Question

Which type of dyes are not used to dye nylon and polyester fibres?

• A. Vat dyes
• B. Basic dyes
• C. Disperse
• D. Insoluble azo dye

Answer 1

The correct option is A Vat dyes

Vat dyes are insoluble in water and cannot dye fibers directly. However, they can be made soluble by reduction in alkaline solution which allows them to affix to the textile fibers. Subsequent oxidation or exposure to air restores the dye to its insoluble form. Indigo is the original vat dye. These dyes are the fastest dyes for cotton, linen and rayon. They are used with mordant to dye other fabrics such as wool, nylon, polyesters, acrylics etc,.

Therefore Vat dyes are not used to dye nylon and polyesters.