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Grammar of textile design (Volume c.2) online

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hottom-doup harness, they will be woven face downward. This
warning is necessary to prevent confusion by the apparent in-
consistency between the cloths, as here represented, and their
respective designs, which latter, being prepared for bottom -doup
harnesses, represent the reverse side of cloth. The dotted lines



^06



GBAMMAE OF TEXTILE DESIGN.



on the design (Fig. 418) are not essential to its construction,
but are merely introduced to indicate doup warp ends as they
will appear on the face side of cloth, so that their working may
be easily followed. On examining that design and shedding
plan, it will be seen that a cross shed is formed for two con-



Design (A).



Shedding
Plan ^C).



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Cross Shed

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Draft (B).

Fig. 418.— Design, Draft and Shedding Plan for Net Leno Fabric represented
by Fig. 417.

secutive picks out of every six, by raising the front standard
and doup healds, and slackening the easer ; whilst the ground
healds operate as indicated. The two consecutive picks midway
between those in the cross sheds are inserted in ojjen sheds, for
which doup warp ends may be either raised or left down by



GAUZE AND LENO FABRICS.



207



their respective back standard healds, as required. When,
however, the single picks of weft, that intervene between those
in the cross and open sheds, are inserted, all doup ivarp ends
must remain down. The peculiarity of these fabrics (that was
referred to in §§ 97 and 98) of doup threads appearing to be on
the normal side of standard warp ends, when they are actually
on the crossed side of those threads, and vice versa, is also observ-
able in this variety of leno fabrics.

§ 101. Figs. 419 and 422 are reproductions of other examples
of figured "net leno " fabrics in which the figuring is developed
by means of only one doup and one front standard heald,




Fig. 419. — Net Leno Fabric, woven by means of One Doup and One Front
Standard Heald, and Five Back Standard Healds, for which the
Design, Draft and Shedding Plan are given in Fig. 420.

operating in conjunction with several back standard healds, and
two or more healds to govern ground warp ends to produce the
foundation texture. In these examples doup warp ends are
arranged in pairs disposed at regular intervals apart, for the
production of all-over designs. The threads of each pair cross
their respective standard ground warp ends in reverse directions,
so as to develop a neat diamond formation, excepting where
doup threads lie straight and parallel on their crossed side of
standard warp ends. The present examples will serve to in-
dicate the general character of designs suitable for these fabrics,
and also the fair scope they offer to a designer in the creation of



208 GRAMMAK OF TEXTILE DESIGN.

effective patteras. The example of cloth represented in Fig. 4cl9
has a foundation texture of the plain weave, consisting of fine
ground warp ends (taped in pairs) picked with fine weft. Doup
warp ends, of two-fold yarn, each cross three pairs of standard
threads, and are governed by five back standard healds, in
addition to a front standard and a doup heald. It has required
a different drafting of doup threads through the back standards,
but not of ground warp ends, which are governed by two healds
that rise and fall alternately for consecutive picks throughout.

The design, draft and shedding plan (arranged for a bottom-
doup harness) required to weave the example of cloth (Fig. 419)
are given at A, B and C respectively (Fig. 420). The pattern
repeats on eighty-four pairs of ground warp ends (represented
in the design and draft as single threads) and twenty-eight doup
warp ends and sixty -four picks of weft. Doup warp ends are
drawn through the back standards so as to form a reversed
pointed draft. The method of drafting doup warp ends for
these examples of cloth marks a distinctive and important
feature of interest in their construction. As will be seen, on
consulting the draft (B, Fig. 420), doup warp ends are disposed
in pairs, with the two threads constituting a pair crossing from
their normal to their crossed side in reverse directions simul-
taneously, and drawn through heald eyes in the same back
standard. For example, the central pair of doup threads are
drawn through the fifth back standard heald, and constitute one
extreme point of the draft ; whilst the first and last doup threads
in the pattern, which cross in reverse directions, both pass
through the second back standard, and constitute a pair forming
another point in the draft.

This arrangement of the draft causes the threads of each pair
to converge and lie side by side, quite straight and parallel with
each other, luhen on their crossed side, but to diverge when
raised by their back standard healds. Thus, by forming cross
and open sheds at regular intervals (of picks) apart, the neat net
leno diamond formation, characteristic of the present examples, is
produced. On examining the design and shedding plan, it will
be observed that an open shed is formed for two contiguous
picks (the third and fourth) out of every eight picks, and a cross



GAUZE AND LENO FABRICS.



209




igagasag^ ^ ^m g



210



GRAMMAR OF TEXTILE DESIGN.



shed for the intermediate pairs of picks (the seventh and eighth),
whilst the ground healds rise alternately for consecutive picks
throughout, to produce the foundation texture. Owing to the
different rates of contraction of doup warp ends, with this
design, those threads will require to be contained upon three
separate warp beams, in addition to one containing ground
warp ends.







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Fig. 421. — Net Leuo Fabric, Avoveu by means of One Doup aud One Front
Standard Heald, and Eight Back Standard Healds.

§ 102. The cloth represented in Fig. 421 shows a slight varia-
tion from the previous examples in having doup w^arp ends
more widely dispersed upon a muslin ground texture of plain
cloth. In this example, each set of doup warp ends consists of
two pairs of threads of two-fold yarn, crossing their respective
standard w^arp ends in reverse directions. Tlie ground warp
ends, which serve as standard threads for each doup warp end,



GAUZE AND LENO FABKICS.



•211



consist of four threads taped in pairs, whilst the intervening
stripes of plain cloth consist of eleven single warp ends. This
example has required eight back standard healds to produce the
pattern which it contains, with consecutive pairs of doup
threads drawn through them in regular succession to form a
straight-through draft. The leno effect is developed by forming
two cross sheds in succession, for single picks, at intervals of six
picks, and by forming an open shed, where required, also for




Fig. 422. — Net Leuo Fabric, woven by nieaus of Two Doup and Two
Front Standard Healds, with Two Back Standard Healds operating
in conjunction with each Doup Heald, and its Front Standard Heald.

single picks, midway between two cross sheds, but only at
intervals of twelve picks ; thus : 1 [cross shed), 2, 3, 4, 5, 6, 7
(cross shed), 8, 9, 10 (open shed), 11, 12, and so on. It is im-
perative, in order to create harmonious leno effects in fabrics of
this variety, that cross and open sheds should be formed in a
rhythmical order, and not at irregular intervals of picks apart.
It may also be observed that if doup warp ends cross their
standard threads in the same direction uniformly (as in Fig. 418),
it is advisable to draw them consecutively through successive



212 GKAMMAE OF TEXTILE DESIGN.

back standard healds ; but if they cross in reverse directions (as
in Fig. 420), they should be drawn through the back standards
in pairs, as indicated in the draft (B).

§ 103. It was stated in § 95 that more than one doup heald,
each to operate in conjunction with several back standard healds,
may be employed to increase the scope of the type of leno har-
ness under present notice. The example of cloth represented by
Fig. 422 has required two doup healds, each operating with two
back standards. In this example doup threads lie straight when
on the normal side of their standard threads, as in ordinary leno
fabrics. This specimen was submitted for analysis at the City
and Guilds Second Year's Examination (1905) in Cotton Weaving.



Leno Specialities.

§ 104. In the production of gauze and leno fabrics by the
methods previously described in this chapter, it is impossible to
effect a crossing of any two or more warp ends with each other,
unless the crossing threads are severally contained in the same
dent of the reed : hence, a crossing may not be made with
warp ends that are separated by a reed wire. This restriction,
however, may be avoided by the use of specially adapted leno
weaving devices, whereby the crossing of warp ends is accom-
pHshed by means of doup healds situated between a disappearing
beating-up half-reed, or comb, and an ordinary deep stationary
reed, situated between the doup healds and regular healds, as
clearly represented in Fig. 430. Such arrangement of healds
and reeds enables warp ends to be crossed either separately, or
in groups, in almost any conceivable manner, irrespective of the
order in which they pass through the dents of the stationary
reed, during weaving. Thus, it is possible to effect a crossing
of threads, en masse, that extend over several dents, without
those threads crossing or douping loith the intermediate warp
ends which they simply pass over. The doup harness may be
either a top or bottom-doup harness, or it may be a combina-
tion of both these arrangements. Also, warp ends may be
passed through and governed by two separate and distinct doup
slips of the same or different lengths, to effect a crossing to the



GAUZE AND LENO FABRICS.



213



right or left over a smaller or a greater number of threads, as
reqmred. This system of leno weaving affords almost illimit-
able opportunities to a capable designer in the creation of
decorative effects of a very ingenious and pleasing character,
as exemplified in Figs. 423 to 429, which are full-size photo-
graphic reproductions from actual pieces of cloth representing
a few typical examples of this particular variety of leno fabrics.
§ 105. The construction of these fabrics will be better un-




FiG. 423.



Fig. 424.



Special Leno Effects produced by a system of crossing Warp Ends in front
of the Reed.



derstood if the reader is informed of the mechanical devices
employed in their manufacture, of which there are several
modifications that differ chiefly in details of construction and
operation. With the object of conveying that information to
students, a diagram representing a part sectional elevation of a
loom equipped with Whitehead and Wood's modification of a
special leno weaving device is given in Fig. 430. With a view
to better demonstrating the operation of this device, the sley
and its appurtenances are represented at both the backward



214



GRAMMAR OF TEXTILE DESIGN .



and forward extremities of their movement by full lines and
dotted lines respectively. As indicated in the diagram, instead
of fixing a reed in its usual place in the sley, a reed 0, of un-
usual depth, is placed between the regular healds N, and the
doup healds P, and permanently fixed to brackets secured to
the loom framing. The function of the stationary reed is simply
to effect an even distribution of warp ends over the required

Fig. 425.





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218



GEAMMAR OF TEXTILE DESIGN.



of a half-reed, a lappet loom is furnished with one or more
needle bars to control figuring or "whip" threads, and these
bars are moved laterally for figuring purposes, as well as verti-
cally, to insert figuring threads into the warp sheds.



Full-cross Leno Fabrics.

§ 106. In all the examples of leno fabrics herein described,
doup threads make only a partial or half turn around their
respective standard threads : that is, they pass from one side to








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Fig. 431. — Full-cross Net Leno Fabric in which Doup Warp Ends are
twisted completely around Standard Warp Ends, at intervals of
four Picks to the Right and Left alternately.

the other side of those threads, and then return to the same
side, on different picks of weft, and do not completely twist
around them. Sometimes, however, leno fabrics are produced
in which doup threads are caused to completely encircle their
standard threads, and thereby produce a full crossing or twist
with them, as exemplified in an actual specimen of cloth illus-
trated by Fig. 431, in which pairs of black doup threads cross
or twist with pairs of whits standard threads, to develop the
striped leno effect shown at A. This unusual system of cross-
ing is accomplished by causing the doup slips to completely



GAUZE AND LENO FABEICS. 219

wrap around the standard threads, as they pass from the doup
threads to the heald stave on which they are contamed. Thus,
whenever a shed is formed, whether it be an open or a cross
shed, the doup threads are either up or down always on the
same side of their respective standard threads ; thereby causing
them to make a full crossing, as described.

Relative Merits of a Top and a Bottom Doup Harness.

§ 107. Throughout this chapter frequent reference has been
made to the alternative methods of placing doup slips above or
beloio warp ends, for the production of gauze and leno fabrics,
both of which systems are described in ^ 90. Since the choice
of position is quite arbitrary, it is not surprising that the
opinions of practical men, respecting the relative advantages of
both systems, should vary according to their prejudices and
varied experiences, and that some advocate one system and
some the other. From this circumstance, it is quite evident that
oach method possesses some advantage over the other, at least
for certain classes of fabrics ; otherwise, one of the two would
long since have been discarded in favour of the better system.
It will, therefore, be both interesting and profitable to briefly
oompare the relative merits of each system, and to state which it
may be more expedient to adopt, under different circumstances.

For the production of net leno and similar fabrics containing
thick net doup threads or cords, that are chiefly displayed on
one side of cloth, it is more expedient to employ a top-doup
harness. By that arrangement, such fabrics are woven face side
upward, thereby enabling a weaver to more readily detect im-
perfections in cloth during weaving. Another great advantage
to a weaver, of doups being placed above warp ends, is that they
are more accessible and therefore more easily repaired, or else
replaced by new ones, which frequently becomes necessary, jn
consequence of doup slips rapidly wearing out. In the event of
breakages, however, top-doup slips are liable to prove a source of
serious trouble to a weaver by hanging dov/n and becoming en-
tangled with warp ends, thereby involving the risk of breaking
them, and causing faults in cloth. Another disadvantage of



220



GEAMMAE OF TEXTILE DESIGN.



top doups is in respect of shedding. If a negative acting dobby
and a spring under motion are employed to operate a top-doup
harness, it is more difficult to obtain a good lower half of
the warp shed, in consequence of healds being depressed and
held down negatively, by means of springs. This arises in
consequence of the abnormal tension of doup warp ends during
the formation of both cross and open sheds, whereby they tend
to rise a little above the surface of the shuttle race-board, in-
stead of lying well down upon it, as a shuttle is transmitted



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Fig. 432.— Check Gauze Fabric.

through the warp shed. If bottom doups are employed, cross-
sheds are formed by raising front standard and doup healds
positively by the dobby, whereby better and clearer warp sheds
are formed. In consequence, however, of the cloth being woven
face downward by them, as previously described in § 100, they
are not generally used for net leno and similar fabrics, but are
chiefly confined to the production of those fabrics not containing-
thick net doup threads, and of which both sides are exactly
similar, such as that illustrated in Fig. 432. Also, the renewal



GAUZE AND LENO FABRICS. 221

of bottom-doup slips is much more difficult than the renewal of
top doups ; but if bottom doups break, they fall away from warp
■ends, and do not, therefore, become entangled with them.

Relative Merits of Different Types of Dobbies for
Gauze and Leno Fabrics.

§ 108. In the production of gauze or leno fabrics it is desir-
able to effect a crossing of warp ends with the least possible
straining or chafing of those threads. This desideratum is the
principal stumbling-block to the successful adoption of dobbies
that are unprovided with auxiliary attachments which specially
adapt them for leno weaving. To avoid excessive straining and
chafing of warp ends, whilst in the act of crossing each other,
one of two conditions must exist, namely, either the crossing
threads must be quite level at the commenGement of crossing,
that is, when rising and falling warp ends meet in the centre of
the warp shed ; or else doup threads must pass either from the
upper or else the lower part of the warp shed, when the crossing
takes place, according to whether a toj) or a hottom-diOVi^ har-
ness, respectively, is employed. It will now be manifest, there-
fore, that either a '' closed-shed " dobby, or one that will produce
the conditions just described, is better adapted than an " open-


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Online LibraryHarry NisbetGrammar of textile design (Volume c.2) → online text (page 13 of 19)