 Wool washing is a very laborious process because of the whimsical nature of the textile
Added: 10/26/2005 |
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Wool from a practical point of view
is by no means a simple body, but has complex physical structure. Fleece wool as it comes into the market is "in the grease", that is
ubwashed. The quality of the fiber
may be seriuosly injured if wool washing is omitted, it will dye unevenly, and manufacturing operations will expirience color bleeding, or decoloration.
Wool's composition in the raw state
is threefold. Thus there is the wool-yolk - what may be termed a
natural impurity; the wool fat, which is not only present in the yolk but also permeates the fibre and seems to give it its plastic and soft handle; and the cell structure proper of the fibre. Fleece wool comes into the market unwashed with all the dirt which gathers to the surface of the greasy wool; or it is
received as "washed" wool, the wool washing being done as a preliminary
to the sheep-shearing, or in some cases, it is scoured and is consequently stated as "scoured".
Where there is abundance of water and other conveniences it is the
practice to do wool washing or half-washing of sheep previous to shearing, and such wool comes into market as washed or half washed- fleece.
The surface of a fleece has usually a thick coating of dirt, and in the
case of merino breeds the fleece surface is firmly caked together into solid masses, so that in fleece without wool washing 30% of weight
may represent dirt, and about 40% the greasy suint which lubricates the wool, while the pure wool is not
more than one third part of the whole. Sheep washing appliences are
employed, the arrangement consisting
of a pen into which the sheep are
driven and subjected to a strong spray of water either hot or cold, which soaks the fleece and softens
the dirt. This done, they are caused
to swim along a tank which narrows
towards the exit, and just as they pass out of pen they are caught and
subjected to a strong douche of pure
water. They should then be kept on
grass land free from straw, sand etc., so that the wool may be sheared free from vegetable matter,
etc. After wool wasing, the wool of
a washed sheep is sufficiently dry
for shearing or clipping.
The wool washing which a fleece may
have received on the live sheep is not sufficient to avoid color bleeding in fabrics manufacturing.
Much depend on careful scouring. The
quality of the fiber may be seriously injured by treatment, while, if the wool is imperfectly
cleansed, it will dye unevenly, decoloration may happen, and the
manufacturing operations will be
unsatisfactory. The water used for
scouring should be soft and pure, both to save soap and because the
insoluble lime soap formed in dissolving soap in hard water is
deposited on the wool fibers and becomes so fixed that its removal is
a matter of extreme difficulty. Wool
washing machines ensure the passage
of the wool without lifting and "stringing", to obviate the mixing of wool grease, sand, dirt, etc., once taken out of the wool with that
wool again, to give time for the action of scouring agents, so that
neither too strong a solution nor too great a heat be employed.
Worsted yarn manufacture is done with the help of "water frame". In
order to obtain a sliver, which can
be satisfactorily spun into a typical worsted thread five or six
operations are necessary and one of them is back-wasing. The slivers
during their passage through the
preparing-boxes become sullied naturally, and in addition, owing to
the opening out of the locks of wool, dirt which was not "got at" in
the scouring now works out and further sullies the slivers. It is
consequently necessary to do wool
washing again, this being effected in what is termed a back-washing machine. The machine usually consists of two scouring tanks with
immersing rollers, drying cylinders,
a gill-box and oiling motion. To sum it up, those are wool washing methods that allow avoiding fabrics' color bleeding and discoloration.
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