Dyes
Dye is a synthetic and natural colouring matter that is employed in solution to stain materials particularly fabrics. All the coloured substances are not dyes. A coloured substance is known as a dye if it fulfills the subsequent conditions,
1. It should have an appropriate colour.
2. It may be lasting on the fabric either directly or with the help of mordant.
3. while fixed it must be fast to light and washing, that is it has to be resistant to the action of acids, water and alkalies, majorly to alkalies as washing soda and soap have alkaline nature.