Classification of Dyes
Dyes can be classified in several ways, each class has a very unique chemistry, structure and particular way of bonding. Some dyes can react chemically with the substrates forming strong bonds in the process, and others can be held by physical forces. Some of the prominent ways of classification are given below
- Natural / Synthetic
- Organic / Inorganic
- By area and method of application
- Chemical classification - Based on the nature of their respective chromophores.
- By nature of the Electronic Excitation (i.e., energy transfer colorants, absorption colorants and fluorescent colorants).
- According to the dyeing methods
- Anionic (for Protein fibre)
- Direct (Cellulose)
- Disperse (Polyamide fibres)
US International Trade Commission has advocated the most popular classification of dyes. This system classifies dyes into 12 types, which are given below:
| Group | Application |
| Direct | Cotton, cellulosic and blended fibres |
| Vat dyes | Cotton, cellulosic and blended fibres |
| Sulphur | Cotton, cellulosic fibre |
| Organic pigments | Cotton, cellulosic, blended fabric, paper |
| Reactive | Cellulosic fibre and fabric |
| Disperse dyes | Synthetic fibres |
| Acid Dyes | Wool, silk, paper, synthetic fibres, leather |
| Azoic | Printing Inks and Pigments |
| Basic | Silk, wool, cotton |