Jacquard Weaving and Designing

by T. F. Bell

When several threads are put to the mail, it is also usual to put several picks to each card. The fewer picks, the finer will be the pattern; but a good method of regulating this is to make the checks formed on the cloth square, a little more or less according to the fineness of the pattern required. Thus, if the cloth is wefted square, or a little over that—say, 100 warp by 100 to 110 weft threads per inch—paint the design on, say, 8 × 8 or 8 × 9 paper, and give as many shots to the cards as there are threads in the mail. If the cloth is to be wefted one-half over square (100 × 150) the same pattern will still do, but with half as many more shots to the card than there are threads in the mail. If there are two threads in the mail there will be three picks to the card, but if there are three threads to the mail there must be four picks to one card and five to the next one. This would be for a pattern on 8 × 8, or square paper. If painted on 8 × 9 paper, which would give an extra card to every eight, and if the weft must not be increased, then four or five picks must be taken off the number given to the eight cards and put to the ninth one, for four cards with four picks to each and four with five picks to each = 36 picks, and thirty-six picks put to nine cards would allow four picks to each. This would make the edges of the pattern a little finer; and if the design was painted on 8 × 10 paper it would be finer still, as there would be more cards to a given number of picks.

In this way any alteration required can be made on the number of picks per inch given to cloth woven on a pressure or twilling harness, without distorting the pattern by varying the number of picks given to each card to suit the shotting. Neither is it necessary to have the same number of threads in each mail; the warp might be mailed 2’s and 3’s or 3’s and 4’s, but the more regular they are, the better. If the fineness of the cloth requires to be altered, it may be woven in the same harness without any alteration by varying the number of threads in the mails. For instance, a warp of ninety threads per inch mailed 3’s and one with 120 threads per inch mailed 4’s would work in the same harness. Similarly, the same set of cards would suit for making different widths of cloth by making the harness narrower in the cumber board and altering the mailing so as to keep the cloth the same set, or it may be made a finer set and not alter the mailing. In either case the pattern would be reduced in size.

[Fig. 111] shows a portion of a pressure-harness mounting which is similar to that of the draw loom. It is mounted in the same manner as described for full harness, only that the warp must be divided by the number of threads to be drawn into each mail in order to find the quantity of harness required. The kinds of mails used are shown at A and B, [Fig. 111]; it does not do to have more than two threads drawn into each eye of the mail, as they are liable to twist round each other; two will separate easily, but a greater number will not. Ordinary full-harness mails answer very well for a two-thread harness. The mails are levelled in the same position as for full-harness work, viz. about 1-1/2 in. below the level of the back and front beams for hand-loom work, and a little lower for power looms. The lingoes are heavier than those required for a full harness; the weight depends upon the strength of the yarn and the number of threads in the mail; 10 to 12 to 1 lb. are used in power looms for linen damask with two threads in the mail, having about eighty to one hundred threads of warp per inch. For hand looms they are usually made of lead, thicker and shorter than the wire lingoes, and called ‘leads’; 11 to 15 per lb. suits for three- or four-thread harnesses. Light cotton work, such as muslin curtains, only requires lingoes of about sixty or seventy to 1 lb. for hand looms, but from twenty-five to thirty per lb. are used in power looms for two-thread harnesses.

Fig. 111

The principle of working the pressure harness is best explained by the diaper mounting shown in [Fig. 2], where a back set of heddles takes the place of the harness, and a set of ground leaves of long-eyed heddles stands in front of the back ones. After the yarn is drawn into the harness or back mounting in the usual way, it must be drawn into the front or presser heddles, using, generally, a straight draught for a satin ground. If Figs. 2 and 111 are examined, it will be seen that when the shed is opened by the harness or back mounting, the heddles in front sink part of the raised warp and raise part of the sunk warp. The mounting raises all the warp of the figuring portion on each card or line of the design paper, and leaves down all the ground warp, so that it is necessary to have the heddles in front to bind the warp and weft, or form the texture of the cloth. For an 8-leaf satin eight shafts are required; one of these must be raised and another sunk for each shot, so as to raise the binding threads of the sunk warp and sink those of the raised warp, the harness forming the outline of the pattern, or raising the warp of it in a mass. The other six leaves of heddles stand in a middle position, and the long eyes allow the warp drawn by the harness to rise. When the machine is drawn it is held up till as many shots as are to be given to the card are thrown in, but the shed formed by the heddles must be changed for each shot. In working bars up the cloth one card would be sufficient, and when the machine is drawn it would be held so, and the cloth wrought with the heddles; of course, no machine would be required in this case, one leaf of heddles with the stripes of warp drawn into it would be sufficient for the back mounting. For dices two leaves of heddles would be sufficient for the back mounting, the warp of one dice to be drawn on one leaf, and that of the other on the other leaf; then one leaf would be raised and held up till one dice was wrought, when it would be lowered, and the other one raised and held up for the other dice. For fancy dices and diapers the plan of mounting in [Fig. 2] is very suitable and simple, but for a variety of figuring or flowering the jacquard is necessary.

It will be seen that the presser heddles have three positions, viz. a sunk, a raised, and a middle position. The length of the eyes is to allow the harness to open the shed when the heddles are stationary, or in their middle position. They must be a little longer than is required to open the shed at the back leaf of the heddles; for a 2-in. shed a 2-1/4-in. to 2-1/2-in. eye is used. When the heddles are stationary the lower loop of the eye should be fully 1/8 in. under the sunk warp, and there should be the same clearance at the top when the shed is drawn; some allow more. The shed for a pressure harness is usually very small in front of the reed, and requires a very small shuttle to be used, from 1/2 in. to 1 in. deep being the usual sizes. The depth of the shed that can be made depends principally on the elasticity of the yarn. With a linen warp a very small shed can be made, as the yarn has but little elasticity, and if overstrained will hang slack. For it the distance between the harness and the back shaft of the front mounting should be 10 in. to 12 in., and there should be a stretch of 27 in. to 34 in. behind the harness. The draw of the harness may then be 3 in. to 3-1/2 in., and the shed at the back shaft will be 1-3/4 in. to 2 in.; this will allow a shuttle of 3/4 in. to 7/8 in. deep to be used. For hand looms the shed is about 1-1/4 in. at the back shaft, and a shuttle of 1/2 in. deep is employed. The shed must be made very clear and regular, and the smaller it can be kept, the better. With a good cotton warp 7 in. is a sufficient distance to have between the harness and heddles, and will admit of a larger shed being formed; but it is not desirable to have too large a shed, as there is a considerable strain on the yarn, and a small, clear shed is more satisfactory. This would be assisted by bringing the harness as close as possible to the heddles.

One drawback to this method of working is the distance which separates the harness from the fell of the cloth, or even from the reed; and if there is any obstruction to the warp rising or falling, such as roughness in the heddles or reed, or lumps on the yarn, it will not, unless very tight, fall into its proper place, and the shuttle may pass over or under it when it should not do so, giving a picked or darned effect to the cloth; slack threads may cause the same.

The warp must be kept as tight as possible, and all the threads should be at a uniform tension, the heddles straining each thread alike; the harness should be as close to the heddles as the yarn will permit it to be. The space occupied by the harness, heddles, and traverse of lay should be no greater than is necessary; then, with a small but clear shed satisfactory work can be produced. When drawing a warp into the harness, a boy or girl sits behind, and hands the threads to the drawer-in, who takes them into the mails with a wire hook, and then either hands them to a second drawer-in sitting in front of the heddles, to be drawn into them, or passes them over and under a pair of rods tied across the harness so as to form a lease as she draws them in; and when she has all drawn into the harness, she begins to draw them into the heddles, a straight draught being mostly used for a twill or satin.