The dyeing process takes place in three distinct phases:
Adsorption and Diffusion
The reactive dye is adsorbed onto the cellulose surface and then diffuses into the fiber matrix.
Fixation
If conditions are favorable (high temperature and/or high pH), the reactive dye reacts with active sites in the cellulose during this phase (fixation), resulting in a strong covalent bond.
Washing Off
To obtain the required fastness properties, all these forms of unfixed, adsorbed dye molecules must be washed off the fiber.