Dyeing and Printing

Dyeing And Printing 3(2+1)

Lesson 06 : Dyeing Methods

Related Terminology

Dyeing has been well defined as “applied chemistry” in fact the definition applies to the wet treatments preceding dyeing as well as to finishing process that follow it.

1. Material to liquor ratio: This ratio indicates the amount of liquor to be taken for dyeing a given weight of the material expressed in terms of M: L ratio. A ratio of 1:20 indicates that the weight of liquor should be 20 times the weight of material to be dyed.


2. Per cent shade: Textile materials after dyeing with a particular dye the amount of dye present on it after dyeing is expressed as a “per cent shade”. It is based on the weight of the material.


3. Per cent exhaustion: The amount of dye taken up by the material from the dye liquor at the end of dyeing is measured in terms of “Percent exhaustion”


4. Standing baths: When the percent exhaustion is very low, a large amount of dye remains in the dye bath and if not utilized, it is wasted. In many cases the bath is used again and again for dyeing the second and subsequent lots of material by replenishing the bath each time with fresh liquor containing the exact amount of the dye taken up by the preceding lot. Such baths are called “standing baths” and are used for the sake of economy.


5. Topping: A dyed surface when over-dyed with another colour from a different class of dye or from the same class of dye or with the same colour from a different class of dye from obtaining deeper shades or brighter shades or for obtaining “multicolored effects” at the cheaper rates, it is termed as topping.


6. Tailing effect: During course of dyeing on certain machines, there is a gradual weakening of the shade i.e., the shade starts becoming lighter or paler than the rest of the material resulting in light and dark dyeing. This effect is termed as “tailing effect”.


7. Stripping: when a shade comes out darker than the desired shade or when the dyeing becomes uneven then a part or whole of the dye stuff has to be removed from the dyed material. It is called as stripping.