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Table 4.1 Comparison oF sTreTCh Yarns<br />
Yarn Type<br />
Textured<br />
yarns<br />
provide softer and more gentle shape control (moderate<br />
recovery force) than covered yarns.<br />
Covered Elastic Yarns Covered elastic yarns are<br />
monofilaments that are wrapped or covered with a spun<br />
or filament yarn to hide the elastomeric yarn. Covered<br />
yarns tend to be thick and heavy and are used in powerstretch<br />
fabrics. In general, they provide firmer and more<br />
powerful shape control (high recovery force) than bare<br />
elastic yarns.<br />
Core-spun Yarns Core-spun yarns have a central filament<br />
core of spandex with staple fiber that has been<br />
spun around the core. The core in the center does not<br />
appear on the yarn surface, so the hand, texture, and<br />
appearance are identical to what the spun yarn would<br />
be without the core center. Core-spun elastic yarns are<br />
used in comfort stretch fabrics because they possess very<br />
low recovery force. These yarns can be spun very fine<br />
and thus provide elasticity without the bulk usually<br />
associated with other types of stretch yarns. Stretch<br />
chino, a popular cotton sportswear fabric used for tennis<br />
shorts and other active sportswear, is made from corespun<br />
cotton yarns. Core-spun stretch yarns are the most<br />
expensive of all stretch yarns.<br />
Textured Yarns Textured yarns are the most widely<br />
used of the comfort stretch yarns. The “ease” or “give”<br />
these yarns contribute to the fabric is a quality many<br />
consumers find attractive.<br />
High-Bulk Yarns<br />
Stretch Fiber<br />
Component Stretch Type<br />
Nylon or<br />
polyester<br />
High-bulk, also called hi-bulk or turbo-bulk, yarns are<br />
acrylic spun yarns that are specially processed to yield<br />
lofty, bulky, and soft yarns without stretch.<br />
These yarns are produced by a unique process that<br />
involves spinning yarn by blending acrylic fibers of high<br />
Recovery<br />
Power Uses and Features<br />
Comfort Low Blouses, sportswear, stretch pants, hosiery, polyester<br />
men’s socks. Polyester has a tendency to pill.<br />
Bare elastic Spandex Power Moderate Lightweight foundations, swimwear, athletic wear—<br />
gym clothing, bike shorts.<br />
Covered<br />
elastic<br />
Spandex or<br />
rubber<br />
Core spun Spandex Comfort Very low<br />
to low<br />
Power High Heavy foundations, elastic bandages, surgical<br />
stockings, athletic supporters. Rubber has higher<br />
power and recovery than spandex, but poor shelf<br />
life—it begins to decay in one year.<br />
YARNS AND SEWING THREADS<br />
A 79 F<br />
Active sportswear, stretch denim.<br />
and low potential shrinkage. When the finished yarn is<br />
treated with boiling water or steam, the high-shrinkage<br />
fibers contract and move to the center of the yarn, forcing<br />
the low-shrinkage fibers to buckle, which forms a<br />
yarn that is greater in diameter than the original and<br />
has more loft and bulk. Some high-bulk yarns are bulked<br />
(boiled or steamed) in yarn form, and others are bulked<br />
in garment form (e.g., knitted sweaters).<br />
<strong>Fabrics</strong> made of high-bulk acrylic yarns feel soft and<br />
luxurious, and frequently have the hand and appearance<br />
of high-quality worsted. They have the disadvantage of<br />
tending to pill easily, and they should be checked carefully<br />
for conformity to current flammability regulations.<br />
Novelty Yarns<br />
Novelty yarns, sometimes also called fancy yarns, are<br />
yarns that are not of uniform thickness throughout their<br />
length, but have deliberate irregularities on their surfaces<br />
(Figure 4.12). These irregularities may be knots,<br />
bumps, curls, or similar effects.<br />
The naming of novelty yarns is confusing, however.<br />
Because there is no established terminology for novelty<br />
yarns, their names are often used interchangeably. Novelty<br />
yarns, or fabrics containing novelty yarns, should<br />
never be purchased on the basis of yarn name alone,<br />
but only when accompanied by samples. Typical novelty<br />
yarns are slub, thick and thin, spiral, flock, and bouclé.<br />
(See Figure 4.13.)<br />
Novelty yarns give fabrics made from them interesting<br />
and decorative surface effects. Using novelty yarns<br />
is one means by which textile designers can create cloth<br />
with raised or nubby surface textures as distinguished<br />
from the usual flat surface of most textile materials.<br />
<strong>Fabrics</strong> made from most novelty yarns are not durable<br />
and are especially susceptible to wear from abrasion<br />
or rubbing. The parts of the yarn exposed beyond the
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