Essential Colourant(s)
Many commercial products that are placed on the market are not just 100% of the substance responsible for the colour. They usually contain, in addition, quantities of other substances (generally referred to as additives) that improve the product’s application properties; e.g. its dispersibility, flow or flocculation resistance. Quite significant amounts of these additives may be present.
Agreed Definition
The essential colourant is a dye or pigment responsible for the colour of the product in the absence of additives.