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Four factors are considered in the classification of wool
fibres; count, staple length, crimp and lustre:
Count: The traditional classification of
wool fibre was done using the 'Bradford' Count which represented
the greatest length of yarn that could be spun from 1lb (454gm)
of the wool fibre. The fibre was spun into yarn which was
then wound into hanks of 560 yards (512 metres), and the number
of hanks produced gave the count for that fibre. A spinner
can therefore spin 1lb of 56 count wool into 56 hanks each
containing 540 yards of yarn, or nearly 17.2 miles (28.5Km).
The higher the Bradford Count, the finer the wool fibre.
Typically a down fleece used by hand spinners has a Bradford
Count of 40 to 56. Merino, the finest of wool commonly available
has a count greater than 60 and can go as high as 110. The
finer the fibre, the more easily it will turn to felt with
exposure to damp, heat and alkalis such as soap. The count
is not consistent across a fleece with the finest wool at
the neck and the coarsest at the britch and belly. Commercially
prepared fibres will have been sorted to give a consistent
count throughout. Fibres are now more commonly classified
by the micron reading for the diameter of the fibres rather
than the Bradford Count; a conversion table is given at the
bottom off the page.
 Staple:
The length of the wool fibres or 'staple' varies a little
across a fleece, from shorter at the neck to longer in the
middle section. The staple length (or Hauteur) of the wool
fibre determines how easily it can be spun into a yarn. Fibres
with a staple ranging between 8cm-12cm are the easiest to
hand spin, typically these are found in the downland breeds.
Longer staples such as Devon Longwool, shown in this image,
has a 20cm staple length and is quite coarse and so is used
for making strong rug warp as well as Dolls Hair. By way of
contrast in Wensleydale the staple can be up to 35cm, and
with a high Bradford Count is spun for fine strong yarns typically
used in suits. Long staple fibres require skill in hand spinning,
using a long drafting zone and relatively little twist if
an even finish is required. Shorter staples such as Black
Welsh Mountain, which can be only 5cm, require a high twist
to create a viable yarn.
 Crimp:
The crimp is the number of waves along the length of the wool
fibre. Fibres with high crimp, 4-6 per cm are generally finer
(i.e. have a higher Bradford Count) and therefore can be spun
to a finer yarn. They perform well for woollen spinning as
they trap air in their structure to give an excellent insulation.
A fibre with a high crimp is less suitable for worsted spinning
as it is difficult to compact the fibres enough to give the
drape associated with worsted spun yarns. The commercially
prepared Bluefaced Leicester fibre, shown in this image, has
quite a high crimp and is ideal for woollen spinning. It has
a Bradford Count of 50 and a 15cm staple length. The Devon
Longwool mentioned above has no crimp and is used for worsted
yarns used in belts.
Lustre: At a microscopic level the surface
of wool fibres is seen as covered with fine 'scales'. In the
fibres of some sheep breeds, such as Wensleydale and Massam
the scales have a very smooth and shiny surface to produce
an effect known as lustre, these respond well to dyes giving
a strong clear colour. Other breeds such as Cheviot have a
rougher and therefore duller surface and dyes show as a matt
finish. In general a duller fibre will felt more easily.
Wool Counts are now measured in microns which represent the
wool fibre diameter. 1 micron equates to 0.001mm, therefore
the lower the Micron figure the finer the fibre.
| Here are approx. comparisons: |
| Micron Measurement |
Bradford Count |
| 19 |
70 |
| 20 |
68/66 |
| 21 |
64 |
| 22 |
62 |
| 23 |
60 |
| 25 |
58 |
| 28 |
56 |
| 33 |
50 |
| 35 |
48 |
| 37 |
46 |
The following web sites contain further information about
wool fibre production and sheep breeds:
Browse for: fibres
Please note: Fibrecrafts is not responsible for the content
of external websites
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