use with your next sweater project!

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