Large black areas that look greyish or blotchy in print: that is a common problem. Printing deep black is solved with a rich black: a black built up from several inks instead of black alone. That gives you a full, even black that looks luxurious.
Black is not always black
Pure black consists of 100% K (the black ink). For small text that is perfect. But on large areas pure black quickly looks dull. By laying cyan, magenta and yellow underneath it, a deeper, richer shade of black is created.
A safe rich black
- Large areas: for example C60 M40 Y40 K100 for a deep black.
- Small text: always 100% K only, to prevent blurriness.
- Do not overdo it: keep the total ink coverage below about 300% to avoid set-off.
Why it matters
Supply your file in CMYK and use rich black deliberately in the places where it counts. During our file check we also look at the total ink coverage and let you know if an area gets too much ink for the chosen paper.
When do you choose deep black printing?
A good rich black makes the difference between an amateurish and a professional look, certainly on covers, backgrounds and full-page black areas. With a photo book with dark pages or a sleekly designed cover it is almost indispensable.
For body text you do not have to think about it: that simply stays 100% K. It is purely about the large areas where depth counts. You can read more about colour build-up at the International Color Consortium.
Why you should not make your body text deep black
Deep black is meant for large areas, not for letters. As soon as text is built from four inks, those four impressions have to land exactly on top of each other. In body text of 9 or 10 point you see a deviation of a tenth of a millimetre immediately: the letters get a coloured fringe and look blurry. So always set body text in 100% black and nothing else.
For headings in a large size, logos and single words on a coloured background you can deviate. There the build-up does not show and the depth outweighs the risk. If in doubt, keep the limit at around 24 point.
Deep black printing and your choice of paper
How much ink a page can take depends on the paper. Uncoated paper absorbs ink and can tolerate less total coverage; coated paper keeps the ink on the surface and takes more. So stay below the total ink coverage that suits your paper, otherwise the ink stays wet and smears onto the next page.
Large black areas are difficult stock anyway: every fold, every finger and every scratch shows on an even dark surface. If you go for a cover that is entirely black, consider matt lamination and bear in mind that you have to handle the book more carefully. You can read more about that in our article on luxury finishes.
The paper type also determines how deep your black looks. On gloss or silk paper a rich black comes across fuller and deeper, because the ink sinks less into the paper. On uncoated (matt, rough) paper the ink sinks in slightly, which makes black seem less intense. Bear that in mind with a book with many dark areas.
Not sure how your deep black will turn out on the chosen paper? Request a proof. With a cover carrying a large black area in particular, you want to know in advance that it is even and deep, and not greyish or blotchy.
Frequently asked questions about printing deep black
What is the difference between pure black and rich black?
Pure black is 100% K (black ink only). Rich black adds cyan, magenta and yellow for a fuller, deeper result on large areas.
Which values do I use for rich black?
A safe mix is C60 M40 Y40 K100, with a total ink coverage below 300%.
Should I set text in rich black too?
No. Small text goes in 100% K, otherwise you get registration problems that make the letters blurry.