Textile Yarns and Threads
Yarn is a long continuous length of interlocked fibres, suitable for use in the production
of textiles, sewing, crocheting, knitting, weaving, embroidery, and rope making.
Thread is a type of yarn intended for sewing by hand or machine.
Yarns can be described as single or one-ply; ply, plied, or folded; or as cord, including
cable and hawser types.
Single, or one-ply, yarns are single strands composed of fibers held together by at
least a small amount of twist; or of filaments grouped together either with or without
twist; or of narrow strips of material
Single yarns of the spun type, composed of many short fibres, require twist to hold
them together and may be made with either S-twist or Z-twist. Single yarns are used
to make the greatest variety of fabrics.
Ply, plied, or folded, yarns are composed of two or more single yarns twisted together.
Two-ply yarn, for example, is composed of two single strands; three-ply yarn is
composed of three single strands.
In making ply yarns from spun strands, the individual strands are usually each twisted
in one direction and are then combined and twisted in the opposite direction. When
both the single strands and the final ply yarns are twisted in the same direction, the
fibre is firmer, producing harder texture and reducing flexibility. Ply yarns provide
strength for heavy industrial fabrics and are also used for delicate-looking sheer
Cord yarns are produced by twisting ply yarns together, with the final twist usually
applied in the opposite direction of the ply twist.
Cable cords may follow an SZS form, with S-twisted singles made into Z-twisted plies
that are then combined with an S-twist, or may follow a ZSZ form. Hawser cord may
follow an SSZ or a ZZS pattern. Cord yarns may be used as rope or twine, may be
made into very heavy industrial fabrics, or may be composed of extremely fine fibres
that are made up into sheer dress fabrics.
Novelty yarns include a wide variety of yarns made with such special effects as slubs,
produced by intentionally including small lumps in the yarn structure, and man-made
yarns with varying thickness introduced during production.