284   FABRICS
Fibers. Fabrics are usually made from fibers of silk, wool,
cotton, linen, and rayon or other synthetic products, alone or in
combinations. When selecting fabrics the purchaser should in-
quire about their fiber content.
Yarns. Fibers are spun into yarns which vary in size, evenness,
smoothness, elasticity, strength, amount of twist, and length of
fiber. A purchaser should untwist and examine separate strands
of yarn or threads drawn from fabrics. A yarn that breaks easily
is poor; short or coarse fibers usually indicate weakness, whereas
round, hard, well-twisted yarns are strong. Sometimes durability,
however, is not so important as beauty or novelty.
Construction of Fabrics. Methods of making the fabrics help
to determine their durability and appearance. Weaving is the
principal method although a few fabrics are made by other proc-
esses. Jersey is knitted, nets consist of knotted threads, and some
articles are braided. Felt is made of pressed matted fibers. Fiber-
less fabrics are made from fluids which become solidified in sheets.
Weaving. Methods of weaving differ, but in all of them the
warp threads, which run the length of the fabric, make a support
for the weft yarns, which are interwoven through them back and
forth from selvage to selvage. The three types of simple weaving
that are the basis for all others are the plain weave, as in taffeta,
the twill weave, always diagonal in effect as in serge or denim, and
the satin weave. Novelty weaves with beautiful textures are made
by combining coarse and fine yarns or unusual twisted yarns.
Patterns are made by lifting the threads in groups.
Dyeing. Fabrics can be dyed at different stages in their manu-
facture. Sometimes raw fibers are dyed before the yarn is spun;
sometimes the finished yarn is dyed; often the entire fabric is dyed
after it is woven. Manufacturers' labels are helpful in determin-
ing color permanence.
Printing. Patterns are usually printed on fabrics by a series of
copper rollers, each of which prints one color. In some fabrics
the pattern is printed on the warp thread only. In discharge print-
ing a bleach removing the color in the shape of a pattern is applied
to a plain material. Resist printing* is done by means of a sub-
stance which prevents the dye from acting in the places where it
is applied.