Woven Fabrics - Fairchild Books

Figure 5.5
Various types of selvages: (a) Selvage
as produced by the shuttle loom.
Selvages made on a shuttleless loom
such as (b) fringe, (c) leno, and
(d) tucked-in selvage. c d
Various techniques are used to make the selvage
area stronger than the body of the cloth, including using
heavier warp yarns; more warp yarns per inch; plied
warp yarns; greater twist, if spun warp yarns; and different
weave. Because the selvage is usually constructed
differently than the body, it is fairly easy to identify.
If the selvage warp yarns are different from the
body warp yarns, their shrinkage characteristics may be
different. If the selvage warp yarns have greater shrinkage
during the finishing process, a tight selvage occurs,
resulting in the puckering of an area within several
inches of the fabric edge. This is a problem when the
material is unrolled on the cutting table and the cloth
does not lie flat.
Identifying Warp Yarns and Filling Yarns
One way to better understand the characteristics of
woven fabric is to know the differences between the
warp yarns and the filling yarns. Because fabric swatches
are mounted with the warp yarns vertically, it must be
determined which set of yarns is the warp so the mountings
are correct. More importantly, garments are usually
cut with the warp yarns running lengthwise, so the
FABRIC SCIENCE
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a
drapability of the fabric must be checked by the designer
to ensure that it meets the garment requirements. In
all cases, distinguishing warp from filling is necessary.
Finally, a textile expert making a complete analysis of
a cloth must be able to identify both the warp and filling
yarns in order to report such information as size,
amount of twist, and fiber content.
The following are some of the ways warp yarns can
be distinguished from filling yarns:
Selvage The warp yarns are always parallel to the
selvage.
Yarn sizes Usually the warp yarns are thinner, so
they abrade less as they pass through the loom and
rub against the various parts (e.g., heddles, reed). A
fabric that contains both filament yarns and spun
yarns usually has the filament yarns as the warp set.
Twist For the most part, spun warp yarns have more
twist than spun filling yarns. Because they usually
are thinner, more twist is necessary to enable them
to have sufficient strength to withstand the tensions
exerted on the yarns in weaving and in finishing.
b