Printing companies can really make your job “pop” by creating a special mix of process colors called a rich black. For newsletter printing, custom envelopes with heavy solids, even a large format print for a wall hanging, talk with your print provider about the optimal mixture of inks for a rich black.
What is a rich black?
By itself, black as a printing color for either offset or digital presswork can be functional for text but not quite as dark and opulent for large solids as its counterpart: rich black.
For CMYK (or full-color) printing, a rich black is a mixture of all or most process inks, starting with 100 percent black and then adding smaller percentages of the other colors. The exact percentages differ from printer to printer based on their preferences and experience. But it should be noted that screened percentages of the individual process colors (cyan, magenta, yellow, and black) are used to achieve this thick, dense black. The colored inks are not actually physically mixed.
When would one specify a rich black?
Let’s say you are designing a book cover with a completely black background except for the title and a photo in the center of the page. In addition to coating the page with a laminate or UV coating to make the background stand out, you might either print two “hits” of black (using two separate black ink units on press) or you might choose to specify a combination of black and other process colors as a rich black. In both cases the goal would be to lay down a thick, rich coating of ink that will be as dense as possible. The bluish and reddish hues in the other process colors can also accentuate this look.
What problems can occur with a rich black on offset equipment?
Too much ink on the page is a bad idea. It won’t dry, the press sheets will stick together or tear apart entirely, or ink will offset from one press sheet to another. Therefore, the goal is to combine enough of the cyan, magenta, yellow, and black to achieve the look of opulence without compromising the printing process. The technical term for this ideal upper limit of ink on the page is “total area coverage” or TAC. Usually this amount is about 260 percent or less (such as 100 percent black, 60 percent magenta, 35 percent cyan, and 60 percent yellow, or some other combination). Full coverage—rather than screens—of all four process colors would create a wet mess.
What problems can occur with a rich black on digital equipment?
You can also create a rich black on a digital press, combining toners in various proportions to augment the richness of the black solids. Unlike offset printing, however, by adding too high a percentage of the various colored toners, you can actually cause the pages to fuse together. Large solids on a digital press are already problematic. Increasing the total amount of toner in any one place, when combined with the high heat and pressure within the digital press, can cause multiple sheets of printing stock to stick together, jamming the equipment.
What is the optimal percentage composition of a rich black?
Wikkipedia notes 50C, 50M, 50Y, and 100K as one option for a rich black. It also includes 70C, 35M, 40Y, and 100K as a cool black (black with a bluish cast). For a warm black (a reddish black), the article suggests 35C, 60M, 60Y, and 100K. Of course these are just starting points for print providers.
It is important to use the various blacks consistently (avoid placing a warm black and a cool black side by side). To be absolutely clear on what to expect, it is also wise to print out separations before sending the job to the printer.
Whether your next design job is a print catalog, custom envelopes, a print newsletter, or even a large format print for a banner stand display, consider specifying a rich black for the solid black ink areas to make your job really “pop.” It costs a little more, but the additional ink absorbs more light, producing a much truer black.
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