Colour Mixing and Colours: Primary, Secondary and Tertiary

Colour mixing is an essential part of colour theory and forms the basis for creating a wide range of colours from a limited number of basic colours. Understanding how colours are mixed and how primary, secondary and tertiary colours are formed is crucial for anyone who works with colour professionally, such as artists, designers and scientists. In this article, we discuss the different types of colour mixing and explain how primary, secondary and tertiary colours are created and applied.

Types of Colour Mixing

There are three main types of colour mixing: subtractive, additive and partitive mixing. Each type has unique properties and applications, depending on the context in which it is used.

Subtractive Colour Mixing

Subtractive colour mixing is based on mixing pigments or dyes. This type of mixing is often used in painting, printing and other applications where physical materials are mixed together. The primary colours in subtractive mixing are cyan, magenta and yellow. When these colours are mixed, they absorb (or 'subtract') certain wavelengths of light, resulting in the perception of new colours.

• Cyan + Magenta = Blue
• Magenta + Yellow = Red
• Yellow + Cyan = Green

When all three primary subtractive colours are mixed in equal amounts, black is theoretically produced. In practice, however, this often results in a dark, brownish colour, because pigments are never perfectly pure. This is why, in printing, black is added as a separate colour (known as the CMYK system) to achieve deep black tones.

Additive Colour Mixing

Additive colour mixing refers to the mixing of coloured light sources. This type of mixing is mainly used in digital displays, lighting and other technologies that work with light. The primary colours in additive mixing are red, green and blue. When these colours are combined, they add (or 'sum') different wavelengths of light together to create new colours.