Series on Wool: What is Merino Wool?

Series on Wool: What is Merino Wool?

Charlie Bradley Ross Tuesday, 20 January 2015

Don't we all love the softness and warmth provided by high quality woollen clothing? Wool is one of the oldest fibres used by man for its comfort and naturally insulating properties. Like most natural fibres, different grades and varieties of wool are available on the market. Of the various types available, Merino wool derived from the Merino sheep is one of the finest. This wool is characterised by it's premium quality and exceptional softness, and also possesses several other superior properties. Here's a closer look at what sets Merino wool apart from other types of wool.

Merino wool derived from the Merino sheep is one of the finest #wool #merino

How Is Merino Wool Made?

Wool grows in clusters on the body of sheep, and it is elastic in nature. We determine the quality of wool based on the amount of “crimp” it possesses. Crimp is the number of bends that the fibre possesses per unit length. The more bends in the wool, the finer the crimp, the longer the fibre and better the spinning capacity.

What is Merino Wool?

One thing I've often experienced with traditional woollen clothing is a characteristic “itch”. This is caused by short fibres that constantly spub against our skin, making it pretty uncomfortable. Merino wool, however, is different. It has very fine crimp and a diameter less than 24 microns. If you've not heard of a micron before, then have a quick read of my previous article What Is A Micron? A diameter of less than 24 microns means that the fibres are long, making and therefore much softer. So much so, that it's much more pleasant to wear directly next to our skin. Because of this, merino wool is suitable for lightweight knits, as the base layer in sportswear and can also be blended with fibres like silk and cashmere. The premium varieties of Merino are extra-lustrous and have an exceptional hand.

As Merino fibers are longer than typical wool fibers, the fabric absorbs less water and is stronger. So, it not only stays dryer for longer periods, but is also naturally warm, as the air movement between the dead air spaces in the garment is increased.

Merino wool also helps to regulate body temperature, by drawing moisture away from the skin when we sweat. It is one of the few natural fibres that possesses this characteristic feature known as “wicking.” Again, this makes it an ideal choice for athletes and sporty-types. For a more in-depth look at moisture wicking, I found this great article. The wool is also hypoallergenic, anti-microbial, naturally fire-retardant and doesn't retain odours - so it's a great choice for children's clothing too.

Production of Merino Wool

Let's now have a look at the various steps involved in the production of merino wool, as it travels from sheep to shop.

Ball of Wool: What is merino?
  1. The process begins with shearing the sheep. The sheared fleece is sorted based on the quality of fibres obtained from different parts of the animal's bod. You might not have thought of this before, but the wool can vary depending on where it comes from. An area that is exposed to constant abrasion and damage is likely to grow very coarse and rough, where as, areas less exposed will be much softer. This sheared wool is then scoured in a series of cleansing agents including water, soap, soda ash and alkalis to remove dirt, grease and sand. This can be quite chemically intensive, but this varies depending on the manufacturer.
  2. The fibres are now in a tangled form and lumped together. “Carding” follows, where the fleece is passed through metal teeth that separate the fibres into continuous long threads and blends them into slivers in continuous groups to form a wool top. [caption id="attachment_2178" align="aligncenter" width="500"] ".[/caption]
  3. The next stage is spinning the top. I wrote a more detailed article on the benefits of twisting and spinning, which is worth a read if you haven't already. The spinning in this case is done by drawing out, twisting and binding the fibres to increase their length and strength. Either of the two following types of spinning processes are used:
    1. Worsted Spinning uses longer fibres to create tightly woven yarn of smooth texture.
    2. Woollen Spinning uses shorter fibres to create bulky yarns that are loosely woven.
  4. The yarn is now converted into fabric either by weaving or knitting. Weaving is usually performed using a mechanical loom to get a smooth, consistent fabric. Knitting involves interlocking loops to create the fabric. Different patterns can be produced by either method.
  5. The wool is then dyed and progresses to the “finishing stages.” These include “fulling” or immersing the fabric in water to interlock the fibres, “crabbing” or setting the interlocks and “decating” which protects it against shrinking. Once this stage is complete, the fabric is ready to be worked on and converted into designs.

The Different Types of Merino

While Merino wool is a type of wool, it can be produced by many different breeds of Merino sheep. Although the wool derived from these different sub-species will have different diameters, Merino wool consistently has a microscopic diameter that is no greater than 24 microns. These include the following.

Poll Merino

These pure Merinos are bred by mating poll rams with Merino ewes. The results are offspring that are large-framed and quick to mature. They do not have horns, which also make them a little easier to handle.

Fonthill Merino

This is a hybrid species developed in the 1950's by crossing the American Rambouillet merino rams with Merino ewes that have a fine-wool Saxon strain. The sheep yield good quality fleece and meat (which means that they are their wool is often a by-product), and they are also easy to care for.

Booroola Merino

This breed is characterised by it's extended breeding season and improved fertility. A Booroola ewe can have as many as 6 lambs during its lifespan, and multiple births are common. The fleece is dense and the sheep has thick, fine wool over its entire body. More details on this hybrid variety is available here:

Delaine Merino

Here we have a practical breed of Merinos that easily thrive on average farms. The sheep have smooth bodies with compact and densely packed fleece. The Delaine Ewes have a very long productive life, which is an additional desirable feature. To find out more about this type of sheep, visit:

Peppin Merino

This breed is renowned for being the favourite amongst Australian sheep farmers. The fleece is heavy and has a higher content of natural wool grease. It survives in drier locations and the large bulk of its frame renders it an excellent forager. 

Determining The Quality of Merino

The thinner the diameter of wool (micron), the finer and softer the fibre is. Although the wool derived from different sub-species will have different diameters, Merino wool consistently has a microscopic diameter that is no greater than 24 microns. Based on the diameter of the fibre, Merino wool is classified into the following types.

The thinner the diameter of wool, the finer and softer the fibre is. #wool #merino

Type Diameter in microns

Extra Ultrafine



16 – 17.5


17.6 – 18.5


18.5 – 19.5


19.6 – 20.5


20.6 -22.5



The Pros and Cons of Merino

Merino is undoubtedly a superior fibre; one that combines comfort and durability with softness and luxury. Another thing that I love about Merino is that it is an excellent all-year-round choice. Unlike other forms of wool that have to be stowed away in summer, Merino garments serve me even when the weather is warm. It is also gentle, and hence suitable for sensitive skin and even babies.

A disadvantage of Merino is that it unlike similar synthetics, it takes a while to dry. Apart from this, an issue associated with this variety of wool is the high price attached to it. The consolation is that, where merino wool is concerned, the higher cost is usually well worth it.

Merino Wool Booties: What is Merino Wool?

While we are discussing the disadvantages of merino wool, there's a relevant animal husbandry procedure called “mulesing” that is often associated with wool production, that I've got to touch on:

Animal Rights and Merino – The Alternatives to Mulesing

Domesticated sheep have layers of moist folds in their skin, which attract flies. They lay eggs in these folds, and the hatched maggots feed on the flesh of these animals. This is called flystrike. To avoid this, farmers cut the folds of skin from around the tails of the sheep, and this is usually carried out without anesthesia. It is undoubtedly a very painful procedure, and the RSPCA strongly condemns this routine procedure. Instead, alternative solutions are suggested to counter the issue.

Breeding trials can help alter the genetic traits and create hybrids that do not have wrinkles. Another solution is to use clips or injections on the skin in the area to cause the skin to fall off naturally and cause less pain. If mulesing cannot be avoided, farmers are advised to use a topical spray post mulesing, for pain relief. Flystrike can also be strategically attacked using blowfly control.

This only just touches on this area (it's quite a big topic with lots to cover!) so for more in-depth information on mulesing and the alternative procedures, have a look at the RSPCA website.

Merino wool is synonymous with higher quality, and now that we are aware of the incredible benefits of this fabric, we know why we should be slipping into Merino wool and enjoying it all-year-long!

We're adding lots more articles to our wool series. You can check out our first woolly article by Sam Grig: Wool Types -The Blue Faced Leicester.

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Merino is an excellent all-year-round choice. #Merino #Wool

Merino wool also helps to regulate the body temperature. #Merino #wool

What is Merino Wool? #Wool #Merino