Not bling bling, but black gold…
Black is black, right? Not in print, it’s not. We’ve already covered the difference between CMYK and RGB, but even within CMYK for print, there are subtleties.
A quick point
First things first…if you’re working in RGB, stop it. We’re talking about print, and that’s done in CMYK. If you design in RGB there’s no telling how your work will look once it’s been converted by an insentient machine (that’s the printer, NOT the operator!) and output in CMYK toner or ink.
This is where everyone starts, and it’s often as far as we need to go. Pure black in print is simply 100% K. So, in a CMYK breakdown it’s 0/0/0/100. Fine, right? Probably. It’s certainly fine for text. It’s in larger areas of black that things start to unravel.
Printing works in parallel lines of dots, or screens, with the C, M, Y and K filling in the space to produce what appears to the eye as a solid area. Full-colour CMYK uses a percentage of each colour to fill in the gaps and produce a variable shade of colour. If only one of the plates is used, for example cyan, it is easier to see through the screen, as it were, to the bare paper below. Think of a fairly transparent net curtain; now think of four net curtains overlaid – it’s the same concept. The cyan, magenta and yellow plates alone don’t result in such a big problem, because there’s no reference for the brain to think, ‘wait, that’s not pure cyan…’. Black, however, we recognise intuitively. If the black looks a little faded or patchy, we’re more likely to notice.
That’s where rich black comes in.
Rich black uses colour from all four CMYK plates to produce a fuller, richer coverage on the paper. One might think that adding colour to the black would result in a muddy, brownish colour, and it can, but there are specific CMYK mixes which avoid this effect.
The primary additive to the K is usually cyan, as we’re more used to seeing a slightly blue black than anything else. In fact it’s possible to create a rich black using just 60% cyan and 100% black, but it can look a little ‘cool’. A ‘warm’ black would be something like 0-20% cyan, 60% magenta, 30% yellow and 100% black.
As with anything, the best thing is to come and see a printed example of your black mix on the intended stock, through the intended printer. If you’ve designed your work properly, with appropriate software, you should be able to adjust the swatch easily enough.
- Black: 0.0.0.100
- Rich Black: 22.214.171.124
- Cool Black: 126.96.36.199
- Warm Black: e.g. 188.8.131.52
Where and when
As stated at the beginning, pure K black is often as much as you need. The best example of this is text. Black type doesn’t require a deep, rich, full black. The fact that it’s most likely printed on a much lighter colour (probably white) will give it enough contrast that the eye will perceive it as proper black. But there’s more to it than that: if you use a rich black mix on text, you will probably end up with a coloured ghosting around the text. This is because, no matter how good the technology or how well calibrated it is, it is very difficult to exactly align the four colours C, M, Y and K. If your text is pure black, it’s not a problem, but a four-colour, rich black may show the constituent colours as feint outlines.
This still applies if you are reversing the text out in white, from a black background, although this may be unavoidable if you need to print the white text in a block of black. Usually, reversed type is used as a graphic element and will be larger, reducing the problem.
Rich black is most necessary and most effective when used in a large area of black. This is where you really need a deep, consistent coverage and avoid patchiness and see-through. Since it’s not possible to print colour or white onto black stock, printing the black is the only solution if you want a black background. Enter rich black!
It is also used in any large, solid area of black, such as display type or some sort of graphic element on the page.
- Use 100%K for text to avoid registration ghosting
- Use rich black for solid areas of black
This is a point worth addressing, because it can cause problems. Many programmes are defaulted to overprinting black when defined as 100% K. This is to prevent trapping issues with black text, etc. This may be a problem, however, if you are placing a solid area of black on top of another colour, as the black will overprint onto the other colour, which will give the black a coloured tint. You CAN fix this problem by telling the programme not to overprint black, but it may be easier to use rich black, as the programme will treat this as any other swatch and ‘knock out’ the underlying colour.
- Overprint 100%K usually the default
- Fine for text
- Turn off for blocks of black on colour, OR…
- Use rich black