_LENO WEAVING_
The word “leno” has latterly become a general term given to all classes
of cross weaving. Originally it had a different meaning to gauze, but
the word is now often applied to gauze as well as other fabrics woven
with doups. A pure gauze fabric is one in which the crossing thread
is brought up on one side of a standard end, and up the other side of
the standard end on the next pick. Fig. 135 shows how the threads are
interlaced in gauze weaving. It will be seen that the weave repeats
every two picks. The crossing end, and the end round which it crosses,
must be placed in one dent, and if an end is made to cross round a
number of ends they must all be in the same dent or split in the reed,
as it is very obvious that an end cannot be made to cross into another
dent with the ordinary doup heald.
[Illustration: FIG. 135.]
[Illustration: FIG. 136.]
[Illustration: FIG. 137.]
The end is made to cross from one side to the other by means of a doup
heald. These healds consist of an ordinary heald with an extra half,
generally called a “loose half” or slip. The method of knitting the
doup heald will be understood from Fig. 136. It is obvious that when
the doup is lifted at A, the end contained in the doup will be lifted
up on the right-hand side of the end E. In order to bring the same end
up on the left-hand side of E, the ends are drawn through the healds,
as shown at Fig. 137. There are two ordinary staves, and the ends are
drawn through them as for plain cloth with two staves. Then the end
which is drawn through the first stave is crossed under the end which
is drawn through the second stave, and is then drawn through the doup
in the manner shown at Fig. 136. When the doup is lifted it will lift
the crossing end A up on the right-hand side of the standard end B;
but in order to do this easily the end must be slackened. This is done
by taking all the crossing ends A from the warp beam over a slackening
rod or vibrator, R; the other ends of the warp B are taken over the
back rest in the ordinary manner. The slackener is usually in the form
of a lever, one end of which can be lifted by the dobby or whatever
shedding motion is used, and when the dobby lifts one end of the lever
the rod is moved downward, thus slackening the warp which is drawn
over the rod. Whenever the doup is lifted the crossing warp must be
slackened, or it would cause the standard end B to be lifted, as it is
crossed under it. In this manner when the doup is lifted the doup end
is brought up on the right of the end B. In order to bring the same
end up on the left of B, it is necessary to lift the first stave and
the loose half of the doup. The first stave naturally takes the end up
on the left-hand side of B, but it is necessary to lift the loose half
in order to let the end go up on that side. It is usual to show the
doup by a double line in the draft, the front line always representing
the loose half. The pegging plan or lifting plan for the healds is for
leno fabrics not usually shown on point paper, although it may be, just
as easily as any other way. The usual way is to rule horizontal lines
representing the staves and perpendicular lines representing the picks,
and to put a ~/~ on the shafts to be lifted for each pick. It is
easy to do this by continuing the lines which represent the shaft in
the draft, and to make the pegging plan on the same lines by the side
of the draft, as in Fig. 137. The two perpendicular lines one and two
represent the picks, and the marks on the first pick are on the loose
half, the doup, and the slackener; therefore all these will have to be
lifted. (It is usual to peg the dobby to lift the loose half along with
the doup to take the strain off the healds.) On the second pick the
marks are on the loose half and the first stave, therefore these must
be lifted for the second pick.
With the same draft as in Fig. 137, a considerable variety of patterns
can be made of a style known as crossover lenos. This style consists in
weaving a number of picks plain, and then making a cross with the end.
At Fig. 138 the design draft and pegging plan are given for a “five
and one” crossover leno. From the design it will be seen that the doup
is required to be lifted for the first pick, and the first stave and
loose half for the second pick, the second stave for the third pick,
and so on. This lifting is shown in the pegging plan at the right of
the draft, where on the first pick marks are put on the doup and loose
half the slackener, and on the second pick on the loose half and first
stave, and so on. There are in this pattern six picks to the round. The
appearance of the cloth will be a bar of five picks plain, and then a
crank or open space, in the middle of which is a single pick; the crack
is caused by the crossing of the ends.
[Illustration: FIG. 138.]
In gauzes and fabrics of this description, a thin open fabric in which
the ends will not fray or slide is the object. The nature of the weave
enables a firmer fabric to be obtained with a smaller number of ends
and picks per inch than in ordinary weaving where the threads are not
crossed.
[Illustration: FIG. 139.]
[Illustration: FIG. 140.]
Another and quite distinct effect is produced with doups. This is
commonly called “lace” or net, and is often combined with gauze or
other “open” leno effect in stripes known as “lace and leno stripes.”
This lace effect is produced by making a thick end form a zigzag on the
plain ground. The interlacing of the threads in a simple lace or net
stripe is shown at Fig. 139. A thick end, A, is brought up first on
one side and then on the other side of two plain or nearly plain ends,
B and C. There are ten picks to the round, and by the side of this
dent there is another thick end twisting in the opposite direction,
first up one side, and then up the other of two more plain or nearly
plain ends. Each thick end comes up for two picks at one side and then
crosses under and comes up on the other side after an interval of three
picks, and _vice versâ_. The marks represent the ends lifted. By the
side of the lace there are two plain ends shown, which represent the
unlimited number of ends used for the ground of the fabric. In weaving
this pattern the draft and pegging given at Fig. 140 would be used.
By carefully following the design with the draft and pegging plan the
principle will be easily mastered. The arrangement of the shafts is
rather important. The doup is placed in front, the ground staves next,
and the leno or net staves next. It is immaterial whether the crossing
ends be taken through the first stave of the three used for the leno,
or the back one--some prefer one way, some another--but it is necessary
to get the leno staves as far back as possible to give the thread a
better chance of crossing. Four staves are taken for the plain, as
in ordinary weaving, to prevent overcrowding. The lifting marks on
the pegging plan will be easily followed if the one in Fig. 138 was
understood. Where the fifth stave is lifted the loose half is lifted
also, and both thick threads come up on the inside. Where the doup is
lifted the slackener is lifted also, and the ends are brought up on the
outside as on the sixth and seventh picks. More will be said on the
arrangement of shafts in the chapter dealing with designs for leno. The
explanations on the structure of the fabrics at this point are only for
the purpose of enabling the requirements of the looms for weaving them
to be understood. Some manufacturers prefer to work with the doups at
the top of the loom, especially in weaving net lenos. In this case the
crossing end is crossed over the others and slipped downwards.
It used to be considered that gauze and lenos could not be woven
on double-lift machines. In other places than Lancashire this idea
prevails to-day to a great extent, but of course this is a great
mistake. The simpler kinds of lenos, such as pure gauze and crossovers,
are sometimes woven on tappets, which are, of course, double-lift.
The tappets are of the ordinary kind, drawn on the same principle as
described earlier in this book; but the tappet which operates the
standard ends is made to lift the staves halfway when the doup end
is crossing. Tappets of this kind have been used for some time past,
and it is not surprising that the same principle should be applied
to double-lift dobbies. Instead of drawing the tappets to lift the
standard ends half way or a little way to enable the ends to cross
easier, the easing motion usually employed for dobbies is often used,
and the tappets are of the ordinary kind.
In a double-lift dobby the healds begin to lift for one pick when the
healds which are up for the previous pick begin to come down. In the
case of Fig. 137, when the doup is lifted for the first pick and begins
to come down, the same end is being taken up the other side of B by the
stave No. 1 being lifted. If the end B were not moved it would very
soon be broken by the crossing end being made to act in this saw-like
manner upon it. It is necessary, therefore, to lift the end B about
halfway up at the moment the crossing end begins to come down and to
pass to the other side of B. If the end A has not to cross for the
next pick, it would not be necessary to lift the end B at all. In a
single-lift machine the doup will get to the bottom before the first
stave begins to rise, and therefore there would be no difficulty in the
end crossing. In a double-lift dobby the staves containing the ends
round which the doup thread crosses are lifted partly up every pick by
a lever worked from the crank arm of the loom. This easing motion or
“shaker” is shown at Fig. 141. AB is the crank-arm, and the upright
CD is connected to the crank-arm at C, and to a lever ED at D. EG is
another lever on the rod E, and the healds which are to be lifted half
way are connected to this lever at G, as well as to the jacks in the
dobby. As the crank revolves the oscillation of the crank arm imparts a
similar movement to the lever ED, and to the staves which are connected
to EG. This motion commences just at the proper time. Of course, when
the crank-arm is lifting the healds, the cords connecting these healds
to the dobby will be slack, as indicated at Fig. 141. By thus lifting
the standard healds, the crossing is greatly facilitated.
[Illustration: FIG. 141.]
This easing motion is not required where there is no crossing of the
end immediately, as, for instance, in Fig. 139, the doup end after
being brought up on one side is never required up on the other side
on the pick immediately succeeding, therefore the end has time to get
down before being lifted on the other side and an easing motion is not
required.
[Illustration: FIG. 142.]
The method of slackening the warp when the doup lifts is shown at Fig.
142. This diagram shows a two-doup arrangement. For gauze and similar
weaves it is not necessary to have a separate beam for the crossing
warp, as one end pulls the other and the take-up is about the same; but
for net lenos or laces after the manner of the fabric in Fig. 139 it is
necessary to have the crossing ends on a separate beam, as a great deal
more in length of this warp is required than for the plain. Sometimes
several beams are used, the only limit being the number which can be
placed in a given space.
At Fig. 142 the crossing warp from the bottom beam is taken over the
slackening rod A, and over the carrier E. The crossing warp from the
top beam is taken under the slackening rod B. A moves about a centre D,
and B moves about a centre C.
The slackener B is connected to a jack in the dobby by the cord L, and
the slackener A is connected to another jack by the cord M. When either
L or M is lifted, the warp over its rod will be slackened.
FULL CROSS LENO.
[Illustration: FIG. 143.]
A full cross may be made by taking the doup completely round the
standard end, as in Fig. 143, and alternately lifting the doup and the
other end. This is a much more difficult weave than ordinary leno, and
is not much used, although it gives a very pleasing effect when woven
with thick yarns. The weave repeats on two picks as in gauze, but it
is necessary to use very strong twist in order to bear the strain and
friction unavoidable in this crossing.
THE LENO JACQUARD.
[Illustration: FIG. 144.]
Where figures are required to be thrown up on a leno ground a Jacquard
mounting is required. It is possible to weave a plain figure on a gauze
ground with an ordinary Jacquard harness and an ordinary doup stave
in front, but this can only be done on a pure gauze ground--that is,
one end crossing one. A plain figure on a ground of this kind does not
afford a sufficiently powerful contrast to the ground. It is necessary
in order to produce a really efficient contrast to have two ends
crossing two and weaving separately in the plain. A fabric of this kind
is one of the most beautiful of all fabrics, and is remarkably cheap
and serviceable in wear. The method of producing a plain figure on a
gauze ground with one doup in front of any ordinary Jacquard harness
is illustrated at Fig. 144. The ends are drawn through the Jacquard as
usual, and are then taken in pairs and one crossed under the other, the
crossing end being taken through the doup, as shown in the diagram. The
crossing end in each pair is marked A. We can now see how either plain
or gauze can be woven at will. The doup is lifted for the first pick,
and this brings all the ends A up at the right hand side of ends B (see
first pick). In the first two dents the ends A are lifted again by the
harness, and the loose half of the doup being lifted will enable the
ends A to cross to the left side of the ends B. The doup is lifted for
the third pick, and it is obvious that this will weave gauze with the
first two dents. After the doup is lifted, if the end B is lifted on
the next pick, it will cause plain to be woven, as will be seen from
the diagram, where the third and fourth dents are weaving plain when
the first and second dents are weaving gauze, and _vice versâ_.
[Illustration: FIG. 145.]
[Illustration: FIG. 146.]
A proper leno harness is illustrated at Fig. 145. It is obviously
impossible with the arrangement given at Fig. 144 to weave a leno
with two ends crossing two in conjunction with plain, as there would
require to be two ends in each eye in the doup, and as the doup is
lifted every other pick, it is impossible to change to plain from the
leno. To obtain a figured leno of this description, each dent must have
a doup to itself, and the doups must be lifted by the hooks. At Fig.
145 the arrangement of the harness is shown. The machine is a single
lift, and in order to obtain a 400 end figure 600 hooks are required.
These are arranged in twelve rows, the two front rows being used for
the doup harness, the two back rows for the slackening harness, and the
eight middle rows for the ground or figure harness. For the 600 hooks
only 500 needles are used, the doup hook and its slackening hook being
connected with the same needle. The top and bottom needles are used for
the doups and slackeners, as shown in the diagram, and the eight middle
rows of needles for the ground or figure harness. The method of drawing
the warp through the harness is shown at Fig. 146. The two crossing
ends are drawn through the slackening harness, and all the ends are
drawn through the ground harness. It is immaterial whether the draft is
from back to front or front to back; some manufacturers of these goods
draw the ends from front to back. Of course, this must be borne in
mind in designing and cutting the cards. After being drawn through the
ground harness the two crossing ends are crossed under the other two
and drawn through a doup. The mails in the doup lingoes are specially
made to allow the thread from the slip to pass through and back again.
The shaft A (Fig. 145) is the slip or loose half, and serves for all
the doups. The mails in the slackening harness are placed, lower down
than the other warp, and these mails hang between two rods, B and C,
which are called the “bridge.” Sometimes only one rod is used, and this
serves equally well.
A better shed is formed by only lifting the slackening hooks half as
much as the other hooks, and therefore a special device is required for
giving only half the lift to these hooks. In the illustration, Fig.
145, there are two griffes, E and H, and the griffe E is connected to
the lever GK at a point, O, about midway between the fulcrum G and
the point where the griffe H is connected to the lever. The fulcrum G
is movable in a slot made for that purpose, so that the lift of E can
be altered a little if desired. When the griffe H is lifted in the
ordinary manner, it is obvious that the griffe E will only be lifted
about half way.
[Illustration: FIG. 147.]
The usual method of obtaining the half-lift, which this invention is
intended to supplant, is illustrated at Fig. 147. This method was
invented by the late Mr. Tootal Broadhurst, and has been in regular use
a long time. Each of the slackening hooks lifts a lever CP, centred at
C, the slackening harness is tied to these levers about midway between
C and P, and thus the mails are lifted only about half as much as the
hooks. Of course, in this case all the hooks in the machine are lifted
by one griffe, and therefore the slackening hooks are lifted as far as
the others.
This method serves its purpose very well, but if any alteration is
required in the lift of the slackening harness all the levers have to
be gone through and altered separately, whereas in the Devoge machine
the lift can be regulated to a nicety by moving the fulcrum G and the
point O. The slackening harness should be placed from nine inches to a
foot behind the ground harness.
The wire M, in Fig. 145, is for lifting the shaft A, which is required
to be lifted every pick. The advantage of using only one needle for the
doup and slackening hooks is that it prevents the possibility of the
slackener being missed when the doup lifts, as well as being a saving
in cards.
By lifting the crossing ends with the ground harness for two or more
picks, followed by lifting the same ends in the doup harness for a
similar number of picks, an open leno fabric is produced, and a plain
figure can be woven by lifting the ground harness plain, or a floated
figure can be formed exactly as with an ordinary Jacquard.
[Illustration: FIG. 148.]
[Illustration: FIG. 149.]
The usual method of putting the design on point paper for these
Jacquards is illustrated at Fig. 148. In the plan eight ends of leno
are shown with four picks in a shed; and eight ends of plain, of which
the figure is usually formed, are shown. The design on point paper
for this would be as given in Fig. 149. Ordinary 8 × 8 paper is used,
although there are ten rows of needles. The card-cutter cuts the black
squares opposite the ground harness needle, and where the circles come,
he cuts so as to lift the doup in the next dent. Thus in the first
four cards for Fig. 149, the card-cutter would cut opposite the third
and fourth needles in the ground harness, and opposite the doup needle
for the next four ends. The plain would be cut in the ordinary manner
opposite the ground harness needles. A larger design for this harness
will be found in Chapter X.
Double-lift Jacquards are not yet used beyond the experimental form, as
the shaking cannot be done as easily as in a dobby with shafts, but we
have heard of the thing being done by knotting the harness above the
comber board and lifting the board a little when the cross is being
made. Messrs. Eccles, of Preston, some years ago obtained a patent for
lifting the standard ends by means of a third knife or griffe. The
additional knife was given half the lift of the other two, and its
function was to lift the standard ends half way when the doup ends were
crossing to the other side. This would, no doubt, enable the cross to
be made with ease in a double-lift Jacquard, but the principle is not
likely to be a great success.
The doups in leno Jacquards are very liable to wear out unless made
of very good material, and some experience is necessary before the
harnesses are worked satisfactorily.
An imitation of the fabric usually woven on this harness is sometimes
made by making one end cross three ends in the leno, and weave plain in
the figure. This can be done with an ordinary harness with a doup heald
in front lifted every other pick, on the same principle as in Fig. 144.