Vat dyes is a series of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. The original Vat dye is indigo, once obtained only from plants but now often produced synthetically.

Properties

Vat dyes are insoluble in water. They offer high color fastness, which is uncommon in other dye classes. On the other hand, Vat dyes tend to have poor rubbing fastness, but this can be mitigated with special treatments to the fabric. Indigo is subject to major crocking (i.e., rubbing the dye off onto other items) unless it is applied carefully. This means that dipping many times in a weaker dye-bath is more preferred than to dip once in a stronger dye-bath.

Applications

Vat dyes are specially used for military uniforms owing to outstanding fastness properties, earth tone shade, and near infrared (NIR) camouflage. They are also commonly used for school uniforms and hospital fabrics