The spool cotton of to-day is of a different grade from that made before the sewing machine came into general use. The early thread was but three cord, and contained such a large number of knots, thin places, etc., that it could not be worked satisfactorily on the machines, so manufacturers were called upon to produce a thread that would be of the same thickness in every twist. This was effected by making the thread of six cords instead of three, thereby producing a smoother and more uniform strand.
Manufacturing Processes. The raw cotton for the manufacture of thread must be of long staple. If the fiber is short the thread made of it will be weak, and hence unsuited for the purposes required of it. Ordinary cotton is not adapted to the manufacture of the better grades of spool cotton on account of the shortness of its fiber. Egyptian and Sea Island cotton are used because they have a much longer fiber and are softer in texture. The raw cotton comes to the factory packed in great bales, and is usually stored away for some months before it is used. The first step in the conversion of the bale of cotton into thread consists in giving the fiber a thorough cleaning. This is accomplished by feeding it to a series of pickers which pull the matted locks and wads to shreds, beat out the dirt and seeds, and roll the cotton in the form of batting upon cylinders until it issues from the finisher lap machines as a downy roll or lap.
The lap of cotton then goes to the carding rooms, where it is combed into parallel fibers by means of a revolving cylinder covered with fine wire teeth, sometimes 90,000 of them to the square foot. On leaving the carding machines the lap has become a gossamer-like web thirty-nine inches broad. This web is next passed through a small “eye” which condenses it into a narrow band about an inch in width, known as the sliver. By this time the fiber has been so drawn out that one yard of the original lap has become 360 yards of the sliver. The sliver now looks almost perfect, but if it were spun it would not make good thread. It is necessary to lay every fiber as nearly parallel as possible, so that there will be an equal number of fibers in the strand per inch. Besides this, the remaining dirt and short fibers must be removed and the knots and kinks in the fibers straightened out. To accomplish these objects the cotton must be “combed.” First, the slivers are passed through several sets of rollers, each set moving faster than the preceding, so that the strands are drawn out fine and thin. In this condition the cotton passes to a doubling frame, and from thence to the lapping frame, a device combining six laps into one and drawing the whole out into one fine, delicate, ropy lap.
WARP ROOM
1. Beam on which the warp is wound.
2. Warp.
3. Creel.
4. Spools in the creel.
The comber now takes the lap and combs out all the impurities and short fibers, at a sacrifice of about one-fifth of the material; next, it combines six of these fluffy combed rolls of fiber into one. A number of these rolls are then drawn out by another machine twelve times as long as they were before and twisted together on a slubbing frame. This last drawing reduces the roll to about the thickness of zephyr yarn. After being further doubled and twisted, the yarn, or roll, is ready for the mule spinner, which accomplishes by means of hundreds of spindles and wheels what the housewife once did with her spinning wheel. The mule, however, does the work of more than 1,000 hand spinners and takes up much less space. On this machine 900 spindles take the yarn from 1,800 bobbins, and by means of accelerating rollers and a carriage draw out and twist it to the proper fineness for the size of thread wanted. Having passed through the complex processes of cleansing, combing, drawing, and spinning, the cotton is now in the form of yarn of various sizes, and the real work of thread making, which is a distinct art from yarn making, begins.
The thread-making process is briefly as follows: The yarn is doubled and twisted; then three of such yarns are twisted together, which give the six-fold combination for six-cord thread. For a three-cord thread three yarns are twisted together. After the twisting is completed the thread is reeled into skeins having a continuous length of 4,000 to 12,000 yards, according to the size, and is then sent to the examining department where it is rigidly inspected. Every strand is looked over, and any found to be defective are laid aside, so that when the thread is put on the market it shall be as perfect as care and skill can make it.
At this stage of the work the skeins of thread are of the pale cream color common to all unbleached cotton goods, and are technically known as “in the gray.” They therefore have to be bleached pure white or dyed in fast colors. The skeins, whether intended for white or colored thread, are first placed in large, steam-tight iron tanks and boiled. Here the thread remains subjected to a furious boiling for six or seven hours; when removed it is perfectly clean, but still retains the brownish gray color of unbleached cotton. It then goes into a bath of chloride of lime and is bleached as white as snow. The skeins are next drawn through an acid solution to neutralize the chloride. Another boiling, another bleaching, a bath of soapsuds, and the final rinsing, complete the cleansing and whitening process. Those skeins intended for colored threads are taken to the dyeing room and placed in tanks filled with suitably prepared dyeing solutions.