I recently asked some designers and prepress gurus what the ideal black was for printing. To quote one of the responses, “You could ask 100 different people and get 200 different answers.”
I recently asked some designers and prepress gurus what the ideal black was for printing—meaning the best combination of CMYK to achieve the richest black. I thought there might be some industry standard, some setting to rely on and then tweak from there. Instead, the answers were all over the map; to quote one of the responses, “You could ask 100 different people and get 200 different answers.”
For the non-print designers, a small course in Printing Colors 101. Most offset presses print in four colors: Cyan, Magenta, Yellow and Black, or CMYK. These colors are mixed in percentages to achieve more colors—for instance, 30% Magenta and 100% Yellow produce a nice orange. Each color can be up to 100%, so a common means of displaying a CMYK value would be 74c 17m 100y 0k (which mixed together would make a nice dark green).
However, there are some commonly accepted guidelines. First, a simple 100% mix of black is not strong enough for solid fields, or even thinner shapes, because colors underneath can bleed through. However, blocks of black body text (say it three times fast) should never be above a plain 100k, because anything higher will over saturate small serifs and punctuation.
That being said, adding more Cyan, Magenta or Yellow to the Black will drastically change the shade of the black. Adding 60% Cyan will produce a rich, cool black that is much darker than a plain 100k. A mix of 40c 30m 10y 100k will print a more neutral black, since there is now some warmer colors mixed in. The best policy is to keep the Cyan higher in the mix, as it melds well with the Black, and most people would rather see a cooler black than a warmer black. Some pressman shy away from mixing any Yellow, as it can tint the final black a slight green.
Mixing black is a case-by-case experiment: for printed pieces with a lot of blue, mixing in copious amounts of Cyan will complement the final piece; likewise, a piece with a lot of green might do well to have a nice balance of Cyan and Yellow in the black to give a slight greenish tint. While it isn’t a drastic difference, it subtly helps the overall piece.
In printing, the color mix should never be above 300%, but this depends on what kind of stock is being used. Heavy stocks can absorb more ink; lesser weight or coated stocks might be able to accept less. Many designers never mix above 250%, and colors should never be mixed higher than 230% for newsprint, or the ink will saturate and ruin the paper.
Designers should consult with their printers before mixing colors too high. On the other hand, prepress departments might want to advise designers on the limitations of their press. Communication on this matter can easily help to avoid issues before the piece goes to press.