1.4 Yarn properties

Question 1

Yarn:

Answer 1

A continuous strand of textile fibres, filaments or material in a form suitable for knitting, weaving or other methods of intertwining to form a textile fibre

Question 2

Thread:

Answer 2

A specific term for a strong, high-grade yarn used to join fabrics in the process of sewing

Question 3

Singles yarn:

Answer 3

A simple yarn formed from a single ply, the product of the first twisting operation

Question 4

Plied yarn:

Answer 4

A yarn in which two or more single strands are twisted together in one operation

Question 5

Twist:

Answer 5

The turns in a length of yarn – they may be clockwise (S) or anticlockwise (Z)

Question 6

Yarn number:

Answer 6

A measure of the fineness or size of yarn expressed as mass per unit length or length per unit mass, for example, denier, decitex and tex

Question 7

A measure of the fineness or size of yarn expressed as:

Answer 7

mass per unit length or length per unit mass, for example, denier, decitex and tex

Question 8

Yarn has been defined as a

Answer 8

continuous strand of textile fibres, filaments or material in a form suitable for knitting, weaving or other methods of inter-twining to form a textile fabric. If yarn is not to be used to make fabric, it may be called cords, ropes and thread.

Question 9

Thread

Answer 9

Thread is the term used for a strong, highly twisted yarn used to join fabrics while sewing.

Question 10

Staple or spunyarn

Answer 10

When short, staple fibres are twisted together, the yarn is referred to as staple or spunyarn.

Question 11

A single spun strand

Answer 11

A single spun strand, produced when fibres are twisted together for the first time, is called a singlesyarn.

Question 12

Ply-yarn

Answer 12

When two or more single strands are combined by a second twisting operation, a ply-yarn is produced. You may be familiar with a 3-ply or 4-ply knitting yarn.

Question 13

Yarn can occur in any one of the following forms:

Answer 13

A number of short, staple fibres twisted together (a spun yarn)
A number of filaments laid together without twist (a multifilament yarn)
A number of filaments twisted together (also a multifilament yarn)
A single filament (a monofilament yarn)

Question 14

The staple fibres come from:

Answer 14

The staple fibres can come from those natural fibres that are available only in short lengths such as wool, cotton or flax; or from manufactured fibres or silk fibres that have been cut into short lengths. Spun yarns need far more processing than filament yarns.

Question 15

1.4.2 Yarn size

The concept of linear density expressed by:

Answer 15

The fineness of different types of fibre or yarn is usually compared by looking at their lineardensity. Both denier and tex are used as units for expressing linear density.

Question 16

The denier is equal to:

Answer 16

The denier is equal to the mass in grams of 9 000 m of yarn. The lower the number, the finer the yarn will be. The denier system is usually used to measure silk and manufactured fibres, filaments or yarns.

Question 17

The tex is equal to:

Answer 17

The tex is equal to the mass in grams of 1 000 m of yarn. This is also referred to as the yarnnumber of a yarn, and is an indication of the yarn’s thickness.

Question 18

The linear density of single fibres or very fine yarns is often expressed in:

Answer 18

decitex

Question 19

The decitex is equal to:

Answer 19

The decitex is equal to the mass in grams of 10 000 m of yarn.

Question 20

The relationship between denier, tex and decitex can be illustrated by the following example:

Answer 20

If 9 000 m of a manufactured fibre, say nylon, has a mass of 9 grams, then it is a 9-denier fibre. One thousand metres of this fibre will then have a mass of 1 gram, making it a 1-tex fibre, while 10 000 m of the fibre will have a mass of 10 g, making it a 10-decitex fibre. Nylon pantihose are often made from a nylon fibre with a linear density of 9 denier, 1 tex or 10 decitex.

Question 21

In many knitting patterns, particularly the European ones, you may be told to use the following yarn:

Answer 21

480m length per 100g or

600m length per 100g.

Question 22

In South Africa, hand -knitting yarn is not always sold with the yarn size indicated by these yarn numbering systems. We know how thick a knitting yarn is by:

Answer 22

looking at the ply indication.

Question 23

A single- ply or singles yarn (known by machine knitters as industrialyarn)

Answer 23

very thin and two or three strands are used together, even on a knitting machine.

Question 24

Fine baby yarn is

Answer 24

sold as 3-ply yarn, but most hand knitters will not knit with yarn thinner than a 4-ply or even a double-knit.

Question 25

A 3-ply yarn is as thick as

Answer 25

three singles yarns and a 4-ply yarn as thick as four singles threads twisted together.

Question 26

1.4.3 Yarn twist

Answer 26

The twist that is produced during the spinning process binds the fibres together and gives the yarn strength.

Question 27

The amount of twist is indicated by:

Answer 27

the number of turns per inch (TPI) or turns per metre. The TPI needed to form the best possible yarn depends on the length of the staple fibres, the diameter of the yarn and the end use of the yarn.

Question 28

-Carded yarns with short staple fibres need a

Answer 28

higher twist (more TPI) than longer combed fibres.

Question 29

• A finer yarn requires

Answer 29

more twist.

Question 30

A low twist results in:

Answer 30

a soft yarn, often used as filling yarns of fabrics that are to be napped.

Question 31

Crepe yarns have a

Answer 31

high TPI (40 to 80), which makes the yarn lively and kinky.

Question 32

Yarns with a higher twist are

Answer 32

usually stronger (up to a point) but are also more expensive to produce.

Question 33

Yarns can be twisted with either

Answer 33

a right-hand twist (s-twist) or a left-hand twist (z-twist).