All about Wool: Composition, Content and Characteristics

(Newly sheared Shetland fleece - April 2006 -Nier Lakes Shetland Sheep ).

For my Master spinner class, I have been reading up on wool. It never ceases to amaze me that I have been spinning for over 10 years, and never really gave any of this much thought. It just didn't seem important at the time...

I know, I know. What was I thinking?

But hey, I am reforming myself.  So I have been plowing through a few books, and here is what I have found thus far.

• Wool is a natural insulator and can protect from temperature extremes of both heat and cold.
• Wool can absorb up to 30% of its weight without feeling damp.
• It is more flame resistant than other fibres. It will not flare, melt or stick to the skin.

Okay that's pretty basic stuff. But here are a few things I really didn't know:

• Each fibre follicle is composed of scales. When you rub your finger from the tip to the base of the fibre, it is rough. When you rub from base to tip, the fibre is smooth. This is highly relevant when preparing fibre for a woolen vs worsted yarn.
• Fibre scales generate heat and dirt away from the sheep's body (so that's why fleece always looks so clean and pretty on the inside!) The scales also play a major role in wool shrinkage.
• Long wool fibres have long thin scales with very little overlap. This makes them smooth and lustrous.
• Fine wool fibres have an irregular scale surface, and this reflects more light. This makes the fleece less lustrous, but brighter in appearance.
• Fibres that have medulla (air filled cells in the centre core) show up as being hairy and coarse. They do not dye readily and are generally undesirable in a handspinners fleece. "Hairy" sheep breeds  are often used for meat.
• Each fibre sits in a tube called a follicle. There are 2 types of follicles. The primary follicle which has a sweat gland, and the secondary follicle which doesn't. Each sheep breed has a standard ratio of primary sweat glands to secondary sweat glands. The Lincoln sheep ratio is 4:1. The Merino sheep ratio is 20:1. (Ahh! so that's why merino is such a greasy fleece!)
• Fibre fineness is determined by the micron count (a measurement used in Australia and New Zealand), which ranges between 10 - 80.  A micron is one / millionth of a metre.  Each sheep breed has a standard micron count. The lower the micron count the smaller the diameter of the fibre ( and therefore the finer the fibre). These are usually best for handspinning purposes. In Britain and the United States, fibre fineness is measured by the Bradford count. This is based on the maximum number of skeins (each 560 yards long) that can be spun from one pound of combed top. The Lincoln sheep has a Bradford count of 36 - 40 (or 38 - 36 microns). It is suitable for projects such as rugs, upholstery and rug making.  The Merino sheep has an average Bradford count of of 60 - 72 (or 24 - 18 microns).It is suitable for fine knitting type projects, such as baby clothing and shawls.
• Staple length is an important consideration when planning your project, and considering the best way to prepare your fibre for spinning. Short staples are suitable for carding, and woolen spinning. They make soft poofy yarns.  A long staple length is more appropriately prepped by combing, and spun worsted. This would result in a flatter, smooth yarn - which is nice for pattern work (think Aran worsted yarns)
• Crimp is the wavy pattern in the wool staple (the length of the lock). It gives the fibre its elasticity. It also suggests the amount of twist that should be added to the fibre when spinning.

That's all for today. Now I have to put the theory into practise and get spinning!

Sources:

• Fleece in Your Hands by Beverly Horne
• Encyclopedia of Handspinning by Mabel Ross
• In Sheep's Clothing - A Handspinner's Guide to Wool by Nola Fournier and Jane Fournier

Comments

[Valerie]

Wool is amazing stuff isn't it? That is a BEAUTIFUL shetland fleece you have there!! BTW...I think you've mixed your micron and Bradford Count numbers in the part about fiber fineness. At first I thought is was just the old metric vs. English thing rearing it's head (as it ofren does across our border < For fun..check out http://www.ansi.okstate.edu/breeds/sheep/ to look through the sheep breeds. It's a nice online supplement to the Fournier's book.
For a nice comparison of Bradford and Micron count, check out: http://www.digitalburn.net/clients/bcsba/info.php?name=Fleece%20specifications&type=fleece

[sheepless]

Hi Val - thank you for pointing out the Bradford count info - funny this exact topic just came up on a spinning list a belong to - I never put the two together...duh!I have updated my info

[Cheryl]

I'm glad you posted the info about fiber fineness, that's an area that's been a little confusing for me, thanks for shedding some light on it! And thanks for listing your sources, I'll be checking those out!