yarn making, twist and ply

ADDING TWIST AND CREATING PLIED YARNS

yarn twist
The reason for adding twist in staple-spun yarns is to
bind the staples together, and to give strength to the yarn.

In processing continuous filament yarns, twist is not such an important issue, the filaments are only twisted just enough to hold the fibres together.

The two important factors of twist are, the direction of the twist and the angle of the twist.

S Twist

the direction of twist

Twist can be inserted in either of two directions, clockwise or anti-clockwise.
The directions are known as the 'S' twist and the 'Z' twist repectively.

The majority of single yarns are spun with a 'Z' twist.

In single yarns the direction of twist does not affect the behaviour of the yarn.

Z Twist

Perhaps it would be appropriate at this point,
to explain that a single yarn is not necessarily the same as a 1ply yarn.
A single yarn is when twist has been added to the drawn slivers of fibres
in order to hold the fibres together to form a yarn.
A plied yarn is when 2 or more single yarns are twisted round each other.
For most knitting purposes a single yarn would not be strong enough, the fibres would pull apart.
Knitting yarns have been plied, if you look carefully at a 1ply yarn, you will find two single ends twisted round each other.

when yarns are plied, the direction of twist is very important.

It is usual for the ply twist to be in the opposite direction to that of the twist used in the original spun single yarn.

'S' singles with 'Z' ply, 'Z' singles with 'S' ply
will produce a balanced yarn.

'S' singles with an 'S' ply, or 'Z' singles with a 'Z' ply
will produce a lively yarn with a bias twist and a tendancy to snarl and snag.

a balanced yarn plied with a 'Z' twist,
will be smooth, firm and tight, with resistance to abrasion,
good for weaving yarns and worsted wools, also most petit-point embroidery yarns are 'Z' twist.

a balanced yarn plied with an 'S' twist,
will be soft and bulky,
ideally suited to hand knitting

	the angle of twist The angle of twist is of vital importance and will determine how the resulting yarn will behave. A low angle of twist will produce yarns that are relatively soft and bulky (used for hand-knitting). A high twist angle will produce a strong, hard firm yarn (good for weaving).
low angle twist		high angle twist

A very high, over-twisted angle will produce a yarn which although weaker, is very hard, and twist lively.
A yarn that will 'snarl' easily when not held under tension,
(can be used with a base yarn to create decorative and fancy yarns).

for information about plied, folded and fancy yarns
click 'next page'

twist and ply