Weaving

warp loom weft cloth shuttle threads heddles heddle thread separate

WEAVING is the art of forming cloth by the interlacing of yarn or other filaments in a loom. In weaving two kinds or sets of yarn are used, the warp and the weft. The warp consists of the threads of yarn which extend generally but not always in parallel lines from end to end the whole length of the web ; the weft yarn crosses and intersects the warp at right angles, and fills up the breadth of the web. The warp is mounted on the loom for weavMg, and into it the weft is thrown by means of a shuttle. Weaving is thus distinct from knitting, netting, looping, and plaiting, by all of which methods cloth may be made from yarns. Cloth also is prepared by felting, but in that operation the fibres are simply matted together without either spinning or intertwisting.

To appearance the varieties of woven cloth are endless; but these differences are only in part due to the method of weaving. The textile materials employed, the methods used in spinning and preparing yarns, the dye colours resorted to, and the finishing processes may vary indefinitely and so contribute to give variety of character to the resultant product. The complexities of the art of weaving itself are reducible to a few fundamental operations, which do not of necessity demand the most intricate mechanism. The gorgeous media:val textiles of which numerous examples remain were made in looms of primitive construction. For producing the Indian muslins of the present day with their marvellous delicacy of texture, and for the elaborate and sumptuous shawls of Kashmir, the weavers have only rude and simple looms. But patient and tedious handiwork in these instances is devoted to produce effects which, with the application of modern machinery, can be automatically secured with as great rapidity as in the case of the plainest fabric.

The series of inventions which have led up to the marvellously ingenious looms of the present day began with the invention of the fly shuttle, so called because of the rapidity of its motion, by John Kay of Bury in 1733. Previous to Kay's time the shuttle was thrown by the weaver's hand across and through the warp threads from side to side of the web. His invention brought the plain hand-loom practically into the form in which it continues at present ; and, as it forms the basis of all modern machinery, a description of its parts and working, and of the operations connected with plain weaving, may here be given. In accordance with the definition already laid down, plain cloth, such as an ordinary piece of calico or linen, will, on examination, be found to consist of two sets of threads, the one intersecting the other at right angles, with each single thread passing alternately over one and under the next. Such a web is produced by passing the weft thread over and under each alternate warp thread in the breadth of the loom, the warp threads under one shot of weft being above the next. To do this, and to beat or close up each successive weft thread so as to snake an even and sufficiently close cloth, necessitates a series of operations of which the following is an outline.

Warping. - The number of longitudinal threads which go to form the web will vary, of course, according to its breadth and to the closeness with which they lie together ; for fine webs several thousand warp threads, of sufficient length to form a web of many yards, may have to be laid parallel to each other. This is done in the warping frame, which consists of a large reel, set vertically, on which separate threads drawn from a range of bobbins are wound together in a spiral manner to the required length of the web. The yarns coming from the bobbins are brought together in a heck, which is made to slide up and down a guide post as the reel or warping frame revolves, and thus it delivers to the reel a band of thread which winds up and down the reel spirally by the rise and fall of the heck. Supposing 100 "ends" or warp threads are being reeled from bobbins, and. 1000 ends of warp are required in the web, then the full lengths wound on the reel must be repeated upward and downward ten times. At each end of the warp the threads are, by a mechanical device in the heck, made to intersect alternately, forming leashes which are, when taken from the reel, separately tied up, and thus aid in maintaining the parallelism of the ends when they are bundled up. Such a bundle of warp when required for weaving is taken in hand by the beamer, whose duty is to spread the threads evenly and wind them on the warp beam, spreading the ends in the order in which they are to appear in the woven fabric, and giving them about the breadth of the web. Cotton warps are wound direct from the bobbins on the beam, there being a mechanical arrangement in the warping machine which stops its motion when any thread breaks, or when a bobbin is exhausted. The contents of several beams filled from bobbins may be required to be rewound together on a single beam to supply the requisite quantity of ends for a web.

Raise Weaving. - The warp beam thus filled is laid in the loom (fig. 1), and the ends of warp are then separately drafted or drawn through a pair of heddles or healds. The essential features of the WEAVING 537 heddle are the eyes, loops, or mails through which the warp is threaded, one end of warp only passing through any mail. This eye or mail is placed in the heddle half-way between an upper and a lower wooden sheaf, over which pass the heald threads or between which extend the wires on which such snails are supported. The distance between the mails and the lathes at each end must be sufficient to allow of that opening or "shedding" of the warp which it is the function of the heddle to secure. Through the mails of one heddle each alternate end of warp is drafted, and the remaining ends are passed similarly through the other. Thus each heddle receives every alternate thread across the whole breadth of the warp. From the heddles the ends are carried through the reed (fig. 2), which is the ultimate distributor of the warp, and the instrument by which the weft is beaten up and closed in weaving. It consists 537 of an oblong narrow frame filled with fine strips of cane or of flattened brass or steel wire, these strips being placed in fine comb-like order more or less closely together, up to as many as 120 strips or "dents," or even more, per inch; two or more ends are passed through each slit of the reed, which is fixed in a "lay" or "batten," a suspended frame for moving the reed backward and forward in beating up the weft. On the lower part of the batten a ledge projects, which forms the "shuttle race " for carrying the shuttle in " picking" from and to the shuttle boxes at each end of the lay. From the reed the ends arc carried forward and fastened to the cloth beam, and now the warp is ready for the weaving operation.

The three essential movements in weaving are (1) the "shed-cling " or dividing of the warp threads to permit of the passage between them of the shuttle containing the weft ; (2) the " picking" or shooting of the weft ; and (3) the " battening " or beating up of the weft. The shedding motion depends upon the heddles, which are corded or attached to a pair of treadles worked by the weaver's feet. Each treadle is connected with the heddles above and below by a system of levers or pulleys, so that the depression of one treadle while it raises one heddle depresses the other, and thus the opening or shed is made in the warp, one-half - consisting of alternate threads - being raised, the corresponding half pulled down. The weaver then with the left hand pushes the lay or batten back towards the heddles, till a sufficient portion of the shed is brought in front of the reed, and the depressed ends lie just over the shuttle race. A clear way is thus provided for picking or shooting the shuttle, which is done with a whipping jerk of the picking stick held in the right hand. This pulls the cord attached to the picker and projects the shuttle from one shuttle box into that at the opposite end of the lay. The lay is now drawn forward with the left hand, and the reed combs and beats up the weft thread. Treadle number two is next depressed and thereby a new shed is formed, the last made pick or shoot being enwrapped between the intersecting warp sheds ; the lay is again thrown back, the pick of weft is shot and beaten up, and so on in regular succession (see fig. 3).

In plain weaving it is possible to produce stripes by the use of bands of coloured warp, and cheeks where both warp and weft are particolonred. In the latter case shuttles, or at least cops, equal in number to the different colours of weft required, must be provided. It is obvious that the repeated changing of shuttles, and still more the withdrawing and replacing of cops in weaving with frequently changing weft, would occasion great loss of time. To avoid that, and to provide for the use of different coloured wefts, or of wefts of various counts, the drop box was invented, a device by which two or more shuttles can be successively used in any order desired. The drop box, and its numerous subsequent modifications of circular and other change boxes, consists of a series of compartments or divisions in the shuttle box, each made to hold a separate shuttle. These several compartments are by mechanical agency brought in line with the shuttle race in the order in which the changes of weft picks are necessary.

Twill Weaving. - So long as only two sets or leaves of treadles are used in a loom very little in the form of a pattern can be produced, seeing no variation can be effected in the alternate raising of each heddle. To a limited extent a corded. surface may be produced by passing two or three warp ends through each mail, and by throwing two or three picks of weft between each shed. But for effective figure-weaving there must be numerous possible variations of shed ; and that is secured first by increasing the number of heddles in the loom. Thus with three heddles alone it is possible to effect six combinations of shedding, and as the number of heddles is added to the variations of possible shedding increase in geometrical ratio. But the number of treadles which can be corded up to separate heddles is in practice limited, and therefore only simple twill patterns are for the most part woven with treadles and heddles. A twill is a cloth in which the warp and weft do net intersect alternately, but where the warp predominates on the one side and the weft on the other. The simplest of all is the three-leaf twill, in which the warp passes over two and under one weft thread, and vice versa, in regular succession, giving the appearance of a succession of diagonal lines on the surface. Regular twills of from four to eight leaves are woven in the same manner, the weft rising over each fourth to eighth warp thread as the case may be. Many variations and combinations are possible in connexion with these regular twills. For example, they may be combined with plain weaving : a cashmere twill may be made, - that is, a four-leaf combination, in which the weft passes alternately over and under two warp ends, and two picks are shot for each shed. Further, zigzags, lozenges, squares, and other geometrical designs can be produced by reversing the order of the treading, and thereby causing the twill to run in different directions. The diagrams, figs. 4 and 5, show two arrangements of a four-leaf twill, the first being a regular twill and the second a dimity, the dark squares representing the point at. which the weft rises to the.

537 surfaces. Satin or broken twills are those in which the warp threads are not intersected by the weft in regular succession, but only at intervals, and thereby the smooth continuous surface characteristic of satin and damask is secured. Common satin and double damask are eight-leaf twills, the order in which the weft rises being shown in the diagram, fig. 6. Rich satins may consist of sixteen to twenty leaf twills, the weft intersecting and binding down the warp at every sixteenth to twentieth pick as the case may be. Satins are usually woven with the face of the cloth downwards, because in weaving, say a sixteen-leaf satin, it would be necessary were the 537 surface upwards to keep fifteen heddles Fig. G.

raised and one clown, whereas, with the face of the cloth under, only one heddle has to be raised at a time.

Figure Weaving. - Only a limited number of heddles can in actual working be attached each to a separate treadle to be under the control of the feet of the weaver. But to produce a complicated and irregular pattern a large number of different sheds of warp must be provided, and to secure with promptitude and certainty such manifold and complicated sheddings many of the most elegant and ingenious devices ever applied to mechanism have been invented. Before invention culminated in the Jacquard apparatus the draw loom or draw-boy loom was the machine employed for making figured patterns such as damasks. In it each separate heddle shaft was fastened to a cord, which passed over a pulley, and coming down by the side of the loons these cords were arranged in a board in the order in which the heddles required to be drawn. The (hawing of the cords and consequent formation of the shed was originally the work of a boy assistant, whence the namo draw-boy loons ; but it was found possible, by various mechanical attachments worked from the treadles, to dispense with extra aid to the weaver. But even with this arrangement the number of heddles which can be hung in any loom is limited, though, by using thin shafts and arranging them in tiers, as many as eighty or ninety may be accommodated. Since as many as a thousand separate sheds may lie required to form a complete pattern, a device other than shafts or leaves of heddles becomes necessary ; and the solution of the difficulty is found in hanging the individual heddle mails, not in shafts, but independently, each with a small lead weight called a lingo attached to it. Thus in effect a separate heddle is provided for each thread of warp, and it becomes possible to effect any combination of shed by cording together such leashes or mails as carry the warp threads to be raised. This tying together of the separate leashes, called "tying the harness" in the case of elaborate designs, is a tedious and difficult operation, requiring the exercise of considerable skill and patience. The successive sheds of a pattern being tied up, it is only necessary to have the cords arranged in the order in which they are to be drawn and attached to the mechanical device for pulling them, and forming the sheds in proper succession.

The Jacquard Loom. - The Jacquard apparatus is the most important and ingenious appliance which has ever been adapted to weaving, since by its agency it has become possible to produce the most intricate and extended patterns with the same certainty and with almost as much rapidity as plain cloth. The credit of introducing and making the machine a practical success - if not the whole honour of the invention - is due to Joseph Marie Jacquard of Lyons (see vol. xiii. p. 539). Attention was first directed to this ingenious artisan by a model of a net-making machine invented by him, which was deposited in the Conservatoire des Arts et Metiers. He was requested in 1801 by Napoleon to examine and improve on a com537 been acquainted with the fly shuttle which was then known and used at least in England, it is probable he would have come to be reand of the apparatus which bears Jacquard's name.

The fundamental principle of the Jacquard apparatus is simple, although in its working fine mechanical details are essential. Its object is to effect the raising of anynumber of separate leashes, corded leashes, or heddles, in any order and succession without special tying of harness. How the apparatus works will be made plain by the diagram, fig. 7. Here A, A represent the separate leashes through which the warp threads are drafted. It will be observed that these leashes are tied in pairs, but they might equally well be single, many together, or shafts of heddles. The cord from each separate leash passes through a finely perforated board B, called the comber-board, between which and C, the bottom board, the pairs are tied to a cord. These cords pass up through the bottom board, and are caught in the lower hooks of a range of double-hooked long wires D, D. These hooked wires are supported and kept in position by being passed through loops or eyes in a range of cross-wires E, E. The head of each cross-wire is formed into an oblong eye as at a (an enlarged representation of a single cross-wire), through which a pin is passed for securing it in the spring-box F, in which each separate cross-wire presses against a small helical spring. The oblong eye permits a certain amount of play in the cross-wire, so that it can be pressed back against the helical spring when a force is applied at the opposite end. The points of the cross-wires pass through a perforated board G, called the needle-board, projecting about a quarter of an inch beyond its outer surface. The upper hooks of the upright wires threaded through these cross-wires are attached to a board H, called the griffe. The whole function of the apparatus is to liberate these hooks in the order and to the extent necessary for the successive sheds. The hooks are dislocated thus. At the side of the projecting points of the cross-wires there is a quadrangular frame I, called the cylinder. This cylinder can be drawn back, and turned so that each face may in succession be presented to and pressed against the face from which the cross-wires protrude. The cylinder alone does not affect the wires, but its function is to carry on its rotating faces a succession of pasteboard cards which are punctured with holes in a definite order. The wires connected with hooks which are not to be disturbed pass through the punctured holes and remain unaffected, while those supporting the hooks to be displaced are pressed back by the cardboard surface, and this motion of the cross-wire lifts the hook of the upright wire off the griffe. The grille now rises, carrying with it the undisturbed hooks, making a shed of the warp threads attached to their cords. The weft is then shot, the griffe descends, and the next punctured card is by a quarter revolution of the cylinder brought into contact with the cross-wires, and so the work goes on, successive Jacquard cards being presented, new combinations of shed elected, and the weft shot till the pattern is completed. Hooks to any desired number may be arranged in a Jacquard apparatus, and when a separate hook is applied to each individual leash the most complete control and variety of shed may be secured. But in practice this is not necessary. Each repeat of a pattern across a web may be corded up to one series of hooks, and in many ways it is practicable to limit the number of books required in weaving and thus to simplify the apparatus itself, and the system of punctured cards by which its operation is governed. If the Jacquard apparatus, for example, is controlling only a few leaves of heddles, then only a corresponding number of hooks are called into use. Usually the machines are provided with 300, 400, 600, 900, and sometimes more hooks, and when intricate and extensive patterns are being woven two or more machines may be simultaneously brought to bear on the same loom.

The Power-Loons. - The first loom in which all the motions in weaving were connected and controlled by one of the sixteenth century (see RIBBONS, VOL xx. p. 531). In 1745 John Kay, inventor of the fly shuttle, and Joseph Steil patented improvements on the Dutch engine loom, which they said " may go or be worked by hands, water, or any other force." The ribbon loom may be regarded as a series of distinct looms mounted within one frame, each having its own warp and cloth beams, heddles, and shuttle, but all worked by one set of treadles and with a single batten. The shuttles are thrown across the narrow web by a rack-and-pinion arrangement ; they are simultaneously shot, and each occupies the place of its next neighbour to the right or left alternately. The Jacquard apparatus and the drop-box arrangement for changing shuttles with change of weft are applied to the ribbon loom.

The application of power to the weaving of ordinary webs has developed along a different line, and the common power-loom has nothing to do with the ribbon loom. So early as 1678 there was figured and described in the French Journal des Scarans a machine " for making linen cloth without the aid of a workman," the invention of Jacquard apparatus, embodied many improvements on the conception of De Gennes, and presented some of the important features of the modern power-loom. The practical realization of automatic weaving was, however, deferred for forty years, and the world owes it to a clergyman of the Church of England, the Rev. Dr Edmund Cartwright. His own graphic account of the history of his invention has already been given under COTTON (see vol. vi. p. 500). Dr Cartwright's original loom was but an imperfect machine, although his patent was minute and detailed. Both he and others devoted much labour to its improvement; and in bringing the invention to a successful issue he spent from £30,000 to £40,000, while in return he received only a gift of £10,000 in 1809 from the Government. The power-loom fought its way to supremacy but slowly, for an imperfect power-loom is no better than a hand-loom; and it was only after the minor adaptations and adjustments which frequently make the difference between success and failure were brought into operation that the real advantages of power-loom weaving became obvious. Even yet for many purposes the power-loom has not succeeded in supplanting hand-loom weaving.

The power-loom (fig. 8) differs much in appearance from the hand-loom, and is altogether more compact, from the fact that the lay, which is suspended from above in the latter, is in the power-loom centred below. The three principal motions, shedding, picking, and beating up, are of course the same in both. Motion is communicated to the working parts of the power-loom by the main 537 537 537 or crank shaft, so called because it is provided with the two cranks which give oscillating motion to the lay. By toothed wheels the crank shaft controls the motion of the tappet shaft which carries on it the cams or tappets (1) for the picking motion called the picking tappets, and (2) for the treadles called the shedding tappets. The picking tappets have always a direct relation to the motion of the crank shaft, because for every beat of the lay there must be a corresponding pick. As there are two picking tappets the shaft is therefore geared to make half a revolution for each revolution of the crank shaft. The relation of the shedding tappets is not so regular, their rotation being dependent on the number of heddles or sheds of wall) they control, and it is only in plain weaving that they correspond in motion with the picking tappets.

For the successful working of a power-loom several adjustments are necessary which are not required in the case of the hand-loom. The hand-loom weaver winds up his web on the cloth beam from time to time as the work progresses, and he moves forward the temples by which the woven fabric is kept extended to its proper breadth. In the power-loom these must be accomplished automatically, and the motions must be self-adjusting with the progress of weaving. More important still, a self-acting appliance must be provided to stop the motion of the loom in case of the weft thread becoming exhausted or being broken. This is secured by a delicate and ingenious contrivance called the "fork-and-grid stop motion," which depends for its action on the lightly balanced prongs of a fork. These prongs come, in contact with the weft thread between the selvedge of the web and the shuttle box each time the shuttle is shot to the side at which the apparatus is fixed. If the prongs meet no thread they arc not thrown up, and being unmoved a connexion is formed to the moving lay, and by a system of levers the loom is immediately thrown out of gear and stopped. Equally essential is it to provide means to stop the loom should the shuttle stick in the warp or otherwise fail to be carried from side to side of the lay. It is clear that, should the lay beat up with the shuttle sticking in the weft, there would ensue complete wreck of the warp. There are two ways of dealing with such a contingency. The first, invented in 1796 by Miller of Glasgow, is the "stop-rod motion," the action of which depends on the shuttle raising, as it enters the shuttle-box, a catch which if left down would strike against a frog or stop, and so throw the loom out of gear. The second device is the loose reed, in which there is an appliance for liberating the lower part of the reed when any obstruction is met in the warp, and thereby preventing a blow being given by the beating-up motion.

Double Cloth. - For many purposes the weaving of double cloth is important. It permits of the formation of a ground of inferior material with a surface of finer texture ; and it affords great scope for the formation of coloured patterns, allowing of the production of double-faced textures, which may or may not correspond in pattern according to pleasure. It moreover increases the thickness and weight of woven fabrics, and it is the basis of tubular weaving, such as is practised for making hose, tubes, seamless sacking, tic. There are three classes of double textures. The first consists of double warp surfaces with the weft in the centre ; in the second it is the reverse - a warp centre and two weft faces ; and in both these classes the two sides may be of different colours if two colours of warp and weft respectively are employed. In the third ease the cloth may consist of distinct warps and wefts throughout, and practically be two separate cloths. These, if bound at the selvedges, would become woven tubes, and if at regular intervals over the surface a thread of warp or weft passes from the one into the other they are united as one texture. The intersection of double warps and wefts gives the opportunity of producing great diversity of colour and pattern in any fabric without waste of material, and the manlier in which patterns may pass from side to side is illustrated in the sectional diagram, fig. 9. The diagram, fig. 10, illustrates lower. When a pick is being put in through the upper warp heddle 1 is up and all the others are down ; and when the shuttle is passed 537 at right angles by the weft. In gauze weaving, by which effects intermediate between lace and plain cloth are produced, the warp threads are made to intertwist more or less among themselves, thereby favouring the production of light open textures, in which many ornamental lace-like combinations can be effected. Plain gauze is a thin open texture, in which two contiguous threads of warp make each a half twist around the other at every pick, the cloth having in section the appearance shown in fig. 11. A len° con 537 twists with its neighbour only at every fourth piek. In fancy gauzes the crossing or whip warp may cross and entwine several ordinary warp threads at once, and in numerous other ways the simple principle of intertwisting may be used for ornamental effect. The mutual entwining of warp threads is accomplished by an extra heddle called a "doup," placed in front of the common heddles. The doup consists of a half heddle threaded through the eye of a plain heddle, of which it forms a part. The cross or whip warps arc drafted first through one of the ordinary heddles and then passed under the thread or threads they are intended to entwine, and drafted through the doup heddle, as seen in the diagram, fig. 12, which shows the drafting of a plain gauze. The whole of the warp yarns which are to be entwined must with the whip double cloth with the use of four the upper cloth, 3 and 4 the :hrough the lower web huddles L 2, 3 are raised and heddle 4 is lepressed.

Gauze Weaving. - Hitherto we warp be passed through a single split of the reed, except when the coups are placed in front of the reed, which is done in the case of complicated gauze weaving.

Pilcd fabrics are textures woven with a looped or otherwise raised surface. Looped pile is any fabric in which the woven loops remain uncut, as in Brussels and tapestry carpets and terry velvets. When these loops are cut in the finished texture then the material is a cut pile, such as ordinary velvet, fustian, imitation sealskin, and other imitation furs. For ordinary loop and cut pile fabrics two warps are required, the regular beam warp and the " pole " or pile warp. The latter, being raised into loops, is worked up more 537 rapidly than the ordinary warp, and it has consequently to be of greater length and wound on a separate beam. The ground or foundation may be either a plain or a twilled texture, and after every third pick of weft a wire is introduced into the shed and beaten up' and woven into the cloth. In this way, by the stretching of the pile warp over the wire, a row of loops is formed across the web, the size of the loops being regulated by the size of the wire. If a looped pile is being woven then it only remains to pull out the wires from behind and again weave them in in front as the work proceeds. But if cut pile is being made, then either the loops must be cut along the top before the wire is withdrawn, or the wire may at one end be provided with a knife edge which itself cuts the loops as it is being pulled out. For velvets, &c., the wires are provided with a groove on their upper face, and along this groove a cutting knife called a trivet is run to cut the loops. In fig. 13 the structure of a looped and cut velvet is illustrated. Fustian 537 substance of the pile. It is not woven over wires, and the pile is cut by hand after the web leaves the loom. A third method of weaving pile fabrics consists of making a double web, the pile 537 warp passing from the one to the other and binding them together, as shown in fig. 14. When the connecting threads are cut they form a pile surface for each separate cloth. The great difficulty which has been encountered in perfecting this method of pile weaving has been to keep the connecting pile equal in length throughout, and to cut it so as to produce uniform level surfaces. The success which has been attained in plush weaving with double cloth is largely due to the patient and well-directed efforts of Mr S. C. Lister, of Manningham Mills, Bradford.

There are many subsidiary but highly Important and most ingenious features of the art of weaving, specially in connexion with the production of ornamental surfaces, for notice of which it has been impossible to find room in the preceding summary. The extent and complexity of the whole subject renders tile presentation of a satisfactory outline of the art a matter of unusual difficulty; but those who wish to pursue the subject in detail, in addition to copious Information to be gleaned from technical journals, may consult Darlow's history and Principles of Wraring (London, 1878), Ashenhurst's Wearing and Designing of Textile Fabrics (Bradford, 1879), and Brown's Practical Treatise on the Art of Wearing (4th ed., Dundee, 1883). To the two works first named we have to acknowledge our indebtedness for the suggestions of several diagrams. (J. PA.)

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