CMYK in Print

What is CMYK?

In the print industry CMYK stands for Cyan, Magenta, Yellow and Key. Key represents Black.

You might be asking yourself why is black called key?! Supposedly the word 'key' came from the past when screw keys were used to control the flow of ink on the old presses that were used at the time. At Sticker Gizmo we just call it black!

Black (or K/KEY) is used slightly differently because it’s the main ink that influences depth and shading. The other colours are mixed together to create any colour on the spectrum and then black ink is added to adjust the overall shading.

Why do we use CMYK?

Like most commercial printers we use CMYK as its consistent and accurate. This is why we can print the same designs within the same or even different print runs keeping the colours looking exactly how they should. We can also easily monitor any changes in colour which helps keep our quality control department robust.

All modern digital printers like our Xeikon press use individual CMYK cartridges. The printer then works out how much of each colour to print in specific places which is how artwork is printed.


Its very important that all print files are set to CMYK colours and not RGB otherwise the colours you see on screen will be very different to the printed colours. RGB stands for Red, Green and Blue. Instead of ink or toner, screens blend coloured light together.

When changing an image from RGB to CMYK you will instantly notice the difference. Screens can produce extremely fluorescent shades that simply cannot be reproduced using CMYK inks and toners. Its also important to remember that CMYK colours on a screen, like your computers monitor will still differ from physical printed CMYK.

While modern technology can get it very close there’s still other variables to never forget about. This includes what brand of inks are being used, the brand of printer and even the material being printed on. The image below shows how RGB and CMYK colours react differently when mixed.

If equal amounts of 100% RGB light are mixed together then this produces white. Similar to CMYK, different values of RGB light can create any colour.

What is a True Black?

A 'true black' involves printing black ink alongside the 3 other colours. True black appears much darker than single colour black. It is required when a black part of a design sits over the top of other colours or if a design contains large areas of black.

True black is made up of 100% black while the other 3 colours can be adjusted to create what works best. The percentages we would use if a true black was required is C40%, M40%, Y40% and K100%. In the cases where a true black isn’t required, we would print 100% black on its own.

You may be asking why don’t we use 100% of all colours? The reason is because this process saves ink while giving us the best results. Remember, black is far richer than the other 3 colours so it doesn’t take a lot of the other colours to make a huge impact.

Hopefully you now understand a bit more about why CMYK is important, the basics of how it works and also the difference between CMYK and RGB colours. If you have any questions, please get in touch at [email protected]