Vat Dyes
Vat Dyes

Vat Dyes

These types of dyes generally consist of a keto group in their structure and are made water-soluble by vatting. Their application process of vat dyes is quite similar to sulfur dyes. Mainly they are used for dyeing denim or jeans.

Properties:

  1. Produce an ample range of colors and amazing different shades
  2. Require alkaline conditions
  3. Found in powder and paste form
  4. Very Expensive dye
  5. Limited Uses
  6. Exhibit excellent fastness properties apart from the rubbing fastness.
  7. Natural coloring substances, not soluble in water

Mechanism:

These types of dyes contain four steps :

  1. Vatting: The insoluble dyes are converted into soluble leuco forms by reduction.
  2. Diffusion: The soluble leuco dyes get inside the cellulosic fiber.
  3. Oxidation: The soluble dyes are converted into insoluble form again.
  4. Washing-off: The unfixed dyes are removed from the surface.

Applications:  Cotton