A wool staple is a cluster or lock of wool fibres and not a single fibre.
For other textiles, the staple, having evolved from its usage with wool, is a measure of the quality of the fibre with regard to its length or fineness.
The staple strength of wool is one of the major determining factors of the sale price of greasy wool.
At least 40 staples must be measured to in order to conform to the Australian Standard. Wools under 30 newtons per kilotex are considered tender. Currently wools over 40 newtons per kilotex are preferred and attract a premium. Seasonal conditions or the health of the sheep may influence the soundness (strength) of the wool.
The staple length of the wool is the length of the staple, and highly correlated with mean fibre length in the top (hauteur).
Staple length generally determines the end use of wool, that is, whether it will be used in weaving or knitting. The longer wools, generally around 51 mm and longer and called combing types, are processed to worsted yarn. Short-stapled wools are more profitably used in the woollen section where high-grade material may be produced from superfine wool.
The Australian Standard requires that a sale lot has a minimum of 55 staples measured with the average calculated and produced. The variability of this measure is reported as the coefficient of variation (CV%).
- "staple, n.3". OED Online. June 2011. Oxford University Press