Question

Indigo dye is an example of:
A. Azo dye
B. Vat dye
C. Dispersed dye
D. Basic dye

Answer 1

Hint: Indigo dye is a water insoluble dye that is applied to a fabric in a reducing bath which converts it to a soluble form, the color being obtained on the subsequent oxidation in the fabric fibers. From the above characteristics or the properties of the dye find out the category under which indigo dye can be listed as an example.

Complete step by step answer:
Vat dye is the dye that can be used only on cotton and it is a long continuous process which is carried out in a large vessel (a large vessel or tube used to hold liquid, especially in large industries) known as vat. These dyes are applied directly on the fiber and are generally insoluble in water. This water insoluble dye applies on a fabric in a reducing bath which converts it to a soluble form and the color being obtained on the subsequent oxidation in the fabric fibers. The properties of the vat dye are similar to that of the indigo dye which is a water insoluble dye that is applied to a fabric in a reducing bath which converts it to a soluble form, the color being obtained on the subsequent oxidation in the fabric fibers and hence indigo dye is an example of the vat dye.

Hence option (B) is the correct answer.

Note: Vat dye is named so the word vat means vessel. The dye takes their generic name from vatting, the vat dyes are naturally obtained coloring matter the ancient time and kept into wooden vat and made soluble in vat by the process of fermentation and hence it is called vat dye.