Spinning
The spinning of cotton yarn (thread) is typical of all the fibers. The stages may be divided into—
1. Opening and picking.
2. Carding.
3. Combing.
4. Drawing.
5. Spinning.
Picking and Carding
The picking and carding have for their object the removal of all foreign substances with as little damage to the fiber as possible. The foreign substances in cotton are sand, dirt, pieces of leaves, seed, husk, etc., which have become mixed with the fiber during the process of growing, ginning and transportation.
Cleaning
The cotton bales are opened and thrown into the automatic feeder which carries up a layer of cotton on a spiked apron from which it is removed by a rapidly revolving “doffer” underneath which is a screen which catches some of the dirt. It is next fed between rolls in front of a rapidly revolving blunt-edged knife which throws out more of the dirt through a screen. There is a suction of air through the screen which helps remove the foreign substances. The cotton passes through several of such machines, being formed into a soft web or “lap” which is wound into a roll.
Carding
The carding machine further cleans the fibers and lays them in a general parallel position. From this machine the web is formed into “sliver,” a loose rope of cotton fiber about two inches in diameter. This is received in circular cans.
Combing
The combing is omitted for short fiber cotton, but is used in worsted spinning and with long staple cotton to remove the short fibers. Cotton to be used for making yarn suitable for hosiery, underwear, sewing thread, lace, and for very fine cotton fabrics is carded.
In drawing, from six to sixteen “slivers” are run together and the fibers drawn out in several stages until the soft rope is about an eighth of an inch in diameter, called “roving.” This tends to get rid of any unevenness and makes the fibers all parallel. From this machine the roving is wound on a bobbin ready for the spinning frame.
Spinning
The spinning frame may have a hundred spindles or more, each one of which is drawing out its supply of “roving” to the required size of yarn and giving it the twist necessary to bind the fibers together. The yarn to be used for the warp is given a harder twist so that it may be strong enough to stand the strain in weaving. The yarn for filling is usually left soft.
The yarn for warp is now usually given a coating or “sizing” of starch and gums so that the thread may not become unwound and break during weaving.
The process of spinning is much the same for flax and for wool, although somewhat differently constructed machines must be used. Flax is usually spun wet.