In any woven fabric we distinguish two systems of threads, the _Warp or
Chain_, running lengthways in the cloth, and the _Filling or Weft_,
crossing the former at right angles.
This crossing 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
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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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THE TAFFETA WEAVE
[Illustration: Fig. 16]
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[Illustration: Fig. 17]
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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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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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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" are evenly balanced, and _unevensided_ if either warp or
filling predominate on the face of the fabric; the latter class is
therefore subdivided in _Warp effects_ and _Filling effects_.
In the following a number of serge weaves are illustrated, the French
designations being added in some cases, as they are still extensively used
in the trade.
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