Fabric Structure and Designing

Where warps do assist to form figure it rarely happens that more than three can be used without overcrowding the reed. Fig. 17 gives the design, and a transverse section of a reversible tapestry in four colours, two of which are warps and two wefts. If either warp or weft is on the surface, corresponding threads are beneath. The bent lines represent weft and the circles warp. In this design the marks indicate the colours showing on the surface of the cloth, and not the lifting of the warp. Thus, crosses show No. I warp on the surface, filled squares show No. 2 warp, dots show No. i weft and oblique marks No. 2 weft on the face of the fabric. Each verti cal line of squares represents one thread of each warp and each horizontal line rep resents one thread of each weft. Figured repps differ from plain ones in having threads of one, or more than one, thick warp floated over thick and thin weft alike; or in having several differently col oured warps from which a fixed number of threads are lifted over each thick weft thread; the figure is due to colour.

Group 3. Piled Fabrics.

In all methods of weaving hitherto dealt with the warp and weft threads have been laid in longitu dinal and transverse parallel lines. In piled fabrics, however, portions of the weft or warp assume a position at right angles to the surface of the cloth. If the former there are two series of weft threads, one being inter sected with the warp to form a firm ground texture, the other be ing bound into the ground at regular intervals, as in the design and transverse section of a velveteen, fig. 18; the circles and waved lines form plain cloth, and the loose thread A is a pile pick. After leaving the loom all threads A are cut by pushing a knife lengthwise between the plain cloth and the pile. As each pick is severed both pieces rise verti cally and the fibres open out as at B. Since the pile threads are from two to six times as numerous as those of the ground, and rise from an immense number of places, a uniform brush-like surface is formed. Raised figures are produced by carrying the threads A beneath the ground cloth, where no figure is required, so that the knife shall only cut those portions of the pile weft that remain on the surface. The effect upon the face varies with the distribution of the binding points, and the length of pile is determined by the distance separating one point from another. When chenille is used in the construction of fig ured weft-pile fabrics, it is neces sary to employ two weaving op erations, namely, one to furnish the chenille, the other to place it in the final fabric. Chenille is made from groups of warp threads that are separated from each other by considerable inter vals; then, multi-coloured wefts are passed from side to side in ac cordance with a predetermined scheme. This fabric is next cut midway between the groups of warp into longitudinal strips, and, if reversible fabrics such as table-covers and curtains are required, each strip is twisted axially until the protruding ends of weft radiate from the core of warp, and form a cylinder of pile. In the second weaving this chenille is folded backward and forward in a second warp to lay the col ours in their appointed places and pile projects on both sides of the fabric. If chenille is intended for carpets, the ends of pile weft are bent in one direction and then woven into the upper surface of a strong ground texture. Warp

piled fabrics have at least two series of warp threads to one of weft, and are more varied in structure than weft-piled fabrics, because they may be either plain or figured, and have their sur faces cut, looped or both. Velvets and plushes are woven single and double. In the former case both ground and pile warps are intersected with the weft, but at intervals of two or three picks the pile threads are lifted over a wire, which is subsequently with drawn; if the wire is furnished with a knife at its outer extrem ity, in withdrawing it the pile threads are cut, but if the wire is pointed a line of loops remains, as in terry velvet. Fig. 19 is the design and two longitudinal sections of a Utrecht velvet. The circles are weft threads, and the bent line is a pile thread, part of which is shown cut, another part being looped over a wire. The circles are repeated to show how the groundwarp intersects the weft. In the design the filled squares show the pile warp lifted over the wires.

Double plushes consist of two distinct ground textures which are kept far enough apart to ensure the requisite length of As weaving proceeds the pile threads are interlaced with each series of weft threads, and passed from one to the other. The uniting pile material is next severed mid way between the upper and lower textures, and two equal fabrics result. Fig. 20 gives three longitudinal sections of a double pile fabric. The circles A, B are weft threads in the upper and lower fabrics respectively; the lines that interlace with these wefts are pile warp threads which pass vertically from one fabric to the other. At C, D the circles are repeated to show how the ground warps intersect the wefts, and at E the arrows indi cate the cutting point. Figured warp-pile fabrics are made with regular and irregular cut and looped surfaces. If regular, the effect is due to colour, and this again may be accomplished in various ways, such as (a) by knotting tufts of coloured threads upon a warp, as in Eastern carpets; (b) by printing a fabric after it leaves the loom; (c) by printing each pile thread before plac ing it in a loom, so that a pattern shall be formed simultaneously with a pile surface, as in tapestry carpets; (d) by providing several sets of pile threads, no two of which are similar in colour; then, if five sets are available, one-fifth of all the pile warp must be lifted over each wire, but any one of five colours may be selected at any place, as in Brussels and Wilton carpets. Fig. 21 is a longitudinal section of a Brussels carpet. The circles represent two tiers of weft, and the lines of pile threads, when not lifted over a wire to form loops, are laid between the wefts ; the ground warp interlaces with the weft to bind the whole together. When the surface of a piled fabric is irregular, also when cut and looped pile are used in combination, de sign is no longer dependent upon colour, for in the former case pile threads are only lifted over wires where required, at other places a flat texture is formed. In the latter case the entire sur face of a fabric is covered with pile, but if the figure is cut and the ground looped the pattern will be distinct.