Dyes And Colouring

Question 1

State the difference between dyeing and printing.

Answer 1

Dying- the production of a single, uniform colour of textiles
Printing- production of multiple copies of designs in multiple colours

Question 2

State the three stages of printing process.

Answer 2

Transfer, fixation, wash off

Question 3

State the name of chemical needed to attach pigments to the fibre materials.

Answer 3

Binder

Question 4

Describe what ‘Mass coloration’ means

Answer 4

When pigments or dyes are mixed with the molten polymer before extrusion

Question 5

State 3 features of late stage dyeing

Answer 5

• too late to correct unlevelness
• garments may be dyed to popular fashion colours
• quick response to orders is possible

Question 6

State the solvent used as a printing paste ingredient.

Answer 6

Water

Question 7

State the pH condition of the dye bath when dying wool using acid dye.

Answer 7

Acidic condition

Question 8

Explain what is meant by ‘water-repellent’.

Answer 8

Fabric is relatively resistant to absorption, surface wetting, or penetration of water

Question 9

Name the most important form of industrial fabric printing.

Answer 9

Screen printing

Question 10

Name the most economical method of printing for short runs.

Answer 10

Digital printing

Question 11

Out of dyes and Pigments, which one is used more commonly in printing of textiles?

Answer 11

Printing

Question 12

Name the 4 types of screen printing?

Answer 12

Hand, rotary, semi-automatic, and fully-automatic flatbed

Question 13

Reactive dyes are water soluble, is it used dying cotton or polyester?

Answer 13

Cotton

Question 14

Disperse dyes are only partially soluble in water, is it used for dyeing wool or polyester?

Answer 14

Polyester

Question 15

Out of rotary screen, flat-bed screen and digital printing, which one gives the fastest production for long runs?

Answer 15

Digital printing is the fastest

Question 16

What kind of dye is best for protein fibres?

Answer 16

Acid dye

Question 17

What dye is best for cellulosic fibres?

Answer 17

Reactive dyes

Question 18

What kind of dye is best for man-made fibres?

Answer 18

Disperse dye

Question 19

When can fibres be dyed? (5)

Answer 19

Polymer melt (man made)
Loose stock
Yarn
Fabric
Garment

Question 20

What is meant by loose stock?

Answer 20

Loose stock is the raw material, after the removal of impurities, but before processing

Question 21

Describe the rotary screen printing process

Answer 21

• fast continuous production
• uses cylindrical screens
• these rotate in contact with fabric
• print paste is fed from inside screens, forced through with squeegee
• very economic for long runs