Most colour effects can be achieved in several different ways. As an example, a solid coloured fabric could be made by dying loose fibre in a single colour, spinning that fibre into yarn and using that yarn to tuft rugs. However the same fabric could be made by immersing white yarn into the dyebath and using that yarn to form the fabric.
Likewise a heather could be made by dyeing two batches of loose fibre different colours and blending the fibres before spinning the yarn, but it might also be achieved by immersing a blended fabric containing fibres with different dying behaviours into a dye bath that contains dyes from different dye classes.
The textile material being dyed, can be the product of any stage in the formation of the textile from loose fibre to end use item. The type of dying equipment used depends on the material. The dye can be circulated within the equipment while the textile can be moved through a stationary dyebath, or both can be circulated.
As a rule, when the same colour effect can be achieved at different stages of manufacture, the material closest to completion of the product is immersed in a dyebath.