Vat Dyes: Definition, Application, Classification & Properties

Definition of Vat Dyes

Vat dyes are a group of colors that are categorized according to how they are used. The method of dying in a vat or bucket is referred to as vat dyeing. The majority of dyes, including fiber-reactive, direct, and acid dyes, can be utilized for vat dyeing. Vat dyes can be used to color fabrics such as cotton, wool, and others.

Indigo, historically sourced from plants but now manufactured synthetically, is the original vat dye. The water-soluble glucoside in plants was first used to recover indigo, which was then used to dissolve the insoluble blue result in a wooden vat, a procedure that became known as vatting. This is where the name "vat dye" came from.

Application of Vat Dyes

The most crucial colors for dying cellulose and cotton fibers are vat dyes. In terms of washing, light, chlorine, and rubbing fastness, they are outstanding. Vat dyes are mostly used to color cotton fibers, which are primarily used to make denim for jeans. Wool and silk are both dyed using a tiny quantity of vat dyes. A colorant that is derived from indigo is known as a vat dye.

Classification of Vat Dyes

Anthraquinone vat dyes can be made, for instance, by reacting sulfonic acid with carboxylic acid to produce colors ranging from orange to blue.Fused ring polycyclic vat dyes are a diverse group of vat dyes that fall under this category and have carbonyl groups in them. These buildings' hue, makeup, and philosophy of color have drawn interest.The reduction of indigoid vat dyes with sodium dithionite results in their water-soluble form, which is still widely employed for dying denim.

Properties of Vat Dyes

Vat dyes are organic colorants.Vat dye cannot be applied directly to fabric since it is insoluble in water.On an alkaline media, vat dyeing is performed.The two physical forms of vat dyes are paste and powder.Since dyes are light-sensitive and ester groups are impacted, exposure to sunlight should be avoided while using dye baths.The major application of vat dyes is to color cellulosic fibers.These dyes enable the creation of a wide variety of hues.The vat dye has excellent washing stability, but poor rubbing stability.