A colourant/colour additive (British spelling) or colorant/color additive (American spelling) is a substance that is added or applied in order to change the
colour
Color (or colour in Commonwealth English; see spelling differences) is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorp ...
of a material or surface. Colourants can be used for many purposes including
printing
Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ...
,
painting
Painting is a Visual arts, visual art, which is characterized by the practice of applying paint, pigment, color or other medium to a solid surface (called "matrix" or "Support (art), support"). The medium is commonly applied to the base with ...
, and for colouring many types of materials such as
foods and
plastics. Colourants work by absorbing varying amounts of
light
Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...
at different
wavelength
In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats.
In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...
s (or
frequencies) of its
spectrum
A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...
, transmitting (if translucent) or reflecting the remaining light in straight lines or
scattered.
Most colourants can be classified as
dyes or
pigment
A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
s, 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 (e.g., linseed oil). The colour a colourant imparts to a substance is mediated by other ingredients it is mixed with such as
binders and
fillers are added, for example in
paint
Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...
s and
inks. In addition, some colourants impart colour through reactions with other substances.
Colourants, or their constituent
compounds, may be classified chemically as
inorganic
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''.
Inor ...
(often from a mineral source) and
organic (often from a
biological source).
Regulation
United States
In the US, the
Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...
(FDA) regulates colourants for food safety and accurate labelling.
See also
*
Food colouring
References
Color
{{Colour-stub
ja:色素
pt:Corante