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. You can print black and white images in colour, but grey tones may not be visible, and a colour tint may appear.
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.
Photography Rich Black vs Standard Black: What’s the Difference?
It may be tempting to see your artwork as black only when your photos are in black and white and pick the inexpensive greyscale option. But it’s always worth checking because if your black and white pictures consist of CMYK colours, your photos will lose depth.
The drawback with printing black and white photographs in CMYK is the potential to suffer unwanted colour casts. Colour casts are unintentional hues in a photo. For example, it may have a slight cyan, magenta, or yellow bias. Even if your photos appear neutral on your computer screen, the fact that all four colours make up an image when printed on a printing press, it can be challenging to appear as neutral greys, especially in digital printing.
Rich Black vs Registration Black: What’s the Difference?
Rich Black describes any black made of 4 colours. Registration black represents a black made of 100% of each C, M, Y and K, and should never be used within your artwork as the ink density is too high and will cause print issues. It is reserved for printer marks so we can check the registration.
For a high-quality Rich Black, we recommend setting your colours to C 30%, M 30%, Y 30% and K 100%. You’ll achieve a Rich Black without the ink density being too high.
