_Combination of Weaves in a Fine Web—Sunken Effects Made on Head Motion
and Jacquard Looms—Employment of More Than One Bank of Shuttles—The
Overshot Method—Use of Different Colors and Grades of Stock—Binding Long
Floats_
A very effective combination of weaves in a fine web is seen at Fig. 1.
The middle of this web has for the face a 7 up and 1 down weave, but the
yarn and picking are fine. The yarn piles up just enough next to the
plain edge weave to set off the weaves in contrast to each other. It will
be noted that on either side of the silk figure there are two cords with
the binder thread left out between each, which further sharpens up the
contrast. The fancy effect is produced by the use of a heavy cabled cord,
the two outside threads being of reverse twist, so that when they pearl
up on contraction of the web, one turns to the right and the other turns
to the left, making an effective border.
SUNKEN EFFECTS
An altogether different type of figuring is seen in Figs. 2 and 3. Both
of these webs illustrate what is known as the sunken effect. In both
cases the face is a three-leaf twill, which character of weave is most
effective in hiding the filling beneath it. Therefore, the figure may
be worked out in sharp contrast. In Fig. 2, which is made on a fancy
head loom, it will be noticed that the face threads on the fifth cord on
either side are left out in order to assist in the carrying out of the
plaid effect aimed at in the figure. It will also be seen that the face
warp is striped in color. The character of the figure is such that the
major part of the face warp is operated in one solid block, making it
practicable to produce this on harnesses worked on a chain loom.
In the web illustrated at Fig. 3, each thread is operated in the design
independently. Such designs are only producible on a jacquard loom. But
inasmuch as the threads used in forming the figure are confined to the
face warp, it is not necessary to operate the back or binder threads from
the jacquard. It is more convenient to have these worked from the cams or
fancy head in combination with the jacquard, for the reason that a truer
and clearer shed can be obtained.
Furthermore, by having the back harness and the jacquard operated from
two distinct movements it becomes possible to time them differently so
as to obtain better results in the clearance of the stock in the shed. A
208 hook machine affords ample capacity for the making of these goods,
allowing for 26 rows of 8 hooks each, which will cover the requirements
of nearly all classes of web, giving an entire row to each cord. Such
arrangements will allow for six hooks for the face, one for the binder
and one for the gut on each row. Thus it will be practicable to use
different colored threads for the gut, which may be brought up in the
design in relief effects to the main figure as required.
CALCULATION FOR FIGURE DISTRIBUTION
In this type of figuring, calculation must be made to distribute the
figure uniformly so as to get a well balanced flat effect of the web.
As already stated, wherever the filling is shown, all the face stock at
these points is buried between the upper and the lower cloths, and is
acting as filler or gut in these places, preventing contraction. Should
heavy blocks be thus designed, the web would pucker up in an unseemly
manner. The filling used should be soft and uniformly spun, so that it
will mass well together and in a great measure prevent the buried face
stock from pricking through.
In designing webs of this character, calculations have to be made from
the web after it is woven and finished, otherwise the design may be
out of the desired proportion. A web may have 60 picks per inch on the
breast plate while weaving, but when contraction has taken place after
going through the press, it may have shrunk as much as 50 per cent.
The steaming and finishing process may further contract it another 10
per cent. which might make the picks about 100 per inch. Of these only
one-half appear on the face and the other half on the back. Therefore 50
picks per inch will be the proportion in which the design should be made,
and paper scaled according must be used.
CROSS SHOT WEAVING
We have so far confined our remarks to webs made on single shuttle looms.
Turning our attention to the use of more than one bank of shuttles we
would first make note of what is known as the cross shot. This is a form
of weaving which largely increases the output and has in it the further
element of economy, inasmuch as by this method the rubber warp can be
worked at a much higher tension than by the single shuttle method.
In the construction of single shuttle webs, the rubber harness rises
and falls at each passage of the shuttle across the shed. This movement
creates a friction on the rubber thread at the harness eye and an added
friction at the front reed by its passing up and down in the dent.
Friction is still further increased by the backward and forward movement
of the lay, which makes two such passages to one made by the cross shot.
In the cross shot method, the rubber remains stationary, with no upward
and downward motion, which enables the rubber thread to be stretched out
to its extreme limit while weaving, with little danger of chafing or
breaking. Over and under this stationary rubber are two distinct sheds,
one making the upper and the other the lower cloth. These two fabrics are
stitched together by the binder warp, which travels up and down through
both of these sheds.
In order to keep all the warp threads uniformly tight while shedding, it
is necessary to run these under separate back rolls, fixed at different
heights, properly centering the upper and lower sheds with the harness
and breast beams.
POSITION OF ROLLS
Fig. 4 will explain the position of the various rolls in relation to the
breast beam. It will also show the peculiar formation of the shuttles
used for this type of weaving, both pointing to one common center, made
necessary by the character of the two sheds. The bow of the upper shuttle
must be tipped downwards, and the lower bank must be tipped upwards, so
as to reduce the friction of the shuttles all possible when they are
passing through the sheds.
The round edge or covering for the outside rubber threads is drawn in the
harness on the upper shed, and while being woven this cloth is pulled
around the rubbers by the tension of the filling which is carried in the
lower shuttle. This tension is greater than that carried in the upper
shuttle, and so asserts itself by pulling the edge cloth around the
outside rubber until it meets the back cloth weave. The upper and lower
fillings are connected by what are known as tie threads. These threads
are drawn in the harness at each side of the body warp, next to the
edge, and are part of the binder warp. They are operated from the binder
harness, but are only allowed to travel through the lower shed as far as
the center of the web, instead of going all through both sheds, as do
the balance of the binder warp. This movement is accomplished by the use
of long looped harness eyes, which only carry these particular threads
through the one shed.
[Illustration: Fig. 1.—Effective Combination of Weaves In a Fine Web]
[Illustration: Figs. 2 and 3.—Sunken Effects]
[Illustration: Fig. 1A.—Harness and Chain Draft for Fig. 1]
[Illustration: Fig. 4.—Position of Rolls in Relation to Breast Beam for
Cross Shot Weaving]
The binder movement, extending through the two sheds, is formed by a
longer sweep from extra throw cams, or by the use of extended cam jacks,
or by a combination of both. The balance of these goods may be regulated
both by the warp and the filling, and any tendency towards curling may be
corrected by changing the weight of stock used on either.
USE OF DIFFERENT STOCKS AND COLORS
The use of upper and lower fillings also allows for the use of different
grades of stock in either shuttle. Colors may be used to match the face
warps while white may be carried in the lower shuttle to match the back.
Silk or other expensive stock may be used for the face without changing
the character of the stock used for the back of the goods, which is not
practicable in single shuttle work.
All this of course makes it possible to reduce the cost, making this
the most economical web produced. In the making of shoe goring, a
considerable quantity of which is still used for inserts for house
slippers, this is a very popular form of weaving, allowing for the
production of a face having a velvet-like pile of the color to match the
shoe leather, while the back may be perfectly plain and white.
It is a method employed in combination with the jacquard, where fancy
figures may be obtained on the face, using the cam movement for the back,
binder and edge, the weave of which is the same for all of these warps,
being simply a one up and one down. In such a combination the labor on
the jacquard movement is much reduced, inasmuch as the travel of the
lingo is much shorter than is required when made in connection with
single shuttle.
THE OVERSHOT METHOD
The overshot method, which we have previously referred to, is another
form of double shuttle web which has in it elements of economy differing
from the cross shot but equally important. This kind of weaving is
designed as a substitute for silk jacquard webs, which it has to a great
extent supplemented. Before its introduction it was customary to use a
slow running “rise and fall” lay movement, when making a silk figure with
the shuttle, putting in one pick of silk filling to each two body picks,
so that the output of web was only about one-half of what is possible
in overshot weaving. In the old method the silk used to pass from edge
to edge of the goods at each pick of the figure shuttle, and where the
figure did not appear it was buried between the upper and the lower
cloths.
In the overshot method the silk figure is bound down at the edge or
border of the figure and none of the silk is entirely buried out of
sight. In the overshot the body shuttle runs all the time, while the
figure or silk shuttle only runs with every alternate pick. The main
body of the goods is woven in every respect the same as in a single
shuttle web, and it may embrace all the weaves, such as plains, twills
or fancies, which are common to single shuttle weaving. Arrangements are
made, however, for the production of an auxiliary shed, by a movement
which pulls certain threads above the main shed, and while these are
open to pass the extra shuttle under them, and thus bind in the figure
filling. The lower part of the lay has straight shuttles, while the
upper bank of shuttles is tipped down to conform to the formation of the
auxiliary shed they are designed to pass through.
The binder threads from which the overshot figure is generally operated,
are weighted very lightly so that the individual threads will easily
stand the strain they will be subject to while making the auxiliary
shed. The Crompton & Knowles overshot dobby is generally used for this
purpose. This special machine is provided with two horizontal draw
knives, operating any or all of the 30 hooks, and is so arranged that
the connected warp threads may be lifted at either or both picks to the
height of the main shed, or to the additional height of the auxiliary
shed.
[Illustration: Fig. 5.—Simple Overshot Design]
[Illustration: Fig. 5A.—Draft for Fig. 5]
In Fig. 5A is seen the draft of a simple overshot figure covering 23
hooks, which are operated from one knife drawing in unison with the
binder harness, while the other knife is operating on the alternate shed,
or the heavy pick, and working in unison with the rubber harness. It will
be noticed that in the overshot design both sides of the figure do not
operate alike, but follow one pick behind the other. This is so arranged
that the binder may come up at the right pick to properly bind down the
silk in the goods, and so avoid any irregularity or ragged appearance at
the border of the figure.
MAKING OVERSHOT DESIGNS
In making overshot designs, care must be taken not to have the silk float
too long, or it will give the goods a rough coarse appearance. Should the
design call for a long span over a number of cords, it will be necessary
to bind at intervals as shown in Fig. 5A, and at each succeeding pick to
break the order of the binding as may seem advisable. The stitch or warp
figure coming up at each side of the main figure, must be pegged on the
dobby chain to operate on the reverse knife to the overshot figure, so as
to work on the pick when the binder harness is down.
[Illustration: Figs. 6 and 7.—Other Forms of Overshot Design]
Fig. 6 is an example of another form of overshot design, known as the
“matelasse.” In this the silk filling extends from side to side of the
web, as in the old form of jacquard, being bound down at different
points, the bindings forming the figure.
Fig. 7 shows still another form of overshot made by the operation of the
gut as figure instead of the binder, and which is worked on the heavy
pick instead of on the binder pick. This is done so that the intersecting
cords of face, which hide the silk at different points, can be raised in
order that the figure silk be hidden underneath it. To accomplish this,
each of these face threads is passed through slip leashes, which are
operated from the dobby. These slip leashes allow for the working of the
face thread in the main harness. At the same time it is possible to raise
them to the height of the upper shed so that the silk shuttle may pass
under them.