Wool Fibre Quality

When the wool sorter classifies wool he rapidly assesses such factors as fibre fineness,crimp,length,scalines,handle,and lustre,but the most important characteristic which is judges is fineness.

Fineness

Although the mean fibre diameter is an important component quality,an indirect method of expressing the fibre fineness is used.Other things being equal,a finer fibre can be spun into a finer yarn.This being so,the original basis for assessing fineness was to estimate the finest yarn that the wool sample could produce.

For example,a sample of wool could be classed as 58s, the inference being that the spinner could make a 58s worsted yarn from it.The developments in spinning techniques have enable the spinner to produce finer counts than the quality number would suggest but,nevertheless,the original standards have been adhered to.The three main class of wool are Merino,sometime called Botany,with quality numbers 60s to 100s,36s to 58s and Carpet,up to 36s.
The American standard links the measurement of wool fibre diameter by the projection microscope and the grade.

Crimp

A feature of the wool fibre is its 'crimp'or waviness.

Average diameter µ (min.)	Average diameter µ (max.)	Grade
17.7 19.2 20.6 22.1 23.5 25.0 26.5 27.9 28.4 31.0 32.7 34.4 36.2 38.1	19.1 21.5 22.0 23.4 24.9 26.4 27.8 29.3 30.9 32.6 34.3 36.1 38.0 40.2	80s 70s 64s 62s 60s 58s 56s 54s 50s 48s 46s 44s 40s 36s

Researches has shown that some form of relationship exist between the crimps per inch and the fibre fineness, the finer the fibre the greater the number of crimps per inch.The wool sorters judgment of fineness and his subsequent estimate of the quality number is probably influenced considerably by this knowledge.

Length

When the length of wool fibres is considered it is found that in the mai sorter wools are fine and the longer wools coarse,a reversal of the order for cotton fibres.For worsted yarns,fibres which are long,fine,and uniform in length are disirable,and because in most of cases a combing process is used in their preparation,wools suitable for worsted yarns are termed 'combing' wools.For woollen yarn where a softly handle is wanted and where the fibres are carded,the shorter wools are chosen and referred to as 'clothing' wools

Ellipticity

The cross-section of wool fibres are nearly circular,but have varying degrees a combingof ellipticity, the amount being expressed as the 'contour ratio' the ratio between the major and minor axes of the fibre contour.Some authorities are of the opinion that the nearer this ratio is to unity,i.e. the more circilar the fibres,the better the wool will spin.
Wool quality is big subject and these notes are,of necessity,brief.