Cotton.
Even in a manual treating of the weaving processes it is not foreign to refer succinctly to the cotton and the treatment it has undergone to fit it for use in a weaving shed. The manufacturer who has had experience in a spinning mill often finds the knowledge acquired there to stand him in good stead in the selection and use of the yarn. Our chief supplies of cotton are drawn from the United States of North America; next in importance, although far removed in quantity from the first-named, is East India, then Egypt, and lastly Brazil. Cotton is a fibrous vegetable substance, being the fruit of the cotton plant, a shrub of the Malvaceæ, genus Gossypium. There are several varieties of this plant, but the development of the raw material is the same in each. The plant attains its full height about June (this being about two months subsequent to sowing), and the bolls or seed pods are found to be ripening about the middle of July. These bolls, about 1in. diameter, are divided by membranous walls into three parts, containing three or four seeds each, covered with the thin transparent cylindrical fibres attached by one end to the seed.
As the fruit approaches maturity, these fibres lose their cylindrical form, becoming ribbon-shaped through the collapse of their walls, and at the same time each fibre twists on its axis, thus causing a sufficient pressure on the interior of the boll to burst it at the junction of the compartments in the outer casing.
FIG. 1.
FIG. 2.
FIG. 3.
FIG. 4.
FIG. 5.
FIG. 6.
After being left on the trees for some days, during which time the ripening influences are at work, increasing the convolutions and maturing the fibre—or exposed perhaps in the case of unfavourable weather to the damaging influence of rain, which stains the cotton, or intense heat which renders it brittle, or wind which fills the boll with sand or leaf—the cotton is picked. It is then passed through a gin, a machine which has for its object the separation of the fibre from the seed. This latter, which in medium-stapled cotton exists in the proportion of 2lb. seed to 1lb. fibre, is used up at the oil-mills—while the cotton is packed in bales of 4cwt. and forwarded to the sea-coast for export. The foregoing may be taken as a condensed description of the cultivation of cotton on an American plantation. In Brazil and Egypt the season is about a fortnight later; in India planting generally commences in July, or immediately after the dry season.
The raw fibre then is a ribbon-shaped filament with corded edges twisted with 300 to 800 convolutions to the inch; thus, although to the naked eye appearing quite smooth, under the microscope it has somewhat of a resemblance to the shape of a joiner’s auger.
[Fig. 1] represents a typical cotton fibre about 400 times the actual size, and [Fig. 2] represents its section. [Fig. 3] represents an immature or imperfect fibre, one which is more transparent, brittle, and weak than the ordinary fibre, with no tendency to take dye. The convolutions also are few and irregular. [Fig. 4] represents its section.
The longest fibre is the Sea Island cotton grown off the coast of the States, averaging 1-5/8 inches in length, and chiefly spun into 150’s to 400’s yarn, although for experimental purposes 2150’s have been produced from it. Egypt gives three varieties—brown, white, and Gallini. The first-named is commonest and is used for 50’s to 150’s wefts and twists.
The American States yield a comparatively clean and even-running cotton, the best variety being Orleans, of a mean length of 1-1/16 inches, used for 30/40’s T and 30/60’s wefts. Texas, though shorter, is from its strength used for warp yarn, while the numerous varieties classed as uplands or boweds are suitable for weft on account of their usual good colour and cleanliness. The difference between the white 60’s and 70’s wefts and brown ditto is that the latter is from brown Egyptian cotton.
Brazilian is a very harsh fibre about average length, and used for twists either alone or mixed with American.
The East Indian varieties are extremely variable in length, and also in relation to the quantity of weak fibres; the properties common to almost the whole being brown colour, and dirty and rough character of the cotton. It is chiefly used in Rossendale, Bury and Oldham for coarse counts.
In the medium trade the fibre is subjected to no fewer than nine processes (each different, and sometimes duplicated or triplicated) before it arrives at the form of even thread known as yarn. In the fine trade two or three additional processes are added.
PLATE I.—PLAN OF SHED. To face pp. 16 and 18.
The spinning department, to describe it briefly, consists of:—
1. Mixing the cotton in stacks to secure thorough blending of various qualities, and elimination of the unevenness present in different bales or parts of one bale. Then commence processes for cleansing, viz.:—
2. Opening or passing the matted pieces of the bales through a series of armed beaters having the functions of both separating the material into small flakes and removing the heavier impurities contained in it, such as sand and seeds.
3. Scutching.—In this process a wing beater, revolving at a speed of 11/1500 revolutions per minute, removes the remainder of the heavy dirt, delivering the material in the form of a lap or roll of cotton. This process is repeated.
4. Carding.—Here, by means of revolving cylinders covered with fine wire teeth, and combing the cotton against other cylinders or plates similarly covered, the light impurities—leaf, dust, short and weak fibres—are extracted, and the lap attenuated into a thin sliver, in which the fibres are laid in such a position as to be easily drawn parallel at the drawing process. These four kinds of cleaning machinery remove impurities and other matter foreign to the nature of cotton, to the extent of about 10 per cent., taking middling American cotton.
5. Combing.—The long fibres are here separated from the short, thus enabling a portion of the cotton to be used for spinning finer yarns than the bulk would spin. It is only in the mills spinning yarns above, say 80’s, that this process is found; in ordinary, the custom is to go direct from carding to
6. Drawing.—A simple process repeated for yarn up to 30’s, used three times up to 60’s, and four processes are used above this. The machine has for its object the levelling of the slivers, six of which are placed together and drawn six times the original length. When this has been repeated once or twice, the sliver becomes very even and silky in consequence of all the fibres having had the curl taken out and been laid parallel to each other.
7. Slubbing; 8. Intermediate; and 9. Roving.—These frames are all constructed on one principle, and have for their object the gradual diminution of the thickness of the sliver, which at these processes is attenuated so much as to require twisting to keep it from breaking at the succeeding process. An additional jack roving frame is used at mills making over 100’s yarn.
10. Spinning completes the object of all the former machines—i.e., to produce a level clean thread, free from unevenness in every respect.
Four sorts of machines are used for completing the attenuation—the self-actor mule, ring frame, hand mule, and throstle frame. The two latter are fast disappearing in consequence of the great improvements over the hand mule recently made in the self-actor mule, so as to spin fine counts up to 300’s, and in the increased output of the ring over the throstle frame. The mule is automatic in all its movements for spinning the yarn and winding it on the spindle in the form of a cop—i.e., a cylindrical coil of yarn, cone-shaped at each end. In this machine the spinning is intermittent—i.e., for a few seconds the different portions of the machines are engaged in drawing out the roving to the required fineness until about 64 inches have been spun, the slack being taken up by a moving carriage bearing the spindles, then a few seconds are employed in drawing back the carriage and winding the yarn on the spindles. The ring frame is a constant spinner, and as fast as the yarn is spun it is wound on a bobbin, while the necessary twist is put in by a traveller shaped [C] revolving round a ring. It will thus be seen that the ring frame is only suited for warp yarns, mainly in consequence of having to use a bobbin, which of course requires modifications in the shuttle and box of the loom, and even then is disadvantageous. The ring frame is suitable and preferable for warp yarn up to 40’s, where the spinner also reels, warps or weaves his own spinning. The mule spins both weft and twist. Throstle twist (or, as it is called when reeled or warped by the spinner, water twist) is generally admitted to be the evenest and roundest thread, ring twist being next best, and mule yarn inferior to both. Mule yarn, however, possesses an elasticity which neither of these can boast of.
From a consideration of spinning we arrive at a definition of the manufacturing processes.
Unlike the spinning which is carried on in a building five or six storeys high, the manufacture of cotton goods takes place in a “shed,” as much of the work as is possible being carried on on the ground floor. The weft yarn, or that which is laid transversely in the cloth, leaves the mule in the condition in which it is required at the loom, but the twist or warp yarn passes through several “preparatory” processes to fit it for the operation in the weaving:—
1. Winding—to take the yarn from the cop and place it on the warper’s bobbin.
2. Warping or beaming to wind the yarn from 400 or 500 bobbins to one large beam.
3. Sizing—i.e., covering the warp with an adhesive preparation to fit it for standing the strains in weaving.
4. Attaching the healds and reeds to the warp, called looming or drawing-in.
5. Weaving.
Each of these will be described more fully in succeeding chapters, and as in different districts different methods are employed, more especially in the sizing and beaming systems, the one chosen for most minute description will be the one used most commonly, although the other systems will be referred to.
The weaving mill—or, as it is termed, shed—requires description next. The general details of such a building will be more easily understood by referring to the annexed plan.
The most important point to remember in the arrangement of the rooms for the different processes, is to place each so as to require as little transit of material as possible. The engine, a condensing one of 110 indicated H.P., horizontal, is driven by the steam generated in a 30ft. by 7ft. two-flued steel boiler working at 120lb. pressure.
In the flue is fixed a set of economisers heated by the hot air and gases generated in the furnace, and through the pipes of which passes the feed water.
In the winding room are two 200 spindle machines (100 each side), keeping 12 winders employed. There are 3 beaming frames, 504 ends each. In the sizing department are found the usual becks and cisterns for mixing purposes, and one slasher sizing machine. It will be noted that the weaving shop has direct communication with the looming room where the beams are stored, and with the warehouse whence the weavers obtain the yarn, at the same time returning the manufactured material. There is also an outlet into the mill yard without passing through any other department.
In case of a new shed having to be built, many important questions present themselves for consideration. In fixing upon the site, the essentials for a suitable position are a foundation sufficiently damp and of such a nature as not to easily part with moisture, even in hot weather, so as to preserve that humid atmosphere so essential to good weaving, more especially where heavy sizing is resorted to; yet there must be no yielding, for it is of vital importance that vibration be reduced to a minimum, both in weaving, winding and warping, to avoid breakages of yarn.
As many readers will be aware, it is partially in consequence of this disadvantage being removed in mills entirely on the ground floor, and partially in consequence of the increased dampness thereby obtained, that such mills can obtain good results out of inferior yarns. A position in the neighbourhood of good workpeople is most important; such an advantage more than compensates for the increased rents, rates and other dues of a town as compared with a country district, for with inferior employés, inferior work, and therefore less advantageous prices and fewer orders, are a consequence, while the cost of production is increased. Good coal and water supplies are of importance, and are best obtainable in the vicinity of a canal, and if the district under consideration be a hilly one, it will be worth while considering how to be sheltered from that bête noir of a weaver, the east wind.
CHAPTER II.
WINDING AND WARPING, WARP YARN, WINDING FROM COP, BOBBIN AND HANK, BEAMING, SECTIONAL WARPING, BALL WARPING.
As has been previously mentioned, the weft yarn, when it leaves the mule, is in the requisite form for use at the loom, whilst the twist or warp yarn passes through at least three processes to fit it for the operation of weaving. The object of these processes is to coat the yarn with a layer of the adhesive substance necessary to protect it from the chafing in the loom, and, secondly, to coil the threads of warp upon a flanged roller evenly, so that they will unwind at the loom in a level sheet the width of the beam, and containing the requisite number of ends to make a cloth of desired dimensions. Bearing this object in view, it is not difficult to understand the three processes—winding, warping, and sizing.