The letters stand for cyan, magenta, yellow and key. Key is the black plate, which adds depth and keeps text sharp. In printing, the four colours are applied as tiny halftone dots, on top of and next to each other. From a distance, your eye blends the dots into a single mixed colour. The more ink is applied, the darker the result. Specialists call this subtractive colour mixing.
A screen works the other way round, using RGB: red, green and blue. There, colours are made from light, and the more light, the brighter the colour. Light can produce very vivid colours that printing ink on paper simply can't reach. That's why a punchy neon green or a brilliant blue often looks duller in print.
For a business, this matters as soon as your logo and colours go on paper. If you send print files in RGB, you leave the conversion to the print shop. The result can look quite different from what you saw on screen. So your corporate design should define CMYK values for every brand colour, not just HEX or RGB values. For exact shades, for example in a logo, there are also spot colours such as Pantone, which are printed as a pre-mixed ink.
What to look out for:
- Set up print files as a PDF in CMYK, using the colour profile the print shop specifies.
- Uncoated paper absorbs more ink. Colours look darker and less brilliant on it than on coated paper.
- Only a proof or a test print reliably shows how the colour will turn out, not your screen.
- Print black body text in black only, not mixed from all four colours, otherwise it quickly looks blurry.
For print jobs, we prepare the files in CMYK and check colours, bleed and fonts before they go to the print shop.
A drinks start-up from Lucerne has a bright turquoise as its brand colour, chosen on a laptop. On the first flyers, the turquoise suddenly looks greyish and flat. The reason: the file was set up in RGB and the print shop converted it automatically. For the next run, a CMYK value that comes as close as possible to the original is defined, and a proof is ordered before printing. For the labels, where the colour has to be spot on, a Pantone spot colour is used as well.