Yarns

Question 1

What are the properties of a staple yarn?

Answer 1

1. Hairy.
2. Made from staple fibres.
3. Traps air and moisture.

Question 2

What effect does the twist give a yarn?

Answer 2

The twist holds the fibres together and gives strength to a yarn.

Question 3

What properties does a yarn with more twist have?

Answer 3

It is tighter, smoother and stronger.

Question 4

What properties does a yarn with less twist have?

Answer 4

It is more textured, and better suited for brushing.

Question 5

What happens to a yarn if it is twisted too tightly?

Answer 5

It untwists and snarls, creating crinkly crêpe yarns.

Question 6

What is a folded yarn?

Answer 6

Folded yarns are made by twisting together at least two single yarns.

Question 7

What is a cabled yarn?

Answer 7

A cable yarn is very thick. It is made from two or more folded yarns.

Question 8

How do you make a yarn balanced?

Answer 8

1. Fold a Z twist yarn and a S twist yarn together.

Or:

2. Fold two yarns with the same twist together, but make the folding twist opposite and equal to the yarns.

Question 9

What is a core yarn? What is a core-spun yarn?

Answer 9

1. Core yarns have a filament core, and a covering.

2. Core-spun yarns have the filament core covered with staple fibres, rather than another yarn.

Question 10

What are three uses of core yarns?

Answer 10

1. Clothes are given stretch by being made with yarns that have an elastane core.
2. Sewing threads have synthetic cores for strength, and a natural covering. The covering prevents the core from melting from the heat of the machine.
3. In woven fabrics, the covering can be selectively removed from the yarn to expose the core. This creates texture.

Question 11

Give two examples and descriptions of yarns with colour effects?

Answer 11

1. Mixture Yarns: Created by mixing different coloured fibres during spinning.
2. Jaspé Yarns: Created by folding two different coloured yarns together, or by folding together two yarns which react to dye differently.

Question 12

Give four examples and descriptions of yarns with structure effects?

Answer 12

1. Bouclé Yarns: Created using a special folding method which creates looped projections.
2. Slub Yarns: The yarn has areas which are thicker than the rest of the yarn. It is created during spinning or folding.
3. Chenille Yarns: Cut pile yarns that are soft and voluminous.
4. Crêpe: Crinkly yarns created from being highly twisted.

Question 13

What are the properties of a continuous filament yarn?

Answer 13

1. Smooth.
2. Made from filament fibres which run the length of the yarn.
3. Poor insulator.

Question 14

How can lustre effects be created in yarns?

Answer 14

1. Mixing matte and lustrous fibres together.
2. Using a clear or metallic plastic film like lurex.
3. Creating synthetic fibres with special cross-sections designed to enhance their lustre.

Question 15

What is denier or tex?

Answer 15

The size of a yarn.

Question 16

What are the effects of texturising yarns?

Answer 16

1. Increased volume.
2. Better insulator.
3. Softer handle.
4. Decreases lustre.

Question 17

Name and describe two methods of texturising?

Answer 17

1. False twist texturising: The yarn is heated to soften it, and then it is tightly twisted. When it is untwisted the deformation is permanently set as the yarn cools.
2. Air jet texturising: The yarn is passed through an air stream which causes loops and tangles.