Colourant


A colourant/colour additive or colorant/color additive is a substance that is added or applied in order to change the colour of a material or surface. Colourants can be used for many purposes including printing, painting, and for colouring many types of materials such as foods and plastics. Colourants work by absorbing varying amounts of light at different wavelengths of its spectrum, transmitting or reflecting the remaining light in straight lines or scattered.
Most colourants can be classified as dyes or pigments, or containing some combination of these. Typical dyes are formulated as solutions, while pigments are made up of solid particles suspended and are generally suspended in a vehicle. The color a colorant imparts to a substance is mediated by other ingredients it is mixed with such as binders and fillers are added, for example in paints and inks. In addition, some colourants impart colour through reactions with other substances.
Colourants, or their constituent compounds, may be classified chemically as inorganic and organic.

Regulation

United States

In the US, the Food and Drug Administration regulates colourants for food safety and accurate labeling.