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All You Need to Know About Wool

This is the next in a series of articles looking in more depth at the characteristics of different fibre and yarn types and how to care for them to keep them looking at their best for longer. This month we’ll explore all things wool.

What is wool?

Wool for hand knitting or crochet comes in many varieties. It is defined as “the fibrous covering of a sheep (Ovis aries)”. The earliest wool textile dates back to around 1500 B.C. although there is evidence that sheep were bred for their wool as early as 6000 B.C.

The wool trade became important globally in the 13th and 14th centuries and has remained so until relatively recently, and only declining since the advent of synthetic fibres in the 20th century. The value of wool was so great in the Middle Ages that the Lord Chancellor of the House of Lords in England was ordered to sit upon the “Woolsack”, a seat stuffed with wool. It was seen as the most precious commodity and wars were fought to protect its trade routes!

Types of wool and their uses

We love sheep here at KnitIQ! There are believed to be over 1000 different breeds of sheep worldwide, with around 72 in the UK and up to 60 in the USA. The end use of the wool from a particular breed of sheep depends mainly on three things:

  • The fibre thickness measured in microns (the smaller the number the finer the fibre)
  • The handle of the fibre
  • The staple length, or simply the length of the fibres

The unique combination of these will define what sort of yarn can be spun from the wool and whether it is soft enough to be worn next to the skin or fine enough to be used for hand knitting or crochet yarns and woven fabrics. Coarser, harsher fibres are only suitable for carpets or insulation.

Sheep are generally sheared once a year – usually in the early summer months, so they don’t overheat under all that wool! Some medium- and longwool breeds such as Romney or Cotswold can be sheared twice a year, because their wool grows very quickly.

Lambswool is taken from the first shearing of a sheep when it is approximately 6-7 months old. It is the softest and finest wool that the sheep will ever produce. It has a short staple length of around 5 cm and is good to use in baby and children’s clothes or toys, because it is so soft.

Merino Wool

The merino sheep originated in Spain and produces some of the finest wool in the world at less than 24 microns, with superfine merino at less than 17 microns - for comparison, a human hair is 75-100 microns thick - it is made into premium yarns and can be used for anything from items that will have direct contact with the skin to cosy blankets. The staple length is quite short at around 6.5cm -10cm but it has a springy handle.

Medium Wool Breeds

Medium-wool breeds are generally dual purpose sheep, reared for both their meat and their wool. Romney falls into this category and is very popular worldwide. Its fibres are 10-20cm long and around 32 microns in diameter. It is a great all-rounder and is often recommended as a good fibre to start with when learning to hand-spin yarn.  

Long Wool Breeds

Longwool or lustre breeds include Blue Faced Leicester (BFL), Cotswold and Teeswater. The longer staple length of 15 - 30 cm gives a smoother, more lustrous appearance to the wool, and makes it less prone to pilling than lambswool or merino. BFL is often used for sock yarns in a blend with nylon to give it more durability.

Shetland Wool

Shetland wool comes exclusively from sheep native to the Shetland Islands. It is coarser at around 30 microns but bouncy with a staple length up to 12cm. It is great for making warm garments like hats and gloves. It is available in up to eleven distinct natural shades and a huge variety of dyed colours, making it most suitable for colourwork patterns. The dyed shades have often been fibre dyed and then several different colours blended together to form a yarn with different flecks of colour in it, reminiscent of the Shetland landscape. It is also a great choice for making garments or items that need to be steeked as the yarn is quite sticky and will not unravel easily.

One of our personal favourites here in the KnitIQ office is the Herdwick sheep – unfortunately its wool has a harsh handle and is generally 35+ microns diameter so it is really too coarse to knit garments from. It makes lovely carpets though and has such a cute face! What’s your favourite sheep?

If you want to learn more about British sheep breeds then the Woolist website is a good place to start: or have a listen to the WoolWork podcast:

Production and benefits of wool

Wool is naturally anti-microbial – so even handknit wool socks don’t need to be washed after every wear – just shake them out and air them overnight and then they are good to go again the next morning! It can both absorb and repel moisture at the same time – making it both breathable and water repellent – so perfect for the British climate! It is biodegradable and contains nitrogen so can be used to fertilise the soil. Wool is also insulating and naturally flame-retardant so is often used in upholstery, carpets and workwear uniforms. It is just an amazing fibre, full stop!

Wool for use in hand knitting/crochet yarns is first scoured to remove impurities such as “suint” – sheep sweat and bits of straw. Unfortunately this also removes most of the lanolin as well which helps to make the wool soft and maintain its waterproof properties which keep the sheep dry and warm out in the fields under its fleece.

Lanolin is often used in cosmetics and to treat skin conditions, and is also added to wool wash detergents such as our KnitIQ No-Rinse Delicate Wash.

One of the issues with wool is that the surface of the fibre is covered in scales. If the fibres are agitated, the scales become entangled and matted – a bit like backcombing your hair. If the fibres are heated as well as agitated, they will shrink and felting will occur. Sometimes this is desirable - for instance if you are making felted slipper socks - but generally we don’t want this to happen.

What is superwash wool?

Superwash wool was developed in the 1970’s by treating the fibre either to an acid bath that removes the scales from the surface, or coat it in a polymer that covers it and protects it from becoming entangled and felting.

It also means that superwash wool can stretch more than you might expect! In our experience it is a really good idea to make, wash and block a gauge swatch before starting your project to see how it behaves. Although there is nothing wrong with oversized cardigans….

New, more environmentally conscious methods of making wool washable are also continuously developed, for instance using enzymes to remove the scales or biodegradable substances to coat them rather than polymers derived from plastic. Check with your favourite yarn supplier to see what they are up to!

What happens after the wool is cleaned from 'suint'?

The fibres are then carded, which means they are passed between two surfaces covered in spikes or pins. This mixes them together to form a sliver or roving which can then be spun into a yarn by adding twist to it. It produces what is known as a woollen spun yarn, and is used for fibre types with short staple lengths.

Wool fibres with longer staple lengths may undergo another process called combing – this removes any shorter fibres, straightens the fibres out and makes them run parallel to one another. They are then drawn out into a fine roving and spun into yarn known as worsted-spun. This yarn is smoother and more lustrous than woollen-spun yarn. It is not to be confused with worsted-weight yarn which is a specific weight/thickness of hand knitting yarn.

What is ply in wool?

Once the yarn has been spun it is then often plied – so two or more yarns are then twisted together to form a 2-ply, 3-ply, 4-ply, 8-ply etc. yarn. This makes the finished yarn stronger than its single ply equivalent. This is where the term “4-ply” comes from that is often used to describe a fingering-weight yarn, although, confusingly, some 4-ply weight yarns are actually only made from two plies, e.g. Spindrift from Jamieson’s of Shetland.

A no-nylon sock yarn has a higher twist level inserted in spinning to make it stronger and less prone to wearing into holes. Similarly, a 5-ply Guernsey yarn is a similar weight to a 4-ply yarn but the extra ply makes the yarn more dense so it knits up into a windproof and waterproof fabric used for ganseys.

How to wash and block your woollen items

Remember to always check the ball band to see what the yarn supplier recommends. With any wool or wool blend, however, we recommend to hand wash where possible as this will prolong the life of your garment – especially if you use a gentle liquid detergent like Knit IQ No Rinse Delicate Wash. Our gentle formula contains lanolin to help protect the wool fibres and keep them soft for longer.

Keep the water lukewarm and be careful not to agitate your garment too much or to twist and wring it out – just gently squeeze out excess water. This will help to minimise felting and shrinkage. We also recommend to dry your item flat rather than hanging it. Because wet wool in particular can get quite heavy and 'grow' with gravity making your work look saggy once dried. KnitIQ Blocking Mats are an ideal surface to lay or pin out your washed item onto and let it dry in shape.

And if you do decide on blocking, wool performs best when it is wet blocked. It can be stretched out and blocked quite aggressively and will hold its blocked shape if pinned out and left to dry completely. For step-by-step details on how to wet block your item – see our previous article HOW TO WASH WOOL AND CARE FOR YOUR KNITWEAR – the basic procedure is the same!

For a quick freshen up between washes, or if you can’t wait to show off your finished article, wool can also be spray or steam blocked. You can mix a pump of KnitIQ No-Rinse Delicate Wash with the water you fill into the spray bottle and spray the item lightly before blocking. Or simply pin it out onto your preferred KnitIQ Blocking Mats and then lightly steam with either an iron or a steamer using a delicate fabric guard attachment. Be careful not to directly contact the fabric surface or to scald yourself!

Finally, please do continue to tag us in your pictures and social media posts – let us know what your favourite sheep breed is!