Theory of Silk Weaving | Page 3

or interlacing consists of every individual warp-thread being placed alternately under and over one or more threads of the filling system. The arrangement of this interlacing is technically called the _Weave_, and the variety in which the points of crossing can be distributed is practically endless.
It is principally the weave that lends to a fabric its character, influenced, of course, by the material used, the size and tension of the threads and the combination of the colors.
The weaves are divided into three main classes: the Foundation weaves. In the silk business they are known under the following names:
#The Taffeta Weave, The Serge Weave, The Satin Weave.#
In the foundation weaves each thread effects only one crossing in one repeat of the weave, and the points of interlacing occur in a given rotation. A repeat in the foundation weaves comprises the same number of warp-threads as of picks or filling threads, and if this number is 8, for [Page 16] instance, the weave is called an 8-shaft or an 8-harness weave. In marking out a weave, the warp-threads are represented by vertical lines, the filling by horizontal ones, or in each case by the space between these lines. The places where a warp-thread lies over the filling are marked with paint or simply with a cross. In a similar manner we mark out the _chain draft_, which indicates the rotation in which the shafts are raised.
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[Page 17] THE TAFFETA WEAVE
[Illustration: Fig. 16]
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[Illustration: Fig. 17]
[Page 18] This is the simplest and oldest method of interlacing. The odd numbers of warp-threads cross the even numbers after every pick; hence of two warp-threads one will always go over the first pick and under the second, and the other end under the first and over the second pick. Taffeta cloth, therefore, has the same appearance on both sides, and in cotton and wool weaving this weave is technically--and properly indeed--called the Plain Weave. It has the smallest repeat, 2 warp-threads and 2 picks, and the exchanging of warp and filling is the most frequent possible. The cloth thus produced is firmer and stronger than that obtained with any other weave.
Fig. 16 is a taffeta on 4 shafts straight draw, the draft executed in the manner which we have already mentioned in explaining the drawing-in drafts.
Fig. 17 on common designing paper, illustrates a taffeta made on 8-harness, skip draw.
Be it mentioned that the drawing-in draft and the chain draft will be added throughout this work, the former over the weave to correspond with the respective warp-threads, the latter to the right of the drawing-in draft.
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[Page 19] GROS DE TOURS WEAVES
[Illustration: Fig. 18]
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[Illustration: Fig. 19]
In this weave the working of the warp is the same as in taffeta, except that instead of one pick, two or more are inserted in the same shed. It is mostly used in selvedges, where it serves to give more firmness to the edge of an otherwise loosely woven cloth, and prevents the weaving ahead of the edge in a tight weave. Gros de Tours is sometimes used, especially when cotton or wool filling is employed, with a view to lay two picks nicely side by side, whereas a thread entered two ply with the taffeta weave will always receive some twist, which may disturb the perfect evenness of the fabric.
Fig. 18 is a Gros de Tours with two picks on four harness straight through.
Fig. 19 illustrates this weave with three picks drawn end and end on two sections of four shafts each.
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[Page 20] SERGE or TWILL WEAVES
While the taffeta weave produces either an entirely smooth fabric, or one with a distinct transverse rib as in gros-grain, the twill weave forms diagonal lines on the cloth, running either from left to right or from right to left.
To make a twill, not less than three ends and three picks are required, of which each thread floats over two of the other system and interlaces with the third. The rotation of the interlacing is always consecutive, that is it moves with each succeeding pick one thread to the right (or to the left if the lines are to run in that direction). If warp and filling have the same texture, that is the same number of threads in a given space, the twill lines will form an angle of 45°; if the warp stands closer than the filling, the incline will be steeper, and in the opposite case the angle will approach more the horizontal.
The weaves can be expressed in numbers, for instance: the 3-end twill warp effect would be marked 2-1, which indicates that each warp-thread goes over two and under one pick.
Twill weaves are called evensided when the arrangement of "warp up" and "filling up"