Basic Colours Explained – Why Black is K
Black
The black colour can be defined as the absence of all other colours, as compared to white, which is a combination of all colours. The science behind the colour of black lies in the types of colour which are reflected back. Black is the absorption of all of the colours, with no colours reflected back to the human eye. Comparitively, white will reflect the entire colour spectrum back to the human eye, which then recombines them into the colour that we see and recognise as white.
Black can be printed by combining 100% of the Cyan, Magenta and Yellow colours (making a separate black cartridge redundant). However, this method has its drawbacks as often the colour produced is closer to grey than a true black. The benefits of a separate black cartridge also lie in its ability to be swapped out without wasting left-over ink from the other colours in that cartridge, as black ink is the predominant form of ink used.
To produce better results the four colour printing method CMYK is used where black is K and the fourth cartridge colour. This stands for Cyan, Magenta, Yellow and Black. K is used instead of B in this method to avoid confusion with the Red, Green, Blue (RGB) acronym where B is blue. The K used instead is derived from the German word ‘kohl’, meaning coal.
Cyan
Cyan is also called process blue and is one of the subtractive primary colours used in the CMYK or CMY colour methods (where CMY is just CMYK where black is derived from mixing the three colours, as explained above). This colour is primarily blue, with some green in it.
For printers using ink cartridges Cyan is either inserted as one of four cartridges (one for each of the Cyan, Magenta, Yellow and Black) or as a combined ink cartridge with Yellow and Magenta.
Magenta
Magenta is also called process red and is the second of three subtractive primary colours used in the CMYK and CMY methods. The magenta colour is greenless, meaning it absorbs all wavelengths of green light and predominantly red with a tinge of blue.
Like Cyan, Magenta is either inserted as one of four cartridges (one for each of the Cyan, Magenta, Yellow and Black) or as a combined ink cartridge with Yellow and Cyan.
Yellow
Yellow is the third and final subtractive primary colour used in the CMY and CMYK printing methods. Yellow is blueless, meaning that it absorbs all wavelengths of blue light.
Like the two other subtractive primary colours, Yellow is either inserted as one of four cartridges (one for each of the Cyan, Magenta, Yellow and Black) or as a combined ink cartridge with Cyan and Magenta.
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