How to choose Wool (fabric and yarn)

This post lists some important factors to consider when you go to buy wool.

Wool is durable, insulating, temperature regulating, naturally water-resistant, moth resistant, odor-resistant, and even stain resistant. What more do you want in a fabric? But in spite of its many unique qualities, there are still some complaints about wool, like itchiness, coarseness, heaviness, etc. Wool manufacturers have long tried to get rid of these complaints and make wool the number one choice for all purposes.

The quality of wool depends on certain parameters like the breed of sheep, the length of the fiber, quality of fiber, yarn twist and the spinning quality. The best wool is considered to be very strong but very fine with good elasticity and good felting properties.

Wool quality parameters when buying wool fabrics/yarn

Origin of wool

You can buy wool fabrics made from lamb wool if you want your fabric to be super soft – the lamb wool fibers came from a younger animal up to seven months old. 

Some categories of wool like merino wool, cashemere wool are more soft than other wool. Cormo wool is a soft wool obtained from Cormo, an Australian breed of sheep. Other soft wool fabrics are from breeds like Rambouillet and Polwarth. Breeds like Southdown and the Shropshire give medium fine wool. Wool from breeds like Karakul, Lincoln, Leicester, and Cotswold are considered coarser. 

Fabrics can be made of new/virgin wool or recycled wool (recycled wool fibers recovered from new or used cloth). Fabric made from new wool will be brighter than fabric made from recycled wool. The recycled wool fabric not only looks dull, it is also less strong and durable and also there will be a lot of lint.

Length of the fiber

Wool made of long  fibers make for a softer wool than that made of short fibers. It will be less itchy on the skin. You can read about the staple length of wool fibers here.

Super Numbers

According to the English yarn count system the fineness of the wool yarn is represented as Super Numbers. You may have heard of super 70 wool, super 100 wool. Super 250 is considered a high super number indicating pretty good quality of wool. High super number indicates more fineness, softeness and, luxurious feel.

But then a high Super number wool will be thinner, more prone to wrinkles, less warm than a thicker wool and very expensive

You can more info on super numbers here. 

Micron thickness of wool fiber

The best way to measure and grade wool is to consider the micron thickness of an individual wool fiber. This is one of the systems of American Grading of wool. Fiber diameter is usually used to gauge the fineness of wool fibers. Coarse wool fiber can have a diameter of even 38 microns, whereas finest wool fiber can have a diameter of even 14 microns. (To compare, this is several times finer than a human hair).

The smaller the number of microns, finer the fiber. Wool fiber with a micron thickness of 15-24 is considered good enough for next-to-skin apparel manufacturing.

Superfine wool – This refers to wool with a range of micron thickness of 15 to 18 microns.

Fine Wool – This refers to wool with a micron thickness range of 18-22. Wool from merino sheep is usually in this range.

Half-blood Wool – This refers to wool with a range of micron thickness of 22-25

Medium wool – This refers to wool with a range of micron thickness of 24 to 30

Braid Wool – This is the coarsest wool with a micron thickness of more than 30

Woolen vs worsted

When considering wool fabrics, you will be given a choice between woolen fabrics and worsted fabrics. Woolen fabrics are made of Yarns made from shorter wool fibers of 1 to 3 inches – they are thick and fuzzy. Worsted fabrics are made of smooth yarns made from longer fibers – smooth, lustrous and strong. 

Woolen fabrics are warmer but not as durable as worsted fabrics. Twill and Gabardine are worsted wool fabrics. Worsted wool fabrics are flat, more drapey and are considered to be the best fabrics for suits. Tweed and Flannel are woolen fabrics. For warmth and texture, woolen fabrics are better than worsted fabrics.

Fashion choices

If you are looking for a smart-casual option in wool tweed fabric is the best choice. Tweed is an all-time favorite and never goes out of fashion. You will have to choose a fine high-quality version of tweed.

If you want wool which has a backing and requires it to be strong and stable go for bonded or laminated wool. This material will have a bonded backing. It is great for making blankets, bags etc. 

Wool has high water absorbency but this quality also creates a problem – shrinkage. When buying yardage of wool this has to be taken into consideration.

Wool fabrics are not normally considered suitable to be washed at home – one of the reason being the shrinkage and another the change in the appearance – felted matted look. If you are not ready for the dry clean bill, choose wool which has undergone shrinkage-control treatments.

Durability

Handloomed wool fabrics are supposed to last more than those made in power looms.

A quality factor of wool yarn is the twist. A yarn with just the right twist will create a fabric that will last longer and wear well.

Comfort

Some people have an allergic reaction to wool when it touches the skin. This may be caused by an actual allergic reaction to wool or the strong chemicals and dyes used in processing wool fibers to yarn/fabric. This can be mitigated by washing wool fabric as well as yarn. You can hand wash wool in a suitable detergent and let them air dry flat, before the first usage itself. 

There is wool suitable for outerwear and those which are suitable for next-skin clothes like scarves, socks, vests etc. Finer the wool, more comfortable it will be against your skin.

Wool labels

In the US it is necessary that the label of the garment says whether the wool used in the garment is virgin or recycled. You can read more about The Wool Products Labeling Act of 1939  here. 

The Wool mark symbol can be used only on products made of 100% wool. The Wool blend Mark symbol can be used on products that contain a minimum of 60 percent pure wool and a balance of either natural or synthetic fibers. They are sponsored by The Wool Bureau, Inc., a trade association. 

Different classes of Wool

Class One Wool: This sheep class is said to have originated from Spain and is hailed as the best quality wool. The fibers are substantial, fine, and possess elastic fibers that are relatively short, ranging from 1 to 5 inches (25 – 125 mm). As a result, they have the highest crimp and the maximum number of scales.

Class Two Wool: This class of sheep originates from England, Scotland, Ireland and Wales. The fibers are comparatively strong, delicate, and elastic and range from 2 to 8 inches (50 – 200mm) in length and have a large number of scales per inch, and have good crimp.

Class Three Wool: Sheared from a class of sheep that originally came from the UK, these fibres are coarse, have lesser scales, and possess minimal crimps compared to earlier varieties. They are 4 to 18 inches long. The good quality ones are used extensively for clothing, thanks to its smoothness and luster.

Class Four Wool: Derived from mongrel sheep (half-breeds), these fibers are about 1 to 16 inches (25 – 400 mm) long, are coarse and hair-like, and have relatively few scales and slight crimp. This wool tends to be less preferred over the rest due to its minimal elasticity and strength. It is characteristically used for making carpets, rugs, and inexpensive low-grade clothing.

Reference for wool grades : https://aces.nmsu.edu/pubs/_b/B409/welcome.html ; Wool manual

Related post: Tips for buying best fabric;  Different names for wool fabric; Characteristics of wool fabric ; How is wool fabric made .