Properties of Wool

The properties of wool result in a material that is multifaceted and multipurpose. It is one of the few natural products readily available that can be made use of in a myriad of ways. From providing the sheep with a house on its back to providing us with insulating wool garments, art products and tree mulches.

The specific wool characteristics vary from breed to breed. (The variation is why we have a grading system). To help further understand the properties of this unique fiber we'll define the lingo, and the various qualities that make wool what it is.

Fibre
Fibre is an individual strand of wool, just like a single strand of hair from your head.

Staple
A staple is a cluster of many, many fibres, like a lock of hair.

Fine or Coarse
Fibres can have varying diameters according to the breed of sheep and type of wool. Like human hair, on some individuals the hair is fine (smaller diameter) and on others it is very coarse (larger diameter).

Wool can withstand a lot of wear and tear without the fibres breaking but the fineness or coarseness of the wool ultimately determines its end use. The diameter of the fibre accounts for the durability of wool.

Crimp
Each individual fibre is crimped (picture corrugated cardboard) and the crimp is easy to see in the collective staple.

The crimp varies according to the breed of sheep. Typically if the individual fibres of wool are fine the crimp will be fine. If the crimp is fine it means there are more crimps (ridges in the cardboard) per length of fibre than if the crimp was heavier.

One of the great natural properties of wool is that it is naturally woven by longer fibres that run across several staples thus holding the fleece together. This is why it is possible to throw the fleece after shearing without it falling apart like hair would. Throwing the fleece is the act of tossing the wool clip up and out to spread it onto a table for skirting (removal of dirty or damaged wool pieces).

Count
If you are looking at yarns you will come across the term 'count'. The count is the spinning quality and is determined by the diameter of the fibre. Since it is not feasible to measure the diameter of individual fibres, the crimp as visually seen in the collective staple is used to make an assumption on the spinning quality.

Length
For spinning, wool has to have length. Length is a measurement of the staple without stretching out the crimp. Fine wool of considerable length will be a highly sought after product for spinning.

When processed wool is stretched at several stages. The amount of crimp determines how much the piece of wool can stretch and this is a very important feature. The more stretch wool can give the tighter it can be when returned to original length.

When talking of the properties of wool what all this means is that a shorter staple with deeper crimp is preferred over a longer staple with flatter crimp that will not stretch as much.

The length of the fibre is one of the properties of wool that will vary significantly from breed to breed. The fibre length plays a role in determining if the wool can be combed or carded. The longer fibres are suitable for combing while the shorter ones are suitable for carding. Wool that is combed will serve a different purpose than the shorter varieties that are carded.

Brightness
A high percentage of raw wool is whitish in color with a yellow tint. The brightness of wool refers to the amount of yellow tint that is present or absent. A bright wool will have little yellow tint in it and will fetch a higher price.

A small percentage of sheep are capable of producing naturally dark colored fleeces that are grey, brown or black. On the general market the white wool is preferred because it can be readily dyed to subtle shades of color. It is considered a defect to have a white fleece with colored fibres in it and these fleeces are seperated and sold as grey fleeces.


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