Dye/Dyestuff

A substance may be called dye if it satisfies certain conditions:

1. It must have a suitable color.
2. It must be capable for being fixed to the fabric directly or with the help of certain agent called mordant.
3. When fixed, it must not be fugitive (the color must be fast to light and resistant to soap and water) and a certain extent to dilute acid and alkalis.
4. It should not be toxic.
5. Economical for commercial manufacture.

In other words, dyes are substances capable of coloring fabrics in such a manner that the dye can not be removed by rubbing or washing.

Characteristics/Properties of dye stuff:

1. The dye molecules of dye stuff must be colored.
2. It must contain chromophore group.
3. The chromophore groups may be different, such as, -N=N-, -N=O etc.
4. Must able to preparing dilute solution by dissolving water. i.e. solubility.
5. Must be power of entering dye molecules to the fiber from dye bath, i.e. substantibity.
6. It should have fastness properties.