By Steffen Andersen · 19. May 2020
The CMYK colour system is by far the most used colour system for offset and digital print. Which means that it is a colour process that you meet often in your day, it can be the flyer with a political statement or a poster promoting a concert nearby, but it could also be the paper printed from your own printer. Would you like to know more about what CMYK means, how the colouring process works, and how the colours are displayed on printed articles? Then look no more, we will cover all of this in the following article.
The colour system is called CMYK is because CMYK stands for Cyan, Magenta, Yellow and Key. So the name represents the 4 primary colours in the colour process that are mixed together into almost 70% of all the colours that are visible for the human eye. CMYK colours can both be referred to as 4-colour process and full-color printing, the reason why it is called 4-colour process, is because it uses 4 colours as primary colours. The reason why it is called full-colour printing is that the process allows you to use as many colours in the design, without paying anything extra.
You might ask yourself why are these four colours the base colours of CMYK, why not more colours, so it would be able to match more than 70% of all colours? The reason for these colours is affordability since Cyan, Magenta, Yellow, and Key are the four colours that together allow us to get the widest colour spectrum for print. It would of course have been larger with more colours, but the prices would also have been higher in comparison.
Today it is though a reality that more large printing companies and especially in industrial print, have printing machines that can print with up till eight colours. The primary reason why this is a reality is to increase the colour spectrum and especially when it comes to brighter colours. These companies would though normally use Pantone colours as there colouring system.
When saying the colours are mixed together, it sounds like that they are put into a bucket and then mixed. It is not the case when it comes to mixing CMYK colours. It actually happens by a lot of small single-colour dots dropped onto the sheets next to each other. So when the printing is pressing it actually does not mix the colours, but it prints really small dots of cyan, magenta, yellow or key. Since the dots are so small it actually makes our eyes and brain process the dots, so it looks likes colours and the design we wanted.
When using CMYK colours to create the wished design or colour, then the CMYK colours are mixed together, and through subtractive synthesis, they create the colours that needed in the print. The subtractive synthesis is a process where the primary colours (Cyan, Magenta, Yellow, Black) are printed on the sheet as fillers. When the light hits the sheets with the colours it passes through each of the colours, and each time it passes through a colour some of the light is absorbed by the ink. The remaining light is then reflected by the white sheet and this light is what shows the colours. This means that the intensity of the colours is what decides how dark the colours are going to be. So if no colour is added to the print, it will be completely white, and if all the four colours are added at their highest intensity the print will be black. This process is in contrast to the process of RGB colours, where the less colour intensity is used the more dark the colours will be.
When making a design or a print file using CMYK colours it is important to know how the CMYK colour codes work. Luckily it is rather simple. Since we use four colours to make the design, the thing we have control is the intensity of each colour. The range of the intensity goes from 0 to 100, meaning that 100 is the highest intensity and 0 being the lowest intensity. So if you want the purest Cyan the CMYK code would be C100, M0, Y0, K0, and one on you go with the rest if you want a high intensity of the rest of the colours. The only exception is black, here the purest black would be C100, M100, Y100, K100, because the print gets darker the higher colour intensity, as explained about the subtractive synthesis.
As written at the start of this article CMYK colours are used for printing on paper and especially white paper. The CMYK colour process is the ordinary process for home-printers, but it is also used by a lot of printing companies to print flyers, posters, and for a lot of other projects. Due to the low cost of the CMYK colour process, a lot of manufacturers of printed packaging is implementing this colour process, so it is able to provide customers with lower quantities.
The CMYK colour system is not great for printing on other materials than paper, since the drops of ink have to be placed very precisely for the design to look great. Where materials such as plastic and metal are very difficult to print on and often, does the print not stick before the press is applied.