Standard black (K) vs. rich black (CMYK) values
Black is one of the most frequently used colours in printing. But, surprisingly, not all black inks are the same. Black ink can vary immensely in black and white printing and CMYK printing. You need to know that there are two main types of black: standard black and rich black.
Standard black consists of black ink (100% K) and nothing else, while rich black contains Cyan, Magenta, and Yellow. Adjusting the amount of colour means you can achieve deep, more saturated tones.
Standard black and rich black may look the same on a screen – but not in print. To ensure consistency, make sure you check your colour values. As the illustration (right) demonstrates, you can see what two different blacks will look like when printed.
When not to use rich black
Even if you have a full-colour CMYK project, always avoid rich black for small text, line art, or anything with fine details. The reason? Tiny variations in plate registration can produce blurry remnants of the four colours around the edges. This effect is called ghosting. You might have seen this effect in newspaper print.
How does ghosting appear in print?
Here is an example of ghosting (right). The thin text and black background have CMYK colour profiles (rich black) instead of greyscale (standard black). Four separate ink plates distribute ink on top of each other to create rich black. If one of these plates is slightly misaligned, you can see a ghosting effect.
